canvas.drawPoint不起作用

Paint paint3 = new Paint();
paint3.setAntiAlias(true);
paint3.setColor(Color.BLACK);
paint3.setStrokeWidth(20);
paint3.setStrokeCap(Paint.Cap.ROUND);
canvas.drawPoint(centerX, centerY, paint3);

        canvas.drawCircle() 和 canvas.drawRect()都是可以的，canvas.drawPoint()就不起作用了，why？