根据点画线java

package com.yang;

import java.awt.Color;
import java.awt.Graphics;
import java.util.ArrayList;
import java.util.List;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class drawlineforspline extends JFrame{
    
    private static final long serialVersionUID = 1L;
    static List <mypoint>plist;
    public static class mypoint{
        int x;
        int y;
        public mypoint(int x,int y){
            this.x=x;
            this.y=y;
        }
    }
    public drawlineforspline(){
        init();
    }
    public drawlineforspline(ArrayList plist){
        init();
        this.plist=plist;
         
    }
    private void init(){
     
        this.setTitle("drawline");
        this.setBounds(200, 200, 500, 400);
        this.setBackground(Color.white);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setLocationRelativeTo(null);
        this.setVisible(true); 
        
        plist =new ArrayList();
        plist.add(new mypoint(50,80));
        plist.add(new mypoint(50,120));
        plist.add(new mypoint(80,50));
        plist.add(new mypoint(150,10));
        plist.add(new mypoint(180,80));
        plist.add(new mypoint(230,200));
        
    }
 
    
    public class Mypanel extends JPanel{     
        public void paint(Graphics g){
            mypoint fromP=new mypoint(50,80);
            mypoint toP=new mypoint(370,240);
            for(int i=0;i<plist.size()-1;i++){
                g.drawLine(plist.get(i).x, plist.get(i).y, plist.get(i+1).x, plist.get(i+1).y);
            }
        }
    }
    
    public static void main(String[] args) {
        drawlineforspline d=new drawlineforspline();
        Mypanel myp=d.new Mypanel();
        d.add(myp);
    }

}