Falt form(at com.going.books.MainActivity.onCreate(MainActivity.java:19)) - java

//main activity.java
package com.going.books;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
public class MainActivity extends AppCompatActivity {
//start button
private Button startBtn;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate( savedInstanceState );
setContentView( R.layout.activity_main );
//button start
startBtn=findViewById( R.id.startBtn1 );
startBtn.setOnClickListener( new View.OnClickListener() {
#Override
public void onClick(View v) {
// Start Activity
startActivity( new Intent( MainActivity.this,Main2Activity.class ) );
}
} );
}
}
//complete
//activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/custom_uid"
android:orientation="horizontal"
android:gravity="bottom"
tools:context=".MainActivity">
<Button
android:id="#+id/startBtn1"
android:layout_width="wrap_content"
android:layout_height="80dp"
android:background="#color/white"
android:layerType="software"
android:layout_weight="1"
android:text="Start"
android:textColor="#color/Black"
android:textSize="20dp" />
<!--complete-->
</LinearLayout>'''
//logcat error
'''04-05 17:34:45.750 32139-32139/com.going.books E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.going.books, PID: 32139
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.going.books/com.going.books.MainActivity}: android.view.InflateException: Binary XML file line #2: Error inflating class
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697)
Caused by: android.view.InflateException: Binary XML file line #2: Error inflating class
at android.view.LayoutInflater.createView(LayoutInflater.java:633)
at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:55)
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:682)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:741)
at android.view.LayoutInflater.inflate(LayoutInflater.java:482)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:555)
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:161)
at com.going.books.MainActivity.onCreate(MainActivity.java:19)
at android.app.Activity.performCreate(Activity.java:6033)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697) 
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:288)
at android.view.LayoutInflater.createView(LayoutInflater.java:607)
at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:55) 
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:682) 
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:741) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:482) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:555) 
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:161) 
at com.going.books.MainActivity.onCreate(MainActivity.java:19) 
at android.app.Activity.performCreate(Activity.java:6033) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697) 
Caused by: android.content.res.Resources$NotFoundException: Resource "com.going.books:drawable/custom_uid" (7f06005f) is not a Drawable (color or path): TypedValue{t=0x1/d=0x7f06005f a=-1 r=0x7f06005f}
at android.content.res.Resources.loadDrawableForCookie(Resources.java:2441)
at android.content.res.Resources.loadDrawable(Resources.java:2381)
at android.content.res.TypedArray.getDrawable(TypedArray.java:749)
at android.view.View.(View.java:3738)
at android.view.ViewGroup.(ViewGroup.java:498)
at android.widget.LinearLayout.(LinearLayout.java:200)
at android.widget.LinearLayout.(LinearLayout.java:196)
at android.widget.LinearLayout.(LinearLayout.java:192)
at java.lang.reflect.Constructor.newInstance(Native Method) 
at java.lang.reflect.Constructor.newInstance(Constructor.java:288) 
at android.view.LayoutInflater.createView(LayoutInflater.java:607) 
at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:55) 
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:682) 
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:741) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:482) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:555) 
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:161) 
at com.going.books.MainActivity.onCreate(MainActivity.java:19) 
at android.app.Activity.performCreate(Activity.java:6033) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697) 
'''

Firstly I am not used background image so no error will appear.
then I am using a background image then the onClick() method error will be produced.
Next than not using background image so no error will be found...
but I am not sure why did hear...

