I am getting Null Pointer Exception in my code in on click method.Please suggest me how can i remove it.
package co.sds.iitr.bullsandcows;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity implements OnClickListener
{
EditText Num;
Button done;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Num = (EditText) findViewById(R.id.etNum);
done = (Button) findViewById(R.id.btDone);
done.setOnClickListener(this);
}
#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 void onClick(View v)
{
// TODO Auto-generated method stub
if(v.getId()== R.id.btDone)
{
String num = Num.getText().toString();
int n = Integer.getInteger(num);
Toast.makeText(getApplicationContext(),"Your number is saved",
Toast.LENGTH_LONG).show();
Intent i = new Intent(getApplicationContext(),GuessActivtiy.class);
i.putExtra("num", n);
startActivity(i);
}
else
Toast.makeText(getApplicationContext(),"Not Found",
Toast.LENGTH_LONG).show();
}
}
GussActivity is my another activity class in which i am trying to pass my values through intent.
My log cat is looking like this.
03-02 02:01:22.080: D/gralloc_goldfish(901): Emulator without GPU emulation detected.
03-02 02:01:27.570: D/AndroidRuntime(901): Shutting down VM
03-02 02:01:27.570: W/dalvikvm(901): threadid=1: thread exiting with uncaught exception (group=0xb3aaeba8)
03-02 02:01:27.650: E/AndroidRuntime(901): FATAL EXCEPTION: main
03-02 02:01:27.650: E/AndroidRuntime(901): Process: co.sds.iitr.bullsandcows, PID: 901
03-02 02:01:27.650: E/AndroidRuntime(901): java.lang.NullPointerException
03-02 02:01:27.650: E/AndroidRuntime(901): at co.sds.iitr.bullsandcows.MainActivity.onClick(MainActivity.java:45)
03-02 02:01:27.650: E/AndroidRuntime(901): at android.view.View.performClick(View.java:4438)
03-02 02:01:27.650: E/AndroidRuntime(901): at android.view.View$PerformClick.run(View.java:18422)
03-02 02:01:27.650: E/AndroidRuntime(901): at android.os.Handler.handleCallback(Handler.java:733)
03-02 02:01:27.650: E/AndroidRuntime(901): at android.os.Handler.dispatchMessage(Handler.java:95)
03-02 02:01:27.650: E/AndroidRuntime(901): at android.os.Looper.loop(Looper.java:136)
03-02 02:01:27.650: E/AndroidRuntime(901): at android.app.ActivityThread.main(ActivityThread.java:5017)
03-02 02:01:27.650: E/AndroidRuntime(901): at java.lang.reflect.Method.invokeNative(Native Method)
03-02 02:01:27.650: E/AndroidRuntime(901): at java.lang.reflect.Method.invoke(Method.java:515)
03-02 02:01:27.650: E/AndroidRuntime(901): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
03-02 02:01:27.650: E/AndroidRuntime(901): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
03-02 02:01:27.650: E/AndroidRuntime(901): at dalvik.system.NativeStart.main(Native Method)
Please help me to resolve this.
Replace getInteger method with parseInt, to cast the String to Integer use parseInt method
As per the java doc
getInteger(String nm)
Determines the integer value of the system property with the specified name.If there is no property with the specified name, if the specified name is empty or null, or if the property does not have the correct numeric format, then null is returned.
You just try like this inside the MainActivity....
done.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent (MainActivity.this , GuessActivtiy.class);
intent.putExtra("num", n);
startActivity(intent);
}
});
Related
I am learning android programming and created a basic project using android studio.
My application crashes when I click on the getdata button.
The MainActivity.java:
package com.cs_infotech.newpathshala;
import android.app.Activity;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.content.Context;
import android.os.Build;
import android.os.Bundle;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.widget.DrawerLayout;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity
implements NavigationDrawerFragment.NavigationDrawerCallbacks {
/**
* Fragment managing the behaviors, interactions and presentation of the navigation drawer.
*/
private NavigationDrawerFragment mNavigationDrawerFragment;
/**
* Used to store the last screen title. For use in {#link #restoreActionBar()}.
