Starting Cascading Activities on Button Click

Question

I have various activites in my android application lets say Activity1,Activity2,Activity3 etc

All are started by intent object on button Click or list view selection event.On Some activites like in Activity1 i store a bundle inside an intent object and then start an Activity2, On the Second Activity the startActivity() method doesnot work is it memory related issue like intent too heavy to go to next Activity3.

Following is my code

Class Activity2 extends Activity
{
     private Intent i;
     private Button btn;
     @Override 
      protected void onCreate(Bundle b)
      {
            //super...
            i=new Intent(Activity2.this,Activity3.class);
            //btn=.....

//following is button click event from which i will navigate to Activity3

btn.setOnClickListener(new OnClickListener() 
        {    

    @Override
    public void onClick(View arg0) {
        // TODO Auto-generated method stub
        startActivity(i); //here it crashed
    }});

}

Is it memory related issue or coding problem? if coding problem then how else Activity can be started other than intent.

Following is Log

02-05 02:55:53.367: E/AndroidRuntime(4500): FATAL EXCEPTION: main
02-05 02:55:53.367: E/AndroidRuntime(4500): java.lang.RuntimeException: Unable to pause activity {com.example.viva_project/com.example.viva_project.MainActivity}: java.lang.NullPointerException
02-05 02:55:53.367: E/AndroidRuntime(4500):     at android.app.ActivityThread.performPauseActivity(ActivityThread.java:2358)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at android.app.ActivityThread.performPauseActivity(ActivityThread.java:2315)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:2295)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at android.app.ActivityThread.access$1700(ActivityThread.java:117)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:942)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at android.os.Handler.dispatchMessage(Handler.java:99)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at android.os.Looper.loop(Looper.java:130)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at android.app.ActivityThread.main(ActivityThread.java:3687)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at java.lang.reflect.Method.invokeNative(Native Method)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at java.lang.reflect.Method.invoke(Method.java:507)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at dalvik.system.NativeStart.main(Native Method)
02-05 02:55:53.367: E/AndroidRuntime(4500): Caused by: java.lang.NullPointerException
02-05 02:55:53.367: E/AndroidRuntime(4500):     at com.example.viva_project.MainActivity.onPause(MainActivity.java:309)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at android.app.Activity.performPause(Activity.java:3851)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at android.app.Instrumentation.callActivityOnPause(Instrumentation.java:1191)
02-05 02:55:53.367: E/AndroidRuntime(4500):     at android.app.ActivityThread.performPauseActivity(ActivityThread.java:2345)
02-05 02:55:53.367: E/AndroidRuntime(4500):     ... 12 more



protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    connectThread.killConnectThread();
     }

Answer 1

您必须在清单中提及所有3个活动。

Answer 2

Caused by: java.lang.NullPointerException at com.example.viva_project.MainActivity.onPause(MainActivity.java:309)

the problem is here:

connectThread.killConnectThread();

connectThread is null and you are tryin to execute the method killConnectThread() !

Be sure to have Activity1, Activity2, and Activity3 registered into your Manifest.xml