Related

.setBackgroundResource(0) crashing my app

In app, I allocate resources to button in GridLayout.
if(fill[tappedButtonLocation] == 2 && !gameOver) {
fill[tappedButtonLocation] = activePlayer;
if (activePlayer == 0) {
tappedButton.setBackgroundResource(R.drawable.circle_yellow);
activePlayer = 1;
} else {
tappedButton.setBackgroundResource(R.drawable.circle_yelp);
activePlayer = 0;
}
}
Then I want to remove the resources but it crash the app.
GridLayout gridLayout = findViewById(R.id.gridLayout);
for(int i=0; i<gridLayout.getChildCount();i++){
((Button) gridLayout.getChildAt(i)).setBackgroundResource(0);
}
Allocated resource is
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="oval">
<solid android:color="#FFFC00"> </solid>
<size android:height="120dp"
android:width="120dp"> </size>
</shape>
Logcat Error:
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:390)
at android.view.View.performClick(View.java:6597)
at android.view.View.performClickInternal(View.java:6574)
at android.view.View.access$3100(View.java:778)
at android.view.View$PerformClick.run(View.java:25885)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385)
at android.view.View.performClick(View.java:6597) 
at android.view.View.performClickInternal(View.java:6574) 
at android.view.View.access$3100(View.java:778) 
at android.view.View$PerformClick.run(View.java:25885) 
at android.os.Handler.handleCallback(Handler.java:873) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:193) 
at android.app.ActivityThread.main(ActivityThread.java:6669) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
Caused by: java.lang.ClassCastException: android.support.v7.widget.GridLayout cannot be cast to android.widget.GridLayout
at com.example.tictokgame.MainActivity.playAgain(MainActivity.java:65)
at java.lang.reflect.Method.invoke(Native Method) 
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385) 
at android.view.View.performClick(View.java:6597) 
at android.view.View.performClickInternal(View.java:6574) 
at android.view.View.access$3100(View.java:778) 
at android.view.View$PerformClick.run(View.java:25885) 
at android.os.Handler.handleCallback(Handler.java:873) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:193) 
at android.app.ActivityThread.main(ActivityThread.java:6669) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
How can I remove the resource from GridView.
Actually I want to reset the tic-toc-toe game after clicking on play again button.
The problem seems to be a ClassCastException as noted in the stacktrace:
Caused by: java.lang.ClassCastException: android.support.v7.widget.GridLayout cannot be cast to android.widget.GridLayout
Please check your imports in the class, where you do the following:
GridLayout gridLayout = findViewById(R.id.gridLayout);
Change this:
import android.widget.GridLayout;
to:
import android.support.v7.widget.GridLayout;

Error after downgrade Android API from 27 to 21 (KOTLIN)

