Error after pressing a button

Question

Code written for getting click event on button

public class MainActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment())
                .commit();
    }
    Button button1 = (Button) findViewById(R.id.button1);
    button1.setOnClickListener(new View.OnClickListener() {

    public void onClick(View v) 
    {
     Toast.makeText(getApplicationContext(), "Button pressed.",Toast.LENGTH_LONG).show();  
    }
    });
}

This results in can't launch error

Development Environment Eclipse with ADT

+logcat error log

08-13 16:49:46.558: E/AndroidRuntime(1143): FATAL EXCEPTION: mai 08-13 16:49:46.558: E/AndroidRuntime(1143): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test1/com.example.test1.MainActivity}: java.lang.NullPointerException 08-13 16:49:46.558: E/AndroidRuntime(1143): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651) 08-13 16:49:46.558: E/AndroidRuntime(1143): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667) 08-13 16:49:46.558: E/AndroidRuntime(1143): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 08-13 16:49:46.558: E/AndroidRuntime(1143): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935) 08-13 16:49:46.558: E/AndroidRuntime(1143): at android.os.Handler.dispatchMessage(Handler.java:99) 08-13 16:49:46.558: E/AndroidRuntime(1143): at android.os.Looper.loop(Looper.java:130) 08-13 16:49:46.558: E/AndroidRuntime(1143): at android.app.ActivityThread.main(ActivityThread.java:3687) 08-13 16:49:46.558: E/AndroidRuntime(1143): at java.lang.reflect.Method.invokeNative(Native Method) 08-13 16:49:46.558: E/AndroidRuntime(1143): at java.lang.reflect.Method.invoke(Method.java:507) 08-13 16:49:46.558: E/AndroidRuntime(1143): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847) 08-13 16:49:46.558: E/AndroidRuntime(1143): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605) 08-13 16:49:46.558: E/AndroidRuntime(1143): at dalvik.system.NativeStart.main(Native Method) 08-13 16:49:46.558: E/AndroidRuntime(1143): Caused by: java.lang.NullPointerException 08-13 16:49:46.558: E/AndroidRuntime(1143): at com.example.test1.MainActivity.onCreate(MainActivity.java:23) 08-13 16:49:46.558: E/AndroidRuntime(1143): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1050) 08-13 16:49:46.558: E/AndroidRuntime(1143): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615) 08-13 16:49:46.558: E/AndroidRuntime(1143): ... 11 more

if iv edited an xml file, it would be this.. otherwise all is generated default

    <Button
    android:id="@+id/button1"
    style="?android:attr/buttonStyleSmall"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_below="@+id/textView1"
    android:text="Button" />

Are you sure that the id "button1" exists in the XML layout ? — FR073N, Aug 13 '14 at 07:54
for sure i have the button1... well i dragged in and i didnt changed the code for now... — Hoon, Aug 13 '14 at 07:59
there must be one more xml file and one more method for fragment im MainActivity. if Yes thn please share that method too — Rohit, Aug 13 '14 at 08:01
what happens if you try `MainActivity.this` instead of `getApplicationContext()`? And which line is line 23 in your activity? — stealthjong, Aug 13 '14 at 08:10
maybe the error is for the 'if statement' in the code, if you don't write that and it generated automatically,then comment it. — mostafa88, Aug 13 '14 at 08:11
Nahh.. mainactivity.this doesnt work... and i tried deleting toast occoring code and run it, but it still did not load.... — Hoon, Aug 13 '14 at 08:15
if there is a duplicate, please have link for the location... — Hoon, Aug 13 '14 at 08:16
http://stackoverflow.com/questions/23653778/nullpointerexception-accessing-views-in-oncreate — Rohit, Aug 13 '14 at 08:17
if you dont want fragments then you can delete all things related to it and work on activities and extend your mainactivity with Activity — Rohit, Aug 13 '14 at 08:18

score 0 · Answer 1 · answered Aug 13 '14 at 07:44

0

Try this code

Button button1 = (Button) findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {

public void onClick(View v) 
{
 Toast.makeText(getApplicationContext(), "Button pressed.",Toast.LENGTH_LONG).show();  
}
});

answered Aug 13 '14 at 07:44

Elango

412
4
24

sorry.. same error... – Hoon Aug 13 '14 at 07:54
post your logcat error over here – Elango Aug 14 '14 at 05:40

Error after pressing a button

1 Answers1