CODEWITHSUNDEEP
javaandroidandroid-layoutandroid-studio
Kenertj
Kenertj

Reputation: 57

Nullpointer in Android Studio

Hi so my project is having a nullpointer when starting on emulator for some reason, i am not sure what the reason is. Here is the error i am getting :

W/System.err: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setBackgroundDrawable(android.graphics.drawable.Drawable)' on a null object reference
W/System.err:     at com.panda.cleaner_batterysaver.ui.MainActivity.applyKitKatTranslucency(MainActivity.java:201)
W/System.err:     at com.panda.cleaner_batterysaver.ui.MainActivity.onCreate(MainActivity.java:83)

Code parts: 

private void applyKitKatTranslucency() {

        // KitKat translucent navigation/status bar.
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            setTranslucentStatus(true);
            SystemBarTintManager mTintManager = new SystemBarTintManager(this);
            mTintManager.setStatusBarTintEnabled(true);
            mTintManager.setNavigationBarTintEnabled(true);
            // mTintManager.setTintColor(0xF00099CC);

            mTintManager.setTintDrawable(UIElementsHelper
                    .getGeneralActionBarBackground(this));

            getActionBar().setBackgroundDrawable(
                    UIElementsHelper.getGeneralActionBarBackground(this));

        }

    }

Drawable file where the method is called :

  public class UIElementsHelper {

    private static final String NOW_PLAYING_COLOR = "NOW_PLAYING_COLOR";
    private static final String BLUE = "BLUE";
    private static final String RED = "RED";
    private static final String GREEN = "GREEN";
    private static final String ORANGE = "ORANGE";
    private static final String PURPLE = "PURPLE";
    private static final String MAGENTA = "MAGENTA";
    private static final String GRAY = "GRAY";
    private static final String WHITE = "WHITE";
    private static final String BLACK = "BLACK";

    /**
     * Returns the ActionBar color based on the selected color theme (not used
     * for the player).
     */
    public static Drawable getGeneralActionBarBackground(Context context) {
        final SharedPreferences settings = PreferenceManager
                .getDefaultSharedPreferences(context);

        Drawable drawable = new ColorDrawable(0xFF9acd32);


        return drawable;

    }

}

Upvotes: 0

Views: 74

Answers (1)

Michael Vescovo
Michael Vescovo

Reputation: 3931

In your default styles.xml file, check what theme you are using. The default theme if you create an empty Activity is:

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">

However, you may have used something like this:

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">

in which case you need to manually set the action bar like this in onCreate:

// Assuming you have a toolbar in your xml layout with id toolbar
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);

setSupportActionBar(toolbar);
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
    actionBar.setBackgroundDrawable(
                UIElementsHelper.getGeneralActionBarBackground(this));
}

If you are not using AppCompat then you will need to use getActionBar and an appropriate theme.

Upvotes: 2

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