I tried to downgrade my app from api 27 to 21 because my target api is from 21 to 27. But it can only run on API 26 and 27. After downgrade i try to install on API 21 then the app cannot open (it stopped working after open)
Here is my main_activity
package com.ddm.xposed.digi_com
import android.os.Bundle
import android.support.design.widget.Snackbar
import android.support.design.widget.NavigationView
import android.support.v4.view.GravityCompat
import android.support.v7.app.ActionBarDrawerToggle
import android.support.v7.app.AppCompatActivity
import android.util.Log
import android.view.Menu
import android.view.MenuItem
import android.widget.Toast
import com.felhr.usbserial.UsbSerialDevice
import com.felhr.usbserial.UsbSerialInterface
import kotlinx.android.synthetic.main.activity_main.*
import kotlinx.android.synthetic.main.app_bar_main.*
class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelectedListener {
var unlock : Int = 0
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
setSupportActionBar(toolbar)
val toggle = ActionBarDrawerToggle(
this, drawer_layout, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close)
drawer_layout.setDrawerListener(toggle)
toggle.syncState()
nav_view.setItemIconTintList(null);
nav_view.setNavigationItemSelectedListener(this)
displayScreen(-1)
}
override fun onBackPressed() {
if (drawer_layout.isDrawerOpen(GravityCompat.START)) {
drawer_layout.closeDrawer(GravityCompat.START)
} else {
super.onBackPressed()
}
}
override fun onCreateOptionsMenu(menu: Menu): Boolean {
// Inflate the menu; this adds items to the action bar if it is present.
menuInflater.inflate(R.menu.main, menu)
return true
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
when (item.itemId) {
R.id.action_settings -> return true
else -> return super.onOptionsItemSelected(item)
}
}
fun displayScreen(id: Int){
val fragment = when(id){
R.id.nav_connect -> {
ConnectFragment()
}
else -> {
ConnectFragment()
}
}
supportFragmentManager.beginTransaction().replace(R.id.relativeLayout,fragment).commit()
}
override fun onNavigationItemSelected(item: MenuItem): Boolean {
// Handle navigation view item clicks here.
displayScreen(item.itemId)
drawer_layout.closeDrawer(GravityCompat.START)
return true
}
}
Then this is the error on debug
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.ddm.xposed.digi_com, PID: 2279
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.ddm.xposed.digi_com/com.ddm.xposed.digi_com.MainActivity}:
android.view.InflateException: Binary XML file line #16: Error
inflating class android.support.design.widget.NavigationView
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: android.view.InflateException: Binary XML file line #16: Error inflating class
android.support.design.widget.NavigationView
at android.view.LayoutInflater.createView(LayoutInflater.java:633)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:249)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:106)
at com.ddm.xposed.digi_com.MainActivity.onCreate(MainActivity.kt:32)
at android.app.Activity.performCreate(Activity.java:5937)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
at android.app.ActivityThread.access$800(ActivityThread.java:144) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5221) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:288)
at android.view.LayoutInflater.createView(LayoutInflater.java:607)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:504) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:249) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:106) 
at com.ddm.xposed.digi_com.MainActivity.onCreate(MainActivity.kt:32) 
at android.app.Activity.performCreate(Activity.java:5937) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
at android.app.ActivityThread.access$800(ActivityThread.java:144) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5221) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
Caused by: android.content.res.Resources$NotFoundException: Resource ID
0x7f060057
at android.content.res.Resources.getValue(Resources.java:1233)
at android.content.res.Resources.getDrawable(Resources.java:756)
at android.content.Context.getDrawable(Context.java:402)
at android.support.v4.content.ContextCompatApi21.getDrawable(ContextCompatApi21.java:26)
at android.support.v4.content.ContextCompat.getDrawable(ContextCompat.java:319)
at android.support.v7.internal.widget.TintManager.getDrawable(TintManager.java:145)
at android.support.v7.internal.view.menu.MenuItemImpl.getIcon(MenuItemImpl.java:422)
at android.support.design.internal.NavigationMenuPresenter$NavigationMenuAdapter.prepareMenuItems(NavigationMenuPresenter.java:393)
at android.support.design.internal.NavigationMenuPresenter$NavigationMenuAdapter.<init>(NavigationMenuPresenter.java:255)
at android.support.design.internal.NavigationMenuPresenter.getMenuView(NavigationMenuPresenter.java:97)
at android.support.design.widget.NavigationView.<init>(NavigationView.java:149)
at android.support.design.widget.NavigationView.<init>(NavigationView.java:88)
at java.lang.reflect.Constructor.newInstance(Native Method) 
at java.lang.reflect.Constructor.newInstance(Constructor.java:288) 
at android.view.LayoutInflater.createView(LayoutInflater.java:607) 
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:504) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:249) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:106) 
at com.ddm.xposed.digi_com.MainActivity.onCreate(MainActivity.kt:32) 
at android.app.Activity.performCreate(Activity.java:5937) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
at android.app.ActivityThread.access$800(ActivityThread.java:144) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5221)
Based on my answer on this SO
You are experiencing this issue because you have resources in
drawable-v26 only and you are trying to reference them in v21. Either move them to drawable folder or drawable-v21 (if these
resources are not required in lower version)
Explanation:
When you request a resource for which you provide alternatives, Android selects which alternative resource to use at runtime, depending on current device configuration.
Lets say your current OS version is 23:
OS tries selects drawables from drawable-v23 by comparing the device configuration to available alternative resources.
Based on the documentation:
The system arrives at its decision for which resources to use with the following logic:
The flowchart of how Android finds the best-matching resource is as follows
The precedence is based on the table defined here
It actually works on selection by elimination. It will first eliminate drawable-v24 and above and try to find the drawable in drawable-v23 and below. Since it cannot find the drawables in drawable-v23 and below it throws the exception

java.lang.IllegalStateException: Could not execute method for android:onClick when trying to click a button

