Null pointer exception while starting one activity from another

Question

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:
                   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);
}

"`07-18 12:32:29.516: ERROR/AndroidRuntime(601): at om.firstapp.MyPackage.ActivityTwo.(ActivityTwo.java:23)`" It looks like a problem with the field declaration (the "global" scope of your ActivityTwo class) in you're ActivityTwo. Can you post those? — Ribose, Jul 18 '11 at 07:53
I agree with @Ribose. I would also like to request your constructor for `ActivityTwo` (if any). — dbm, Jul 18 '11 at 09:01
I dont have any constructor for the ActivityTwo class.. Although if reqd. the class structure is as follows: `public class ActivityTwo extends ListActivity { public ListView listView = getListView(); @Override public void onCreate(Bundle savedInstanceState) { // Posted above } //Other functions follow }` — Ojas, Jul 18 '11 at 09:06

score 1 · Answer 1 · edited May 23 '17 at 10:34

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?

Sorry for the typo ...The intent line is : Intent editIntent = new Intent(getApplicationContext(), ActivityTwo.class); — Ojas, Jul 18 '11 at 08:56
Can you suggest me with any alternate way of starting this activity if it is known to cause problems ?? — Ojas, Jul 18 '11 at 09:08
From the given stack trace I think something in your constructor for `ActivityTwo` is fishy. Or if there is no constructor then some field definitions might cause the issue. Perhaps some `public static final...` definition gone berserk. Could you perhaps edit your question above, including the constructor (if any) and your class-global variable definitions? — dbm, Jul 18 '11 at 09:13
Ah... sorry, I just noticed you've already posted notes accordingly on your question. — dbm, Jul 18 '11 at 09:14

score 0 · Answer 2 · answered Aug 27 '13 at 09:13

0

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

answered Aug 27 '13 at 09:13

user1999099

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sravan · Answer 3 · 2011-07-18T11:54:36.373

0

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

edited Jul 18 '11 at 11:54

answered Jul 18 '11 at 08:40

sravan

5,303
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Null pointer exception while starting one activity from another

3 Answers3