*/
private CharSequence mTitle;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mNavigationDrawerFragment = (NavigationDrawerFragment)
getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();
// Set up the drawer.
mNavigationDrawerFragment.setUp(
R.id.navigation_drawer,
(DrawerLayout) findViewById(R.id.drawer_layout));
}
#Override
public void onNavigationDrawerItemSelected(int position) {
// update the main content by replacing fragments
Fragment fragment = null;
switch (position) {
case 0:
fragment = new ExampleFragment();
break;
case 1:
fragment = new Example1Fragment();
break;
case 2:
fragment = new Example2Fragment();
break;
}
if (fragment != null) {
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.container, fragment).commit();
} }
public void onSectionAttached(int number) {
switch (number) {
case 1:
mTitle = "ePathshala";
break;
case 2:
mTitle = "Daily Collection";
break;
case 3:
mTitle = "New Enrolled";
break;
}
}
public void restoreActionBar() {
ActionBar actionBar = getSupportActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setTitle(mTitle);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
if (!mNavigationDrawerFragment.isDrawerOpen()) {
// Only show items in the action bar relevant to this screen
// if the drawer is not showing. Otherwise, let the drawer
// decide what to show in the action bar.
getMenuInflater().inflate(R.menu.main, menu);
restoreActionBar();
return true;
}
return super.onCreateOptionsMenu(menu);
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((MainActivity) activity).onSectionAttached(
getArguments().getInt(ARG_SECTION_NUMBER));
}
}
}
test1.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<Button
android:id="#+id/getdata"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="23dp"
android:text="Get Data" />
<ListView
android:id="#+id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_above="#+id/getdata" />
<TextView
android:id="#+id/vers"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
<TextView
android:id="#+id/name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
<TextView
android:id="#+id/api"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>
Example1Fragment.java:
package com.cs_infotech.newpathshala;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;
import com.cs_infotech.newpathshala.R;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
public class Example1Fragment extends Fragment {
ListView list;
TextView ver;
TextView name;
TextView api;
Button btngetdata;
ArrayList<HashMap<String, String>> oslist = new ArrayList<HashMap<String, String>>();
//URL to get JSON Array
private static String url = "http://api.learn2crack.com/android/jsonos/";
//JSON Node Names
private static final String TAG_OS = "android";
private static final String TAG_VER = "ver";
private static final String TAG_NAME = "name";
private static final String TAG_API = "api";
JSONArray android = null;
private View v;
public Example1Fragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.test1, container, false);
oslist = new ArrayList<HashMap<String, String>>();
btngetdata = (Button) rootView.findViewById(R.id.getdata);
v=rootView;
btngetdata.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
new JSONParse().execute();
//Toast.makeText(getActivity(), "You Clicked at " , Toast.LENGTH_SHORT).show();
}
});
return rootView;
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
#Override
protected void onPreExecute() {
super.onPreExecute();
name = (TextView) v.findViewById(R.id.name);
ver = (TextView) v.findViewById(R.id.vers);
api = (TextView) v.findViewById(R.id.api);
pDialog = new ProgressDialog(getActivity());
pDialog.setMessage("Getting Data ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
#Override
protected JSONObject doInBackground(String... args) {
JSONParser jParser = new JSONParser();
// Getting JSON from URL
JSONObject json = jParser.getJSONFromUrl("http://api.learn2crack.com/android/jsonos/");
return json;
}
#Override
protected void onPostExecute(JSONObject json) {
pDialog.dismiss();
try {
// Getting JSON Array from URL
android = json.getJSONArray(TAG_OS);
for(int i = 0; i < android.length(); i++){
JSONObject c = android.getJSONObject(i);
// Storing JSON item in a Variable
String ver = c.getString(TAG_VER);
String name = c.getString(TAG_NAME);
String api = c.getString(TAG_API);
// Adding value HashMap key => value