When I click the buttons on my page, I get an "IllegalStateException" in my logcat. I'm new at Java development, so I don't really know if it's something simple that i'm doing wrong. All I'm trying to do is get the button to open the activity. It worked fine until i started playing with the fragments etc for the layout.
log cat
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.as1.app172, PID: 5621
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:5637)
at android.view.View$PerformClick.run(View.java:22429)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:5637) 
at android.view.View$PerformClick.run(View.java:22429) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6119) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.as1.app172/com.as1.app172.LoginActivity}; have you declared this activity in your AndroidManifest.xml?
at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1805)
at android.app.Instrumentation.execStartActivity(Instrumentation.java:1523)
at android.app.Activity.startActivityForResult(Activity.java:4225)
at android.support.v4.app.BaseFragmentActivityApi16.startActivityForResult(BaseFragmentActivityApi16.java:54)
at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:67)
at android.app.Activity.startActivityForResult(Activity.java:4183)
at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:720)
at android.app.Activity.startActivity(Activity.java:4522)
at android.app.Activity.startActivity(Activity.java:4490)
at com.as1.app172.Import1.BtnLogin_Click(Import1.java:25)
at java.lang.reflect.Method.invoke(Native Method) 
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
at android.view.View.performClick(View.java:5637) 
at android.view.View$PerformClick.run(View.java:22429) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6119) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
java
package com.as1.app172;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
public class Import1 extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_import1);
}
public void BtnRegister_Click (View v) {
Intent i = new Intent (Import1.this, RegistrationActivity.class);
startActivity(i);
}
public void BtnLogin_Click(View v) {
Intent i = new Intent (Import1.this, LoginActivity.class);
startActivity(i);
}
}
Check your AndroidManifest.xml and make sure you are already declared the activity LoginActivity. <activity android:name=".view.acitvity.LoginActivity" />

