Question

Android tells me that The application has stopped unexcepetedly, but there are no error’s in my code.

package com.example.helloandroid;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.TableLayout;

public class HelloAndroid extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        for(int i = 0; i < 6; i++) {
            TableLayout tl = (TableLayout) findViewById(R.id.T);
            for(int j = 0; j < 6; j++) {
                ImageView img = (ImageView) tl.getChildAt(j);
                img.setImageResource(R.drawable.w);
            }
        }
    }
}

Logcat says:

03-03 19:25:43.550: WARN/dalvikvm(487): threadid=1: thread exiting with uncaught exception (group=0x40015560)
03-03 19:25:43.580: ERROR/AndroidRuntime(487): FATAL EXCEPTION: main
03-03 19:25:43.580: ERROR/AndroidRuntime(487): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.helloandroid/com.example.helloandroid.HelloAndroid}: java.lang.ClassCastException: android.widget.TableRow
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at android.os.Looper.loop(Looper.java:123)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at android.app.ActivityThread.main(ActivityThread.java:3683)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at java.lang.reflect.Method.invokeNative(Native Method)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at java.lang.reflect.Method.invoke(Method.java:507)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at dalvik.system.NativeStart.main(Native Method)
03-03 19:25:43.580: ERROR/AndroidRuntime(487): Caused by: java.lang.ClassCastException: android.widget.TableRow
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at com.example.helloandroid.HelloAndroid.onCreate(HelloAndroid.java:17)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
03-03 19:25:43.580: ERROR/AndroidRuntime(487):     ... 11 more

EDIT: The problem was on the layout:

package com.example.helloandroid;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.TableLayout;
import android.widget.TableRow;

public class HelloAndroid extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        for(int i = 0; i < 7; i++) {
            TableLayout tl = (TableLayout) findViewById(R.id.T);
            TableRow tr = (TableRow) tl.getChildAt(i);
            for(int j = 0; j < 7; j++) {
                ImageView img = (ImageView) tr.getChildAt(j);
                img.setImageResource(R.drawable.w);
            }
        }
    }
}

Answer 1

Look at Logcat to see the stack trace which will pinpoint the fault location.

My guess is that findViewById() or getChildAt() is returning null, i.e. your layout isn’t quite what you think it is.