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_VER, ver);
map.put(TAG_NAME, name);
map.put(TAG_API, api);
oslist.add(map);
list=(ListView) v.findViewById(R.id.list);
ListAdapter adapter = new SimpleAdapter(getActivity(), oslist,
R.layout.list_v,
new String[] { TAG_VER,TAG_NAME, TAG_API }, new int[] {
R.id.vers,R.id.name, R.id.api});
list.setAdapter(adapter);
list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Toast.makeText(getActivity(), "You Clicked at " + oslist.get(+position).get("name"), Toast.LENGTH_SHORT).show();
}
});
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
Logcat:
04-10 10:12:52.253 30126-30126/com.cs_infotech.newpathshala D/ActivityThread﹕ handleBindApplication:com.cs_infotech.newpathshala
04-10 10:12:52.343 30126-30126/com.cs_infotech.newpathshala W/ApplicationPackageManager﹕ getCSCPackageItemText()
04-10 10:12:52.343 30126-30126/com.cs_infotech.newpathshala D/DisplayManager﹕ DisplayManager()
04-10 10:12:52.423 30126-30126/com.cs_infotech.newpathshala I/dalvikvm﹕ Could not find method android.view.ViewGroup.onNestedScrollAccepted, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.onNestedScrollAccepted
04-10 10:12:52.423 30126-30126/com.cs_infotech.newpathshala W/dalvikvm﹕ VFY: unable to resolve virtual method 11359: Landroid/view/ViewGroup;.onNestedScrollAccepted (Landroid/view/View;Landroid/view/View;I)V
04-10 10:12:52.423 30126-30126/com.cs_infotech.newpathshala D/dalvikvm﹕ VFY: replacing opcode 0x6f at 0x0000
04-10 10:12:52.423 30126-30126/com.cs_infotech.newpathshala I/dalvikvm﹕ Could not find method android.view.ViewGroup.onStopNestedScroll, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.onStopNestedScroll
04-10 10:12:52.423 30126-30126/com.cs_infotech.newpathshala W/dalvikvm﹕ VFY: unable to resolve virtual method 11365: Landroid/view/ViewGroup;.onStopNestedScroll (Landroid/view/View;)V
04-10 10:12:52.423 30126-30126/com.cs_infotech.newpathshala D/dalvikvm﹕ VFY: replacing opcode 0x6f at 0x0000
04-10 10:12:52.433 30126-30126/com.cs_infotech.newpathshala I/dalvikvm﹕ Could not find method android.support.v7.internal.widget.ActionBarOverlayLayout.stopNestedScroll, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.setHideOnContentScrollEnabled
04-10 10:12:52.433 30126-30126/com.cs_infotech.newpathshala W/dalvikvm﹕ VFY: unable to resolve virtual method 9053: Landroid/support/v7/internal/widget/ActionBarOverlayLayout;.stopNestedScroll ()V
04-10 10:12:52.433 30126-30126/com.cs_infotech.newpathshala D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x000e
04-10 10:12:52.443 30126-30126/com.cs_infotech.newpathshala I/dalvikvm﹕ Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.internal.widget.TintTypedArray.getChangingConfigurations
04-10 10:12:52.443 30126-30126/com.cs_infotech.newpathshala W/dalvikvm﹕ VFY: unable to resolve virtual method 374: Landroid/content/res/TypedArray;.getChangingConfigurations ()I
04-10 10:12:52.443 30126-30126/com.cs_infotech.newpathshala D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x0002
04-10 10:12:52.443 30126-30126/com.cs_infotech.newpathshala I/dalvikvm﹕ Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.internal.widget.TintTypedArray.getType
04-10 10:12:52.443 30126-30126/com.cs_infotech.newpathshala W/dalvikvm﹕ VFY: unable to resolve virtual method 396: Landroid/content/res/TypedArray;.getType (I)I
04-10 10:12:52.443 30126-30126/com.cs_infotech.newpathshala D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x0002
04-10 10:12:52.834 30126-30126/com.cs_infotech.newpathshala D/OpenGLRenderer﹕ Enabling debug mode 0
04-10 10:12:52.934 30126-30126/com.cs_infotech.newpathshala I/Timeline﹕ Timeline: Activity_idle id: android.os.BinderProxy#41e049e0 time:9101016
04-10 10:15:04.772 30126-30126/com.cs_infotech.newpathshala I/Timeline﹕ Timeline: Activity_idle id: android.os.BinderProxy#41e049e0 time:9232856
04-10 10:15:11.359 30126-30656/com.cs_infotech.newpathshala W/dalvikvm﹕ threadid=11: thread exiting with uncaught exception (group=0x416c8bc0)
04-10 10:15:11.379 30126-30656/com.cs_infotech.newpathshala E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
Process: com.cs_infotech.newpathshala, PID: 30126
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:300)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:841)
Caused by: java.lang.SecurityException: Permission denied (missing INTERNET permission?)