Binary XML file line #0: Error inflating class info.hoang8f.widget.FButton

I'm trying to create an App using Android Studio, then I face this problem, my app always stopped.
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.alfin.senior_routine, PID: 20663
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.alfin.senior_routine/com.example.alfin.senior_routine.MainActivity}: android.view.InflateException: Binary XML file line #0: Binary XML file line #0: Error inflating class info.hoang8f.widget.FButton
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: android.view.InflateException: Binary XML file line #0: Binary XML file line #0: Error inflating class info.hoang8f.widget.FButton
at android.view.LayoutInflater.inflate(LayoutInflater.java:539)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139)
at com.example.alfin.senior_routine.MainActivity.onCreate(MainActivity.java:16)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
at android.app.ActivityThread.-wrap11(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:148) 
at android.app.ActivityThread.main(ActivityThread.java:5417) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
Caused by: android.view.InflateException: Binary XML file line #0: Error inflating class info.hoang8f.widget.FButton
at android.view.LayoutInflater.createView(LayoutInflater.java:645)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:764)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:835)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:838)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:838)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:374) 
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139) 
at com.example.alfin.senior_routine.MainActivity.onCreate(MainActivity.java:16) 
at android.app.Activity.performCreate(Activity.java:6237) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
at android.app.ActivityThread.-wrap11(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:148) 
at android.app.ActivityThread.main(ActivityThread.java:5417) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance(Native Method)
at android.view.LayoutInflater.createView(LayoutInflater.java:619)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:764) 
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:835) 
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:838) 
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:838) 
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:515) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:423) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:374) 
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139) 
at com.example.alfin.senior_routine.MainActivity.onCreate(MainActivity.java:16) 
at android.app.Activity.performCreate(Activity.java:6237) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
at android.app.ActivityThread.-wrap11(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:148) 
at android.app.ActivityThread.main(ActivityThread.java:5417) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
Caused by: java.lang.UnsupportedOperationException: Can't convert to color: type=0x5
at android.content.res.TypedArray.getColor(TypedArray.java:451)
at info.hoang8f.widget.FButton.parseAttrs(FButton.java:116)
at info.hoang8f.widget.FButton.<init>(FButton.java:52)
at java.lang.reflect.Constructor.newInstance(Native Method) 
at android.view.LayoutInflater.createView(LayoutInflater.java:619) 
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:764) 
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:835) 
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:838) 
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:838) 
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:515) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:423) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:374) 
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139) 
at com.example.alfin.senior_routine.MainActivity.onCreate(MainActivity.java:16) 
at android.app.Activity.performCreate(Activity.java:6237) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
at android.app.ActivityThread.-wrap11(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:148) 
at android.app.ActivityThread.main(ActivityThread.java:5417) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
this is my code
Build.Gradle dependencies
dependencies {
compile fileTree(include: ['*.jar'], dir: 'libs')
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support',module: 'support-annotations'
})
compile 'com.android.support:appcompat-v7:26.+'
compile 'com.android.support.constraint:constraint-layout:1.0.2'
testCompile 'junit:junit:4.12'
//Add Library
compile 'com.android.support:recyclerview-v7:26.+'
compile 'com.android.support:cardview-v7:26.+'
compile 'info.hoang8f:fbutton:1.0.5'
}
Class MainActivity:
package com.example.alfin.senior_routine;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
Button btnExercises,btnSetting,btnCalendar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnExercises = (Button)findViewById(R.id.btnExercise);
btnExercises.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view){
Intent intent = new Intent(MainActivity.this,ListExercises.class);
startActivity(intent);
}
});
}
}
Class activity_main
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:fbutton="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/back"
tools:context="com.example.alfin.senior_routine.MainActivity">
<ImageView
android:id="#+id/btnTraining"
android:layout_centerInParent="true"
android:src="#drawable/play"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<LinearLayout
android:layout_alignParentBottom="true"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<LinearLayout
android:layout_weight="2"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<info.hoang8f.widget.FButton
android:id="#+id/btnExercise"
android:text="Exercises"
android:textColor="#android:color/white"
android:layout_marginLeft="8dp"
android:layout_marginRight="4dp"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
fbutton:buttonColor="#color/colorPrimary"
fbutton:shadowColor="#color/colorPrimaryDark"
fbutton:shadowEnabled="true"
fbutton:shadowHeight="2dp"
fbutton:cornerRadius="2dp"
/>
<info.hoang8f.widget.FButton
android:id="#+id/btnSetting"
android:text="Setting"
android:textColor="#android:color/white"
android:layout_marginLeft="4dp"
android:layout_marginRight="8dp"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
fbutton:buttonColor="#color/colorPrimary"
fbutton:shadowColor="#color/colorPrimaryDark"
fbutton:shadowEnabled="true"
fbutton:shadowHeight="2dp"
fbutton:cornerRadius="2dp"
/>
</LinearLayout>
<info.hoang8f.widget.FButton
android:layout_marginTop="8dp"
android:layout_marginBottom="8dp"
android:id="#+id/btnCalendar"
android:text="Calendar"
android:textColor="#android:color/white"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_width="match_parent"
android:layout_height="wrap_content"
fbutton:buttonColor="#color/colorPrimary"
fbutton:shadowColor="#color/colorPrimaryDark"
fbutton:shadowEnabled="true"
fbutton:shadowHeight="2dp"
fbutton:cornerRadius="2dp"
/>
</LinearLayout>
I already tried this tutorial, http://www.viralandroid.com/2015/12/how-to-add-library-project-to-android-studio.html and I have copy code in that link too, but the result is same, help me to solve this problem, thanks
It's a library issue, so don't waste your time suggest to change it, for more refer to this https://github.com/hoang8f/android-flat-button/issues/41
Try this
public class MainActivity extends AppCompatActivity {
//Button btnExercises,btnSetting,btnCalendar;
private FButton btnExercises;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnExercises = (FButton)findViewById(R.id.btnExercise);
btnExercises.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View view){
Intent intent = new Intent(MainActivity.this,ListExercises.class);
startActivity(intent);
}
});
}
}

