CODEWITHSUNDEEP
androidandroid-layoutandroid-arrayadapter
buggydroid
buggydroid

Reputation: 1870

ArrayAdapter throws a NullPointer error

I'm trying to add a navigation drawer and I'm using the same google code sample.

But i get a null error at ArrayAdapter. 

public class HomeActivity extends AbstractBaseActivity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;

private CharSequence mDrawerTitle;
private CharSequence mTitle;
private String[] mSettiltles;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);

    mSettiltles = getResources().getStringArray(R.array.menu_items);
    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
    mDrawerList = (ListView) findViewById(R.id.left_drawer);

    // set a custom shadow that overlays the main content when the drawer opens
    //  mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
    // set up the drawer's list view with items and click listener
    mDrawerList.setAdapter(new ArrayAdapter<String>(this,
            R.layout.drawer_list_item, mSettiltles));
    mDrawerList.setOnItemClickListener(new DrawerItemClickListener());

    // enable ActionBar app icon to behave as action to toggle nav drawer
    getActionBar().setDisplayHomeAsUpEnabled(true);
    getActionBar().setHomeButtonEnabled(true);

    // ActionBarDrawerToggle ties together the the proper interactions
    // between the sliding drawer and the action bar app icon
    mDrawerToggle = new ActionBarDrawerToggle(
            this,                  /* host Activity */
            mDrawerLayout,         /* DrawerLayout object */
            R.drawable.ic_drawer,  /* nav drawer image to replace 'Up' caret */
            R.string.drawer_open,  /* "open drawer" description for accessibility */
            R.string.drawer_close  /* "close drawer" description for accessibility */
    ) {
        public void onDrawerClosed(View view) {
            getActionBar().setTitle(mTitle);
            invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        }

        public void onDrawerOpened(View drawerView) {
            getActionBar().setTitle(mDrawerTitle);
            invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        }
    };
    mDrawerLayout.setDrawerListener(mDrawerToggle);

    if (savedInstanceState == null) {
        selectItem(0);
    }
}

I've set my String array in my string values.

 <string-array name="menu_items">
    <item>My Schedule</item>
    <item>TripSummary</item>
    <item>Feedback</item>
</string-array>

Please help.

Thank you.

Logcat

12-18 06:33:41.690    1486-1486/com.myntra.delivery E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myntra.delivery/com.myntra.delivery.activities.HomeActivity}: java.lang.NullPointerException
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
        at android.app.ActivityThread.access$600(ActivityThread.java:141)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:5041)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
        at com.myntra.delivery.activities.HomeActivity.onCreate(HomeActivity.java:49)
        at android.app.Activity.performCreate(Activity.java:5104)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)

           at android.app.ActivityThread.access$600(ActivityThread.java:141)             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)             at android.os.Handler.dispatchMessage(Handler.java:99)             at android.os.Looper.loop(Looper.java:137)             at android.app.ActivityThread.main(ActivityThread.java:5041)             at java.lang.reflect.Method.invokeNative(Native Method)             at java.lang.reflect.Method.invoke(Method.java:511)              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)             at dalvik.system.NativeStart.main(Native Method)`

Upvotes: 0

Views: 500

Answers (2)

fattire
fattire

Reputation: 8843

I'm guessing it's the line:

setContentView(R.layout.activity_home);

And you probably put your ListView in another layout like DrawerLayout as implied by the tutorial. Try changing the setContentView to point to the layout where the ListView can be found.

Upvotes: 1

Ridcully
Ridcully

Reputation: 23655

I suppose line #49 is this one:

mDrawerList.setAdapter(new ArrayAdapter<String>(this,
            R.layout.drawer_list_item, mSettiltles));

Therefore, NPE can only origin from mDrawerList being null. So obviously, your layout does not contain a View with id left_drawer.

Upvotes: 1

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