at java.net.InetAddress.lookupHostByName(InetAddress.java:418)
at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
at java.net.InetAddress.getAllByName(InetAddress.java:214)
at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
at com.cs_infotech.newpathshala.JSONParser.getJSONFromUrl(JSONParser.java:44)
at com.cs_infotech.newpathshala.Example1Fragment$JSONParse.doInBackground(Example1Fragment.java:80)
at com.cs_infotech.newpathshala.Example1Fragment$JSONParse.doInBackground(Example1Fragment.java:62)
at android.os.AsyncTask$2.call(AsyncTask.java:288)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:841)
Caused by: libcore.io.GaiException: getaddrinfo failed: EAI_NODATA (No address associated with hostname)
at libcore.io.Posix.getaddrinfo(Native Method)
at libcore.io.ForwardingOs.getaddrinfo(ForwardingOs.java:61)
at java.net.InetAddress.lookupHostByName(InetAddress.java:405)
at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
at java.net.InetAddress.getAllByName(InetAddress.java:214)
at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
at com.cs_infotech.newpathshala.JSONParser.getJSONFromUrl(JSONParser.java:44)
at com.cs_infotech.newpathshala.Example1Fragment$JSONParse.doInBackground(Example1Fragment.java:80)
at com.cs_infotech.newpathshala.Example1Fragment$JSONParse.doInBackground(Example1Fragment.java:62)
at android.os.AsyncTask$2.call(AsyncTask.java:288)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:841)
Caused by: libcore.io.ErrnoException: getaddrinfo failed: EACCES (Permission denied)
at libcore.io.Posix.getaddrinfo(Native Method)
at libcore.io.ForwardingOs.getaddrinfo(ForwardingOs.java:61)
at java.net.InetAddress.lookupHostByName(InetAddress.java:405)
at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
at java.net.InetAddress.getAllByName(InetAddress.java:214)
at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
at com.cs_infotech.newpathshala.JSONParser.getJSONFromUrl(JSONParser.java:44)
at com.cs_infotech.newpathshala.Example1Fragment$JSONParse.doInBackground(Example1Fragment.java:80)
at com.cs_infotech.newpathshala.Example1Fragment$JSONParse.doInBackground(Example1Fragment.java:62)
at android.os.AsyncTask$2.call(AsyncTask.java:288)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:841)
04-10 10:15:12.330 30126-30126/com.cs_infotech.newpathshala E/OpenGLRenderer﹕ SFEffectCache:clear(), mSize = 0
04-10 10:15:12.360 30126-30126/com.cs_infotech.newpathshala E/WindowManager﹕ android.view.WindowLeaked: Activity com.cs_infotech.newpathshala.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{41e91890 V.E..... R......D 0,0-471,144} that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:388)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:248)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
at android.app.Dialog.show(Dialog.java:286)
at com.cs_infotech.newpathshala.Example1Fragment$JSONParse.onPreExecute(Example1Fragment.java:74)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:587)
at android.os.AsyncTask.execute(AsyncTask.java:535)
at com.cs_infotech.newpathshala.Example1Fragment$1.onClick(Example1Fragment.java:56)
at android.view.View.performClick(View.java:4508)
at android.view.View$PerformClick.run(View.java:18675)
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:5584)
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:1268)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)
at dalvik.system.NativeStart.main(Native Method)
04-10 10:15:14.992 30126-30656/com.cs_infotech.newpathshala I/Process﹕ Sending signal. PID: 30126 SIG: 9
How can I resolve this?
I wanted to make an app where you can make pictures and save them, but when I test it I got this error in my logcat: "java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.random/com.example.random.FotoMaker}: java.lang.NullPointerException". I think the problem has something to do with the intent, but im not sure what I need to add/change in my FotoMaker.java.
