Null pointer exception while starting one activity from another

I am trying to start one activity from another on user selection from a context menu. The code for code context menu case is:

case R.id.organize:
                   开发者_StackOverflow社区Log.d(LOGTAG, "Creating intent");
            Intent editIntent = new Intent(getApplicationContext(), AddToList.class);
            editIntent.putParcelableArrayListExtra("userPackageList", userPackages);
            Log.d(LOGTAG, "Starting activity");
            startActivity(editIntent);
            return true; 

And my AndroidManifest.xml also has entries for both the activities:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.firstapp.MyPackage"
      android:versionCode="1"
      android:versionName="1.0">


    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".ActivityOne"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".ActivityTwo"
                  android:label="@string/app_name">
        </activity>
    </application>
</manifest>

The output prints both the log statements in the switch case and then crashes with the following exception:

07-18 12:32:29.516: ERROR/AndroidRuntime(601): FATAL EXCEPTION: main
07-18 12:32:29.516: ERROR/AndroidRuntime(601): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.firstapp.MyPackage/com.firstapp.MyPackage.ActivityTwo}: java.lang.NullPointerException
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.os.Looper.loop(Looper.java:123)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.app.ActivityThread.main(ActivityThread.java:4627)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at java.lang.reflect.Method.invokeNative(Native Method)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at java.lang.reflect.Method.invoke(Method.java:521)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at dalvik.system.NativeStart.main(Native Method)
07-18 12:32:29.516: ERROR/AndroidRuntime(601): Caused by: java.lang.NullPointerException
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.app.Activity.setContentView(Activity.java:1647)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.app.ListActivity.ensureList(ListActivity.java:314)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.app.ListActivity.getListView(ListActivity.java:299)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at com.firstapp.MyPackage.ActivityTwo.<init>(ActivityTwo.java:23)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at java.lang.Class.newInstanceImpl(Native Method)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at java.lang.Class.newInstance(Class.java:1429)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
07-18 12:32:29.516: ERROR/AndroidRuntime(601):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577)

The oncreate() method for the ActivityTwo is below:

@Override
public void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    ArrayList<PackageInfo> installedPkg = new ArrayList<PackageInfo>();
    installedPkg = getIntent().getParcelableArrayListExtra ("userPackageList"); 
    addItemsToList(installedPkg);
    setContentView(R.layout.main);
}

EDIT:

According to your notes your ActivityTwo looks something like this:

public class ActivityTwo extends ListActivity {
    public ListView listView = getListView();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ArrayList<PackageInfo> installedPkg = new ArrayList<PackageInfo>();
        installedPkg = getIntent().getParcelableArrayListExtra ("userPackageList"); 
        addItemsToList(installedPkg);
        setContentView(R.layout.main);
    }

    //Other functions follow
}

I think the exception is caused by the public ListView listView = getListView(); line. Maybe you could try to rewrite your code to something like this:

public class ActivityTwo extends ListActivity {
    public ListView listView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        listView = getListView();
    }

    @Override
    public void onResume() {
        ArrayList<PackageInfo> installedPkg = new ArrayList<PackageInfo>();
        installedPkg = getIntent().getParcelableArrayListExtra ("userPackageList"); 
        addItemsToList(installedPkg);
    }

    //Other functions follow
}

ORIGIN:

Maybe I'm stupid or something but in your code example you're defining your edit intent as:

Intent editIntent = new Intent(getApplicationContext(), AddToList.class);

But I don't see any AddToList activity-definition in your manifest.xml (you have ActivityOne and ActivityTwo)

Also there are situations where one should be careful with getApplicationContext(). Using Application context everywhere?

hello in your manifest file add your Activity name Correctly thid tag name for communication.

Here Suppose your Activity name is AddToList.java

activity android:name=".AddToList" android:label="@string/app_name"

but in your menfest ur activity name you written : ActivityTwo so try tag in manifest file

Just check the R.id values u r using. All the values you use must be present in the layout that you set in the setContentview