Drawing View in Java for Android App

draw_view.xml

 <com.maple.core_classes.DrawView
      android:layout_width="match_parent"
      android:layout_height="match_parent" />
                                  
           

DrawView.java

package com.maple.core_classes;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;


import java.util.ArrayList;
import java.util.List;

public class DrawView extends View implements View.OnTouchListener{

    Paint paint = new Paint();
    List<Point> points = new ArrayList<Point>();

    public DrawView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    public DrawView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public DrawView(Context context) {
        super(context);
        init();
    }

    private void init() {
        setFocusable(true);
        setFocusableInTouchMode(true);
        setOnTouchListener(this);
        paint.setColor(Color.BLACK);
        paint.setAntiAlias(true);
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        Point point = new Point();

        point.x = (int) event.getX();
        point.y = (int) event.getY();

        points.add(point);
        invalidate();

        return true;
    }

    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        for(Point point : points){
            canvas.drawCircle(point.x, point.y, 10, paint);
        }
    }

}