MenuScreen.java:
package com.example.random;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.widget.Button;
public class MenuScreen extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main);
findViewById(R.id.test).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Log.d("DEBUG", "test");
Intent intent = new Intent(MenuScreen.this, FotoMaker.class);
startActivityForResult(intent, 0);
}
});
findViewById(R.test1).setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Log.d("DEBUG", "test1");
Intent intent = new Intent(MenuScreen.this, FotoMaker.class);
}
});
findViewById(R.test2).setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Log.d("DEBUG", "test2");
Intent intent = new Intent(MenuScreen.this, FotoMaker.class);
}
});
findViewById(R.id.verlaat_app).setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Log.d("DEBUG", "test3");
MenuScreen.this.finish();
}
});
}
}
MenuScreen.java:
package com.example.random;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
public class FotoMaker extends Activity
{
ImageView iv;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.testpic);
iv = (ImageView) findViewById(R.id.imageView);
Button btn = (Button) findViewById(R.id.testpic);
btn.setOnClickListener(new OnClickListener()
{
#Override
public void onClick (View v){
Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(intent, 0);
}
});
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
if(requestCode == 0)
{
Bitmap theImage = (Bitmap) data.getExtras().get("data");
iv.setImageBitmap(theImage);
}
}
}
LogCat:
11-16 18:30:14.366: E/AndroidRuntime(1522): FATAL EXCEPTION: main
11-16 18:30:14.366: E/AndroidRuntime(1522): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.random/com.example.random.FotoMaker}: java.lang.NullPointerException
11-16 18:30:14.366: E/AndroidRuntime(1522): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1996)
11-16 18:30:14.366: E/AndroidRuntime(1522): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2023)
11-16 18:30:14.366: E/AndroidRuntime(1522): at android.app.ActivityThread.access$600(ActivityThread.java:127)
11-16 18:30:14.366: E/AndroidRuntime(1522): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1174)
11-16 18:30:14.366: E/AndroidRuntime(1522): at android.os.Handler.dispatchMessage(Handler.java:99)
11-16 18:30:14.366: E/AndroidRuntime(1522): at android.os.Looper.loop(Looper.java:137)
11-16 18:30:14.366: E/AndroidRuntime(1522): at android.app.ActivityThread.main(ActivityThread.java:4503)
11-16 18:30:14.366: E/AndroidRuntime(1522): at java.lang.reflect.Method.invokeNative(Native Method)
11-16 18:30:14.366: E/AndroidRuntime(1522): at java.lang.reflect.Method.invoke(Method.java:511)
11-16 18:30:14.366: E/AndroidRuntime(1522): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:809)
11-16 18:30:14.366: E/AndroidRuntime(1522): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:576)
11-16 18:30:14.366: E/AndroidRuntime(1522): at dalvik.system.NativeStart.main(Native Method)
11-16 18:30:14.366: E/AndroidRuntime(1522): Caused by: java.lang.NullPointerException
11-16 18:30:14.366: E/AndroidRuntime(1522): at com.example.random.FotoMaker.onCreate(FotoMaker.java:27)
11-16 18:30:14.366: E/AndroidRuntime(1522): at android.app.Activity.performCreate(Activity.java:4479)
11-16 18:30:14.366: E/AndroidRuntime(1522): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1050)
11-16 18:30:14.366: E/AndroidRuntime(1522): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1960)
11-16 18:30:14.366: E/AndroidRuntime(1522): ... 11 more
testpic.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ImageView
android:id="#+id/imageView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:src="#drawable/ic_launcher" />
</LinearLayout>
It seems that you forget to add testpic button id in your xml layout,Therefore in FotoMaker activity your button btn is null.
Button btn = (Button) findViewById(R.id.testpic); <-- null here
So add button view with id testpic in your testpic.xml layout file.
Button btn = (Button) findViewById(R.id.testpic);
there is no Button called testpic in the layout "testpic"
you need to add a button testpic indide your layout file , otherwise it will return null.
I am stuck trying to reading from a .txt file a name and last name into a java application, I have tryed on first method with AssetManager but my application Crash when I enter it.
The second method is with inputstream but I get 3 errors:
Description Resource Path Location Type
ByteArrayOutputStream cannot be resolved to a type MainActivity.java /MyInfo/src/com/example/myinfo line 64 Java Problem
ByteArrayOutputStream cannot be resolved to a type MainActivity.java /MyInfo/src/com/example/myinfo line 64 Java Problem
dummytext cannot be resolved or is not a field MainActivity.java /MyInfo/src/com/example/myinfo line 55 Java Problem
MainActivity.java
package com.example.myinfo;
import java.io.IOException;
import java.io.InputStream;
import android.os.Bundle;
import android.content.res.AssetManager;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/*
TextView name = (TextView) findViewById(R.id.name);
AssetManager assetManager = getAssets();
InputStream input;
try {
input = assetManager.open("info.txt");
int size = input.available();
byte[] buffer = new byte[size];
input.read(buffer);
input.close();
// byte buffer into a string
String text = new String(buffer);
nume.setText(text);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
*/
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
TextView dummytext = (TextView) findViewById(R.id.dummytext);
dummytext.setText(readText());
}
private String readText() {
InputStream inputStream = getResources().openRawResource(R.raw.dummytext);
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
int i;
try {
i = inputStream.read();
while(i!=-1){
byteArrayOutputStream.write(i);
i = inputStream.read();
}
inputStream.close();
}catch (IOException e){
e.printStackTrace();
}
return byteArrayOutputStream.toString();
}
#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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
}
and my XML is this:
<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.myinfo.MainActivity$PlaceholderFragment" >
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="87dp"
android:text="Adauga Fisier" />
<TextView
android:id="#+id/dummytext"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/nume"
android:layout_below="#+id/nume"
android:layout_marginTop="29dp"
android:text="Prenume"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="#+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_alignRight="#+id/button1"
android:layout_marginRight="14dp"
android:layout_marginTop="65dp"
android:textAppearance="?android:attr/textAppearanceLarge" />
</RelativeLayout>
I don't understand what I did wrong.
