button.setOnClickListener not working

Question

I have added an image and a button in the xml as follows

 <Button
        android:id="@+id/btnChangeImage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Change Image" />

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/buttonplayicon" />

onclick of the button I want to change the image. Below is the main_activity onclick function of the button

public void addListenerOnButton() {

    image = (ImageView) findViewById(R.id.imageView1);

    button = (Button) findViewById(R.id.btnChangeImage);
    button.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
        image.setImageResource(R.drawable.player_pause);

        }
    });
}

If I add

button.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
        image.setImageResource(R.drawable.player_pause);

    }
});

in the function, I get the message "Unfortunately app has stopped"

has any one idea regarding this?

EDIT 1

To view logcat if I follow ( in eclipse : Window > show view > other > android > Logcat ) steps I get Logcat(deprecated)

EDIT 2 logcat :

06-12 13:37:43.006: E/AndroidRuntime(3159): Caused by: java.lang.NullPointerException
06-12 13:37:43.006: E/AndroidRuntime(3159):     at com.example.play_audio_app.MainActivity.addListenerOnButton(MainActivity.java:38)
06-12 13:37:43.006: E/AndroidRuntime(3159):     at com.example.play_audio_app.MainActivity.onCreate(MainActivity.java:30)
06-12 13:37:43.006: E/AndroidRuntime(3159):     at android.app.Activity.performCreate(Activity.java:5231)
06-12 13:37:43.006: E/AndroidRuntime(3159):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
06-12 13:37:43.006: E/AndroidRuntime(3159):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
06-12 13:37:43.006: E/AndroidRuntime(3159):     ... 11 more
06-12 13:38:41.816: D/AndroidRuntime(3304): Shutting down VM
06-12 13:38:41.816: W/dalvikvm(3304): threadid=1: thread exiting with uncaught exception (group=0x4164eba8)
06-12 13:38:41.816: E/AndroidRuntime(3304): FATAL EXCEPTION: main
06-12 13:38:41.816: E/AndroidRuntime(3304): Process: com.example.play_audio_app, PID: 3304
06-12 13:38:41.816: E/AndroidRuntime(3304): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.play_audio_app/com.example.play_audio_app.MainActivity}: java.lang.NullPointerException
06-12 13:38:41.816: E/AndroidRuntime(3304):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at android.os.Handler.dispatchMessage(Handler.java:102)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at android.os.Looper.loop(Looper.java:136)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at android.app.ActivityThread.main(ActivityThread.java:5017)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at java.lang.reflect.Method.invokeNative(Native Method)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at java.lang.reflect.Method.invoke(Method.java:515)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at dalvik.system.NativeStart.main(Native Method)
06-12 13:38:41.816: E/AndroidRuntime(3304): Caused by: java.lang.NullPointerException
06-12 13:38:41.816: E/AndroidRuntime(3304):     at com.example.play_audio_app.MainActivity.addListenerOnButton(MainActivity.java:38)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at com.example.play_audio_app.MainActivity.onCreate(MainActivity.java:30)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at android.app.Activity.performCreate(Activity.java:5231)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
06-12 13:38:41.816: E/AndroidRuntime(3304):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
06-12 13:38:41.816: E/AndroidRuntime(3304):     ... 11 more

EDIT 3

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

        if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();
        }

        addListenerOnButton();
    }

when you've got "App has stopped" you should have a crash stacktrace print on the logcat output. post it here too ;) — Guian, Jun 12 '14 at 07:40
Is your layout properly inflated ? (findViewById would return null if its not the case.) Anyway can't guess without seeing a little bit more code and Logcat error. ( in eclipse : Window > show view > other > android > Logcat ) — Guian, Jun 12 '14 at 07:46
Depends on what is included in his java file... hard to say without seing more. — Guian, Jun 12 '14 at 08:03
you should have both Logcat and Logcat(Deprecated) but anyway open one of them, trigger the error and post the error output here plz ;) — Guian, Jun 12 '14 at 08:06
Post your activity `onCreate()` and clarify what is the name of the layout you posted — laalto, Jun 12 '14 at 08:20
http://stackoverflow.com/questions/23653778/nullpointerexception-accessing-views-in-oncreate — laalto, Jun 12 '14 at 09:29
What's this? `E/AndroidRuntime(3159): Caused by: java.lang.NullPointerException` — jyoonPro, Jun 12 '14 at 09:46

score 3 · Accepted Answer · answered Jun 12 '14 at 09:38

3

Just set onClick in the XML, it's much easier.

android:onClick="whatever"

Then in your class,

public void whatever(View v) {
    // Do your stuff
}

You do not need all this:

button.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
        image.setImageResource(R.drawable.player_pause);

        }
    });

answered Jun 12 '14 at 09:38

jyoonPro

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3

his layout is not properly inflated here so this won't help. – Guian Jun 12 '14 at 12:10

button.setOnClickListener not working

1 Answers1