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In android studio cannot resolve method 'findViewById'

I am joining two activity through intent
package com.smartcodeone.newapp1;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
public class MainActivity extends ActionBarActivity {
public static final String STRING_VAR = "com.smartcodeone.newapp1.HELLO_WORLD";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnMsg = (Button) findViewById(R.id.btnMsg);
btnMsg.setOnClickListener(new View.OnClickListener(){
//when user click's this function will be called
public void onClick(View v){
Intent intentvar = new Intent(getApplicationContext(),Main2Activity.class);
intentvar.putExtra(STRING_VAR,"Hello World"); //this is used to pass data to next intent
startActivity(intentvar);
}
});
}
private int findViewId(int btnMsg) {
return 0;
}
#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) {
// 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.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public android.support.v4.app.FragmentManager getSupportFragmentManager() {
return null;
}
}

It might have to do with Android Studio. Try cleaning your project and then rebuilding. If that doesn't work go to File -> Invalidate Caches/Restart ...
I get those issues sometimes as well. Let me know if that works. I tried your code and it works fine.

The issue seems to be that you defined a method named: findViewById(int button) that always return 0.
Use the Activity method instead of your own:
this.findViewById(int resourceId)
Good luck!

It seems you are implementing your own findviewbyid(). I don't know if you intend to do so.
Try removing
private int findviewbyid(int btnMsg) {
}
The ActionBarActivity's findviewbyid should resolve your button from your layout file.

Basic intent issue?

I am trying to build an app that displays a second activity when the button is pushed. It also changes the text of a TextView in the second activity (id:baconTextId) based on text entered in the first activity's EditText (id:ApplesInput).
Activity 1 : Apples.java
Activity 2: Bacon.java
On both buttons in the xml I put
android:onClick = "Thismethodiscalledonclick"
So that I don't need to add listeners.
I was following this tutorial on intents, but got an error. Android Studio shows no errors, but when I push the button "ApplesInput" w/ id of "ApplesInput" my phone says, "unfortunately Intent Example has stopped."
After pushing this button, I should get a screen like the following:
First activity: Apples.java
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.content.Intent;
import android.view.*;
import android.widget.*;
public class Apples extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_apples);
}
public void Thismethodiscalledonclick(View v){
Intent i = new Intent(this, Bacon.class);
final EditText ApplesInput = (EditText) findViewById(R.id.ApplesInput); //Named var and id same for simplicity
String usersmessage = ApplesInput.getText().toString(); //Whatever user types
i.putExtra("applesMessageKey", usersmessage); //Parameters == ("What do you want to call this", What piece of information?)
startActivity(i); //Starts intent stuff
}
#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_apples, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// 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.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
Second Activity: Bacon.java
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.*;
public class Bacon extends AppCompatActivity {
final TextView BaconText = (TextView) findViewById(R.id.BaconTextid);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bacon);
Bundle applesData = getIntent().getExtras(); //Call intent and store the extras in applesdata
if(applesData == null){
BaconText.setText("Must type something, sending you back...");
Thismethodiscalledonclick(null); //Take them back to first screen
return;
}
String applesDataReceived = applesData.getString("appleMessageKey");
BaconText.setText(applesDataReceived);
}
public void Thismethodiscalledonclick(View v){
Intent i = new Intent(this, Apples.class);
startActivity(i);
}
#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_bacon, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// 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.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
Some of the logcat error filtered:
android.provider.Settings$SettingNotFoundException: accessibility_enabled
at android.provider.Settings$Secure.getIntForUser(Settings.java:3163)
at android.provider.Settings$Secure.getInt(Settings.java:3148)
at com.android.systemui.power.PowerUI$1.onReceive(PowerUI.java:386)
at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:774)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5272)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:883)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
at dalvik.system.NativeStart.main(Native Method)
Feel free to ask me for anymore code or resources if you think it is needed in the problem solving process.

Try this:
private TextView BaconText;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bacon);
BaconText = (TextView) findViewById(R.id.baconText);
Bundle applesData = getIntent().getExtras(); //Call intent and store the extras in applesdata
if(applesData == null){
BaconText.setText("Must type something, sending you back...");
Thismethodiscalledonclick(null); //Take them back to first screen
return;
}
String applesDataReceived = applesData.getString("applesMessageKey");
BaconText.setText(applesDataReceived);
}
public void Thismethodiscalledonclick(View v){
Intent i = new Intent(this, MainActivity.class);
startActivity(i);
}
Call findViewById() in onCreate().
And name putExtra in ApplesActivity is "applesMessageKey" and name getString in BaconActivity is "appleMessageKey". They not same :D