When I run the code that is now in Comments I notice that I get in Logcat NullPointerException.
LogCat:
04-07 10:06:11.298: I/dalvikvm(275): Could not find method android.content.pm.PackageManager.getActivityLogo, referenced from method android.support.v7.internal.widget.ActionBarView.<init>
04-07 10:06:11.298: W/dalvikvm(275): VFY: unable to resolve virtual method 318: Landroid/content/pm/PackageManager;.getActivityLogo (Landroid/content/ComponentName;)Landroid/graphics/drawable/Drawable;
04-07 10:06:11.298: D/dalvikvm(275): VFY: replacing opcode 0x6e at 0x008b
04-07 10:06:11.308: I/dalvikvm(275): Could not find method android.content.pm.ApplicationInfo.loadLogo, referenced from method android.support.v7.internal.widget.ActionBarView.<init>
04-07 10:06:11.308: W/dalvikvm(275): VFY: unable to resolve virtual method 314: Landroid/content/pm/ApplicationInfo;.loadLogo (Landroid/content/pm/PackageManager;)Landroid/graphics/drawable/Drawable;
04-07 10:06:11.308: D/dalvikvm(275): VFY: replacing opcode 0x6e at 0x0099
04-07 10:06:11.318: D/dalvikvm(275): VFY: dead code 0x008e-0092 in Landroid/support/v7/internal/widget/ActionBarView;.<init> (Landroid/content/Context;Landroid/util/AttributeSet;)V
04-07 10:06:11.318: D/dalvikvm(275): VFY: dead code 0x009c-00a0 in Landroid/support/v7/internal/widget/ActionBarView;.<init> (Landroid/content/Context;Landroid/util/AttributeSet;)V
04-07 10:06:11.488: D/AndroidRuntime(275): Shutting down VM
04-07 10:06:11.488: W/dalvikvm(275): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
04-07 10:06:11.498: E/AndroidRuntime(275): FATAL EXCEPTION: main
04-07 10:06:11.498: E/AndroidRuntime(275): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myinfo/com.example.myinfo.MainActivity}: java.lang.NullPointerException
04-07 10:06:11.498: E/AndroidRuntime(275): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
04-07 10:06:11.498: E/AndroidRuntime(275): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
04-07 10:06:11.498: E/AndroidRuntime(275): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
04-07 10:06:11.498: E/AndroidRuntime(275): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
04-07 10:06:11.498: E/AndroidRuntime(275): at android.os.Handler.dispatchMessage(Handler.java:99)
04-07 10:06:11.498: E/AndroidRuntime(275): at android.os.Looper.loop(Looper.java:123)
04-07 10:06:11.498: E/AndroidRuntime(275): at android.app.ActivityThread.main(ActivityThread.java:4627)
04-07 10:06:11.498: E/AndroidRuntime(275): at java.lang.reflect.Method.invokeNative(Native Method)
04-07 10:06:11.498: E/AndroidRuntime(275): at java.lang.reflect.Method.invoke(Method.java:521)
04-07 10:06:11.498: E/AndroidRuntime(275): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-07 10:06:11.498: E/AndroidRuntime(275): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-07 10:06:11.498: E/AndroidRuntime(275): at dalvik.system.NativeStart.main(Native Method)
04-07 10:06:11.498: E/AndroidRuntime(275): Caused by: java.lang.NullPointerException
04-07 10:06:11.498: E/AndroidRuntime(275): at com.example.myinfo.MainActivity.onCreate(MainActivity.java:42)
04-07 10:06:11.498: E/AndroidRuntime(275): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-07 10:06:11.498: E/AndroidRuntime(275): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
04-07 10:06:11.498: E/AndroidRuntime(275): ... 11 more
04-07 10:06:18.688: I/Process(275): Sending signal. PID: 275 SIG: 9
use this code
`InputStream input;
AssetManager assetManager = getAssets();
try {
input = assetManager.open("helloworld.txt");
int size = input.available();
byte[] buffer = new byte[size];
input.read(buffer);
input.close();
// byte buffer into a string
String text = new String(buffer);
dummytext.setText(text);
} catch (IOException e) {
e.printStackTrace();
}
`
This code open an InputStream for the file from assets manager, get size from file content, allocate byte buffer with this size and read file in this buffer, after this create new string from buffer and set this string to your textview
I found a example for switching the light on the phone here :
http://www.mkyong.com/android/how-to-turn-onoff-camera-ledflashlight-in-android/
So I snipped some code for my App and got a Error.
