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);
}

}