How to call an Activity in Android

Question

I have the following scenario. I have 2 packages in my application. com.example.package1; org.otherexample.package2;

I declare in manifest like this:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.package1"
   android:versionCode="1"
   android:versionName="1.0" >
   <activity android:name=".ActivityfromPackage1"/>
   <activity android:name="org.otherexample.package2.ActivityFromPackage2"/>

</manifest>

This being the manifest, now I want to Call From ActivityFromPackage1 ActivityFromPackage2 I've done like this:

import org.otherexample.package2.ActivityFromPackage2
..........
Intent intent = new Intent(this,ActivityFromPackage2.class);
startActivity(intent);

I receive following error:

Unable to start Activity com.example.package1/org.otherexample.package2.ActivityFromPackage2:
JavaLang nullpointer exception

How to call the Activity? Thanks a lot.

Have you read: [launch activities from different package](http://stackoverflow.com/q/2741857/1267661)? — Sam, Nov 26 '12 at 21:41
What's in Activity2? That error is most likely coming from Activity2. It's probably expecting some values you didn't pass, or improperly coded. You should post the full stack trace with the line numbers. — garbagecollector, Nov 26 '12 at 21:41
@DumpHole nothing is in the Activity2...just a setcontentview()...the call of package is not correct... is calling firstpackage/secondpackage.Activity2...but Activity2...is just in the secondpackage...not in first.second — Dany's, Nov 26 '12 at 21:45
@Sam i read that post...but as you can saw there is written"I am assuming that by "packages" you mean applications." and my packages are in the same application.. — Dany's, Nov 26 '12 at 21:47

FoamyGuy · Accepted Answer · 2012-11-26T22:04:19.527

I suspect that something outside of what you've posted here is the root of your problem. I just made an example project to test it out.

Here are my two activity declarations in manifest:

        <activity
            android:name="com.example.packagetesting.MainActivity"
            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="com.example.anotherpackage.AnotherActivity"
            android:label="@string/title_activity_another" >
        </activity>

Here is the relavent bit from MainActivity:

import com.example.anotherpackage.AnotherActivity;
...
Intent i = new Intent(this, AnotherActivity.class);
startActivity(i);

Note that in my second Activity I had to import R from the main package:

import com.example.packagetesting.R;

But after doing that everything compiles and runs correctly.

Also note in my Log file it shows:

Starting: Intent { cmp=com.example.packagetesting/com.example.anotherpackage.AnotherActivity }

Which like yours shows both of the different package names even though AnotherActivity is only in com.example.anotherpackage

score 0 · Answer 2 · edited May 23 '17 at 11:56

0

I think that you may have to modify your manifest a little bit, try making it look more like this

   <activity android:name=".ActivityFromP2">
  <intent-filter>
    <action android:name="package2.intent.action.Launch" />
    <category android:name="android.intent.category.DEFAULT" />
  </intent-filter>
</activity>

This question is useful

launch activities from different package

edited May 23 '17 at 11:56

Community

1
1

answered Nov 26 '12 at 21:50

jcw

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score 0 · Answer 3 · answered Nov 27 '12 at 05:28

I just checked your code. It's working in my app.

Manifest:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.firstapp.tempp.testapp"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="15" />

    <uses-permission android:name="android.permission.READ_CALENDAR" />
    <uses-permission android:name="com.android.alarm.permission.SET_ALARM" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/title_activity_main" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name="org.pac.abcs.TestActivity" >
        </activity>
    </application>

</manifest>

Java Code:

btn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {

                startActivity(new Intent(MainActivity.this, TestActivity.class));
            }
        });

So its not issue of package declaration. Just one doubt, Did you import android.R in your second activity (ActivityFromPackage2) or com.example.package1.R? You will need to import com.example.package1.R.

How to call an Activity in Android

3 Answers3