03-02 21:31:28.066: E/AndroidRuntime(1591): FATAL EXCEPTION: main
03-02 21:31:28.066: E/AndroidRuntime(1591): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.kaltech.led/com.kaltech.led.ActivityMAIN}: java.lang.NullPointerException
03-02 21:31:28.066: E/AndroidRuntime(1591): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
03-02 21:31:28.066: E/AndroidRuntime(1591): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
03-02 21:31:28.066: E/AndroidRuntime(1591): at android.app.ActivityThread.access$600(ActivityThread.java:130)
03-02 21:31:28.066: E/AndroidRuntime(1591): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
03-02 21:31:28.066: E/AndroidRuntime(1591): at android.os.Handler.dispatchMessage(Handler.java:99)
03-02 21:31:28.066: E/AndroidRuntime(1591): at android.os.Looper.loop(Looper.java:137)
03-02 21:31:28.066: E/AndroidRuntime(1591): at android.app.ActivityThread.main(ActivityThread.java:4745)
03-02 21:31:28.066: E/AndroidRuntime(1591): at java.lang.reflect.Method.invokeNative(Native Method)
03-02 21:31:28.066: E/AndroidRuntime(1591): at java.lang.reflect.Method.invoke(Method.java:511)
03-02 21:31:28.066: E/AndroidRuntime(1591): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
03-02 21:31:28.066: E/AndroidRuntime(1591): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-02 21:31:28.066: E/AndroidRuntime(1591): at dalvik.system.NativeStart.main(Native Method)
03-02 21:31:28.066: E/AndroidRuntime(1591): Caused by: java.lang.NullPointerException
03-02 21:31:28.066: E/AndroidRuntime(1591): at com.kaltech.led.ActivityMAIN.onCreate(ActivityMAIN.java:40)
03-02 21:31:28.066: E/AndroidRuntime(1591): at android.app.Activity.performCreate(Activity.java:5008)
03-02 21:31:28.066: E/AndroidRuntime(1591): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
03-02 21:31:28.066: E/AndroidRuntime(1591): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
03-02 21:31:28.066: E/AndroidRuntime(1591): ... 11 more
Edit :
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bat_status = (ImageView)findViewById(R.id.bat_stat);
mySwitch = (Switch) findViewById(R.id.switch_signal);
Context context = this;
PackageManager pm = context.getPackageManager();
if (!pm.hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
Log.e("err", "Device has no camera!");
return;
}
camera = Camera.open();
final Parameters p = camera.getParameters();
mySwitch.setChecked(false);
mySwitch.setOnCheckedChangeListener(new OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView,boolean isChecked) {
if(isChecked){ //EIN
bat_status.setImageResource(R.drawable.bat_signal_1);
p.setFlashMode(Parameters.FLASH_MODE_TORCH);
camera.setParameters(p);
camera.startPreview();
isLighOn = true;
}
else{ //AUS
bat_status.setImageResource(R.drawable.bat_signal_2);
p.setFlashMode(Parameters.FLASH_MODE_OFF);
camera.setParameters(p);
camera.stopPreview();
isLighOn = false;
}
}
});
}
Edit 2:
final Parameters p = camera.getParameters(); //Line 40
You're getting NullPointerException on line 40, which is:
final Parameters p = camera.getParameters();
Most likely the camera object is null. You're initializing it earlier with:
camera = Camera.open();
and Camera.open():
Creates a new Camera object to access the first back-facing camera on the device. If the device does not have a back-facing camera, this returns null.
