Question

I am trying to write an application that starts off from a main menu (a gridview) and then creates a new activity based on the icon that is clicked by the user. Right now I am trying to simply display a blank screen for one of the icons to make sure I can successfully create a new activity. My main activity is called HomeScreen and the new activity which should be launched when I click on the first icon is called CulpaActivity. I am posting HomeScreen, CulpaActivity, and the Manifest.

public class HomeScreen extends Activity {
    /** Called when the activity is first created. */
    @Override
        public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        GridView gridview = (GridView) findViewById(R.id.gridview);
        gridview.setAdapter(new ImageAdapter(this));
        Drawable background = this.getResources().getDrawable(R.drawable.bg);
        gridview.setBackgroundDrawable(background);

    gridview.setOnItemClickListener(new OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
            Toast.makeText(HomeScreen.this, "" + position, Toast.LENGTH_SHORT).show();

            Intent cuAppIntent = null;
            switch (position){
            case 0:
                cuAppIntent.setClass(HomeScreen.this, CulpaActivity.class);
            }   
        }
    });    
    }
}

public class CulpaActivity extends Activity{
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        GridView gridview = (GridView) findViewById(R.id.gridview);
        gridview.setAdapter(new ImageAdapter(this));
        gridview.setBackgroundDrawable(null);
    }
}

And here is the Manifest:

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

<supports-screens
    android:anyDensity="true"
    android:largeScreens="true"
    android:normalScreens="true"
    android:resizeable="true"
    android:smallScreens="true" />

<application
    android:debuggable="true"
    android:icon="@drawable/icon"
    android:label="@string/app_name" >
    <activity
        android:label="@string/app_name"
        android:name=".HomeScreen" >
        <intent-filter >
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".CulpaActivity" >
    </activity>
</application>

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

<uses-permission android:name="android.permission.READ_CONTACTS" />
<uses-permission android:name="android.permission.INTERNET" />
</manifest>

Answer 1

I think this is your problem:

Intent cuAppIntent = null;

You define cuAppIntent as null yet you directly access cuAppIntent.setClass() without initializing cuAppIntent first.

switch (position){
    case 0:
        cuAppIntent.setClass(HomeScreen.this, CulpaActivity.class);
} 

To fix it, try to initialize first:

Intent cuAppIntent = new Intent();

and then add:

startActivity(cuAppIntent);

right after calling cuAppIntent.setClass()