Multiple buttons with different layouts

I have one activity with 5 buttons. Each button should show up one activity (total 5 different activities). I tried many methods for multiple buttons but my app does not work. The first button of the activity starts its linked activity without any problem (btEtiologia and the activity is Etiology), but the second button still won't show up, and returns to the Main Activity (that is home layout). When I restart the app, I try with the second button, and third buttons and works, but the fourth button won´t show up and returns to the main activity. I have dowloaded the app on a samsung galaxy S2 and is the same than emulator. ¿Is anything wrong with my code?
Here is the java code of Inicio:
package com.example.protesis;
import android.support.v7.app.ActionBarActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
public class Inicio extends ActionBarActivity implements View.OnClickListener {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_inicio);
Button btInformacion = (Button) findViewById(R.id.btInformacion);
btInformacion.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Toast.makeText(getBaseContext(), "Esta aplicación esta basada en el manejo de las infecciones de prótesis articulares de la IDSA", Toast.LENGTH_SHORT).show();
}
});
findViewById(R.id.btEtiologia).setOnClickListener(this);
findViewById(R.id.btAlgoritmo).setOnClickListener(this);
findViewById(R.id.btAntibioiv).setOnClickListener(this);
findViewById(R.id.btAntibioral).setOnClickListener(this);
findViewById(R.id.btRetirada).setOnClickListener(this);
}
public void onClick(View arg0){
// create a general intent
Intent intent = null;
// define an intent for all cases
switch(arg0.getId()){
case R.id.btEtiologia:
// Setting intent for first button
intent = new Intent(this,Etiology.class);
break;
case R.id.btAlgoritmo:
// Setting intent for second button
intent = new Intent(this,Algoritmo.class);
break;
case R.id.btAntibioiv:
// Setting intent for third button
intent = new Intent(this,Antibioiv.class);
break;
case R.id.btAntibioral:
// Setting intent for fourth button
intent = new Intent(this,Antibioral.class);
break;
case R.id.btRetirada:
// Setting intent for fourth button
intent = new Intent(this,Retirada.class);
break;
}
this.startActivity(intent);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.inicio, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// 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.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
The main activity code is:
package com.example.protesis;
import android.support.v7.app.ActionBarActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btInicio = (Button) findViewById(R.id.btInicio);
btInicio.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), Inicio.class);
startActivityForResult(intent, 0);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// 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.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}

As per you code, your images are dragging the code to OutOfMemory exception. Though the images which you are using of 120 dpi, their size is double to 640*480. please change image sizes then the problem will be solved. I have changed the all the 5 image sizes and now i am able to navigate to all the screens by clicking the buttons. Make the images to around 640*480 in ldpi folder.

Crashing when testing

So, I've just started views and moving between activities. I thought I got what I was looking for. I fixed all my errors, but now when I test the application it crashes. I'm new to android and eclipse. So I'm not exactly sure what's happening. Here's my MainActivity.java:
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Intent intent = getIntent();
String info = intent.getStringExtra("info_key");
TextView text = (TextView) findViewById(R.id.nametext);
text.setText(info);
}
//opens a new activity.
public void openAddItem (View v){
Intent intent = new Intent (this, Additem.class);
startActivity(intent);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
And here's my second activity; Additem.java:
package com.grocerylist;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
public class Additem extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_additem);
}
public void additem (View v){
EditText text = (EditText)findViewById(R.id.itemname);
String info = text.getText().toString();
Intent intent = new Intent(this, MainActivity.class);
intent.putExtra("info_key", info);
startActivity(intent);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_additem, menu);
return true;
}
}
Thanks, and I'm positive the problem lies where I've placed my id's.

Your first problem I see is here
Intent intent = getIntent();
String info = intent.getStringExtra("info_key");
TextView text = (TextView) findViewById(R.id.nametext);
text.setText(info);
there is no Intent to "get" if this is your first Activity. That is used when you start an Activity with an Intent and send extras. So, naturally, info is null. There will be something there when you create it from your second Activity but not when you first run your app. Also, you may want to check into using startActivityForResult in your first Activity
Second, I don't see where you call openAddItem() in your first Activity. It may be from a Button but I don't see any Buttons
It looks like you are missing some key understandings of the fundamentals of the Android framework. I suggest you start with the Docs Here if you haven't been through them already. Good luck to you
Also, this
Intent intent = new Intent (this, Additem.class);
should be this
Intent intent = new Intent (MainActivity.this, Additem.class);

the first problem I also see was already mentioned by codeMagic.
The second thing: in case you just call your methods which start another Activity in onCreate(), you will get a pseudo-infinite number of those Activities in the stack and your app will crash.
Consider watching these tutorials, it may help you to get started

Make a call-button

I am trying to add multiple buttons to my app so if you click one you automatically call a certain person, but now I'm stuck on the call-action, how can I make a call when there is being clicked on the button? I have the following code for my activity named telefoonnummers.java:
package com.example.rome;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.support.v4.app.NavUtils;
import android.widget.EditText;
import android.widget.Button;
import android.view.View;
import android.widget.Toast;
public class Telefoonnummers extends Activity {
Button mHALbellen;
Button mWITbellen;
Button mWDGbellen;
Button mVlierbellen;
Button mHotelbellen;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_telefoonnummers);
mHALbellen = (Button) findViewById(R.id.button1);
mWITbellen = (Button) findViewById(R.id.button3);
mWDGbellen = (Button) findViewById(R.id.button4);
mVlierbellen = (Button) findViewById(R.id.button5);
mHotelbellen = (Button) findViewById(R.id.button6);
// Show the Up button in the action bar.
getActionBar().setDisplayHomeAsUpEnabled(true);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_telefoonnummers, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
// This ID represents the Home or Up button. In the case of this
// activity, the Up button is shown. Use NavUtils to allow users
// to navigate up one level in the application structure. For
// more details, see the Navigation pattern on Android Design:
//
// http://developer.android.com/design/patterns/navigation.html#up-vs-back
//
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}
public void vanHalbellen(View view){
if (view == mHALbellen){
//WHICH CODE SHOULD BE HERE TO MAKE A PHONECALL WHEN THE BUTTON mHALBELLEN IS PRESSED??
}
}
}
Would you guys please help???

Add the following permission to your manifest:
<uses-permission android:name="android.permission.CALL_PHONE" />
And then execute this Intent when the button is clicked:
String uri = "tel: phone_number_here";
Intent intent = new Intent(Intent.ACTION_CALL);
intent.setData(Uri.parse(uri));
startActivity(intent);
You can also use Intent.ACTION_DIAL instead of Intent.ACTION_CALL. This shows the dialer with the number already entered, but allows the user to decide wether to actually make the call or not. ACTION_DIAL doesn't require the CALL_PHONE permission.