Sign in Facebook

After strictly following the Facebook developer website in order to create Sign in button, I've created everything that needed. However, I was creating an project without fragment,as it's provided in documentation and it seems something went wrong. Here is my Activity
public class MainActivity extends AppCompatActivity {
CallbackManager callbackManager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.content_main);
FacebookSdk.sdkInitialize(this.getApplicationContext());
callbackManager = CallbackManager.Factory.create();
LoginButton loginButton = (LoginButton) findViewById(R.id.login_button);
loginButton.setReadPermissions("user_friends");
LoginManager.getInstance().registerCallback(callbackManager,
new FacebookCallback<LoginResult>() {
#Override
public void onSuccess(LoginResult loginResult) {
// App code
}
#Override
public void onCancel() {
// App code
}
#Override
public void onError(FacebookException exception) {
// App code
}
});
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
callbackManager.onActivityResult(requestCode, resultCode, data);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
The other part is definitely correct. I get such log:
Log:
04-18 02:12:11.348 2781-2781/com.example.vlad.sign2 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.vlad.sign2, PID: 2781
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.vlad.sign2/com.example.vlad.sign2.MainActivity}: android.view.InflateException: Binary XML file line #18: Error inflating class com.facebook.login.widget.LoginButton
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: android.view.InflateException: Binary XML file line #18: Error inflating class com.facebook.login.widget.LoginButton
at android.view.LayoutInflater.createView(LayoutInflater.java:633)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:136)
at com.example.vlad.sign2.MainActivity.onCreate(MainActivity.java:30)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:288)
at android.view.LayoutInflater.createView(LayoutInflater.java:607)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:504) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:276) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:136) 
at com.example.vlad.sign2.MainActivity.onCreate(MainActivity.java:30) 
at android.app.Activity.performCreate(Activity.java:5990) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 
Caused by: The SDK has not been initialized, make sure to call FacebookSdk.sdkInitialize() first.
at com.facebook.internal.Validate.sdkInitialized(Validate.java:145)
at com.facebook.AccessTokenTracker.<init>(AccessTokenTracker.java:55)
at com.facebook.login.widget.LoginButton$2.<init>(LoginButton.java:563)
at com.facebook.login.widget.LoginButton.configureButton(LoginButton.java:563)
at com.facebook.FacebookButtonBase.<init>(FacebookButtonBase.java:69)
at com.facebook.login.widget.LoginButton.<init>(LoginButton.java:201)
at java.lang.reflect.Constructor.newInstance(Native Method) 
at java.lang.reflect.Constructor.newInstance(Constructor.java:288) 
at android.view.LayoutInflater.createView(LayoutInflater.java:607) 
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:504) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:276) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:136) 
at com.example.vlad.sign2.MainActivity.onCreate(MainActivity.java:30) 
at android.app.Activity.performCreate(Activity.java:5990) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 
XML:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.vlad.sign2.MainActivityFragment"
tools:showIn="#layout/activity_main">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
android:id="#+id/textView" />
<com.facebook.login.widget.LoginButton
android:id="#+id/login_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_centerVertical="true"
android:layout_toRightOf="#+id/textView"
android:layout_toEndOf="#+id/textView" />
UPDATE:
After adding I get this error:
4-18 02:35:45.721 3412-3441/? E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #5
Process: com.example.vlad.sign2, PID: 3412
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.Object.hashCode()' on a null object reference
at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:746)
at java.util.concurrent.ConcurrentHashMap.containsKey(ConcurrentHashMap.java:774)
at com.facebook.internal.Utility.queryAppSettings(Utility.java:846)
at com.facebook.login.widget.LoginButton$1.run(LoginButton.java:491)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
UPDATE2:String.xml`
<resources>
<string name="app_name">Sign1</string>
<string name="action_settings">Settings</string>
<string name="facebook_app_id">277693549XXXXXX</string>
And Manifest:
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<meta-data android:name="com.facebook.sdk.ApplicationId"
android:value="#string/facebook_app_id"/>
<activity
android:name=".MainActivity"
android:label="#string/app_name"
android:theme="#style/AppTheme.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
Try this ......
It solve your problem..........
setContentView(R.layout.activity_fblogin_main);
super.onCreate(savedInstanceState);
FacebookSdk.sdkInitialize(this.getApplicationContext());
callbackManager = CallbackManager.Factory.create();
setContentView(R.layout.content_main);
All FacebookSdk initialized in OnResume() method or before setContentView(R.layout.content_main) in OnCreate method;

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