Check if your camera is not null and proceed only then, eg.:
camera = Camera.open();
if (camera != null) {
//normal code
}
else {
//ERROR, camera is null
}
You might be getting this because:
the device does not have back-facing camera
you forgot to add
<uses-permission android:name="android.permission.CAMERA" />
in your AndroidManifest.
I am new to android application development. I was doing this tutorial app.It's a very simple one. It adds one and subtracts one from the counter.When I run it in the emulator ,it says "Unfortunately tutorial has stopped working." There are no errors in the code. The API level is 17. Please help me out.
Code for java:
public class Startingpoint extends Activity {
int counter=0;
Button add,subtract;
TextView display;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.startingpoint);
add = (Button) findViewById(R.id.bAdd);
subtract= (Button) findViewById(R.id.bSubtract);
display= (Button) findViewById(R.id.text);
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
counter++;
display.setText("The total is " + counter);
}
});
subtract.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
counter--;
display.setText("The total is " + counter);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.startingpoint, menu);
return true;
}
}
Layout code in xml :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView android:id="#+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Your total is 0"
android:textSize="35dp"
android:layout_gravity="center"
android:gravity="center"/>
<Button android:layout_width="250dp"
android:layout_height="wrap_content"
android:text="Add One"
android:layout_gravity="center"
android:textSize="25dp"
android:id="#+id/bAdd"/>
<Button android:layout_width="250dp"
android:layout_height="wrap_content"
android:text="Subtract One"
android:layout_gravity="center"
android:textSize="25dp"
android:id="#+id/bSubtract"/>
</LinearLayout>
Here is the logcat :
03-02 02:45:10.730: D/AndroidRuntime(780): Shutting down VM
03-02 02:45:10.730: W/dalvikvm(780): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
03-02 02:45:10.750: E/AndroidRuntime(780): FATAL EXCEPTION: main
03-02 02:45:10.750: E/AndroidRuntime(780): java.lang.RuntimeException: Unable to start activity ComponentInfo{tutorial.example.tutorial/tutorial.example.tutorial.Startingpoint}: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.access$600(ActivityThread.java:141)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.os.Handler.dispatchMessage(Handler.java:99)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.os.Looper.loop(Looper.java:137)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.main(ActivityThread.java:5041)
03-02 02:45:10.750: E/AndroidRuntime(780): at java.lang.reflect.Method.invokeNative(Native Method)
03-02 02:45:10.750: E/AndroidRuntime(780): at java.lang.reflect.Method.invoke(Method.java:511)
03-02 02:45:10.750: E/AndroidRuntime(780): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-02 02:45:10.750: E/AndroidRuntime(780): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-02 02:45:10.750: E/AndroidRuntime(780): at dalvik.system.NativeStart.main(Native Method)
03-02 02:45:10.750: E/AndroidRuntime(780): Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button
03-02 02:45:10.750: E/AndroidRuntime(780): at tutorial.example.tutorial.Startingpoint.onCreate(Startingpoint.java:22)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.Activity.performCreate(Activity.java:5104)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
03-02 02:45:10.750: E/AndroidRuntime(780): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
03-02 02:45:10.750: E/AndroidRuntime(780): ... 11 more
display= (Button) findViewById(R.id.text);
should be
display= (TextView) findViewById(R.id.text);
Since display is supposed to reference a TextView instance, but you're explictly casting into a Button, and these are not compatible types.
As you got the answer from A-C this time, but for next time in android application development a important suggestion:
Always see the logcat for error, and see the "Caused by:" tag, It specifies what was the cause of the problem with sufficient detail, Also see the line no that caused that error.
And try to find what can be wrong with that line of code.
For example: in your logcat it is showing-
Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.Button
at tutorial.example.tutorial.Startingpoint.onCreate(Startingpoint.java:22)
So you can try to read the log, and you will understand that in your file Startingpoint.java at line 22 which is located in onCreate method the error is android.widget.TextView cannot be cast to android.widget.Button. So you can easily remove your errors without any help.
Hope that helps not only you current problem but prevented your future time and efforts.