public class DonutView extends View {

    Context context;
    int value = 0;
    int size;
    int strokeSize;
    int textSize;

    int width;
    int height;


    public DonutView(Context context) {
        super(context);
        this.context = context;
        init();
    }

    public DonutView(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        init();
    }

    public DonutView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        this.context = context;
        init();
    }

    private void init() {
        size = getResources().getDimensionPixelSize(R.dimen.donut_size);
        strokeSize = getResources().getDimensionPixelSize(R.dimen.donut_stroke_size);
        textSize = getResources().getDimensionPixelSize(R.dimen.donut_text_size);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        width = MeasureSpec.getSize(widthMeasureSpec);
        height = MeasureSpec.getSize(heightMeasureSpec);
    }

    public void setValue(int value) {
        this.value = value;
        invalidate();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawColor(Color.alpha(Color.CYAN)); // clear all

        RectF rectF = new RectF(20, 20, size - 20, size - 20);

        Paint paint = new Paint();
        paint.setColor(Color.LTGRAY);
        paint.setAntiAlias(true);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(strokeSize);

        canvas.drawArc(rectF, 0, 360, false, paint);

        paint.setColor(Color.RED);
        paint.setStrokeJoin(Paint.Join.ROUND);
        canvas.drawArc(rectF, -90, value, false, paint);

        paint.setTextSize(textSize);
        paint.setStrokeWidth(5);
        paint.setColor(Color.RED);
        String txt = String.valueOf(value);
        int xPos = width / 2 - (int)(paint.measureText(txt) / 2);
        int yPos = (int)(height / 2 - ((paint.descent() + paint.ascent()) / 2));
        canvas.drawText(txt, xPos, yPos, paint);
    }
}