How to Generate Gradient Color through Programatically in Android?

final LinearLayout layout = (LinearLayout) findViewById(R.id.main);

        try {

            int coloura = 4621323;

            int colourb = 1129730;

            int colora[] = new int[4];

            int colorb[] = new int[4];

            colora[0] = (int) ((coloura) >> 16);

            colora[1] = (int) ((coloura) >> 8);

            colora[2] = (int) coloura ;

            colora[3] = 255;

            colorb[0] = (int) ((colourb) >> 16);

            colorb[1] = (int) ((colourb) >> 8);

            colorb[2] = (int) (colourb);

            colorb[3] = 255;

            int a = Color.argb(colora[3], colora[0], colora[1], colora[2]);

            int b = Color.argb(colorb[3], colorb[0], colorb[1], colorb[2]);

            final GradientDrawable gd = new GradientDrawable(

                    GradientDrawable.Orientation.TOP_BOTTOM,

                    new int[] {a, b});

            gd.setGradientCenter(0.f, 1.f);

            gd.setLevel(2);

            layout.setBackgroundDrawable(gd);

        } catch (Exception e) {

            e.printStackTrace();

        }

Color.argb(colora[3], colora[0], colora[1], colora[2]); -->> Alpha (0 to 255), Red, Green and Blue