Attempt to invoke virtual method in Resources res = getResources();

Question

I am trying to change the background color of an activity using a handler, but I am getting an error \"Attempt to invoke virtual method\".

Here is my code

Answer 1

Why do you need res and clrItems as fields? However you can do something like this

public class MainActivity extends AppCompatActivity {

private EditText editTextUser, editTextPass;
private RelativeLayout relativeLayoutMain;
private Random random = new Random();
Intent intent;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    relativeLayoutMain = (RelativeLayout) findViewById(R.id.relativeLayoutMain);

    res = getResources();
    clrItems = res.getIntArray(R.array.color_background);

    Button btnSignIn = (Button) findViewById(R.id.buttonSignIn);
    btnSignIn.setEnabled(false);

    handler.postDelayed(runner, 2000);

    Button buttonSignUp = (Button) findViewById(R.id.buttonSignUp);
    buttonSignUp.setText("Not registered? CLICK HERE");

    editTextUser = (EditText) findViewById(R.id.editTextUser);
    editTextPass = (EditText) findViewById(R.id.editTextPassword);


    if (editTextUser.getText().toString() != null && editTextPass.getText().toString() != null) {
        btnSignIn.setEnabled(true);
    }


}

android.content.res.Resources res;
int[] clrItems;

List arrayOfColor = new ArrayList();

public List getArrayOfColor() {
    arrayOfColor.add(clrItems);
    return arrayOfColor;
}

Runnable runner = new Runnable() {
    @Override
    public void run() {
        Log.e("run: ", "call");

        Bitmap bitmap = Bitmap.createBitmap(612, 612, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);

        final int clr = 0xFF424242;
        final Paint paint = new Paint();
        final Rect destRect = new Rect((612-bitmap.getWidth())/2,
                24,
                (612)-(612-bitmap.getWidth())/2,
                612-24);
        final RectF rectF = new RectF(destRect);
        final Rect srcRect = new Rect(0, 0, bitmap.getWidth(), 612);
        final float roundPx = 612;

        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(clr);
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);

        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        canvas.drawBitmap(bitmap, srcRect, destRect, paint);

        GradientDrawable gd = new GradientDrawable(GradientDrawable.Orientation.LEFT_RIGHT, new int[]{0xFF616261, 0xFF131313});
        gd.setCornerRadius(0f);
        relativeLayoutMain.setBackground(gd);
        handler.postDelayed(runner, 4000);
    }
};

public void login(View view) {
    intent = new Intent(this, HomeActivity.class);
    startActivity(intent);
}

public void register(View view) {
    intent = new Intent(this, SignUpActivity.class);
    startActivity(intent);
}
}