at javax.swing.ImageIcon.<init>(Unknown Source)

java 线程的应用

记得把图片加到src文件夹中确认在资源管理器能够找到所要的gif

否则会出现 报错

Exception in thread "main" java.lang.NullPointerException
 at javax.swing.ImageIcon.<init>(Unknown Source)
 at SwingAndThread.<init>(SwingAndThread.java:13)
 at SwingAndThread.main(SwingAndThread.java:49)

import java.awt.Container;
import java.net.URL;
import javax.swing.*;
public class SwingAndThread extends JFrame {
 private JLabel jl = new JLabel();
 private static Thread t;
 private int count = 0;
 private Container container = getContentPane();
 public SwingAndThread(){
  setBounds(300,200,250,100);
  container.setLayout(null);
  URL url = SwingAndThread.class.getResource("/1.jpg");
  Icon icon = new ImageIcon(url);
  jl.setIcon(icon);
  
  jl.setHorizontalAlignment(SwingConstants.LEFT);
  jl.setBounds(10,10,200,50);
  jl.setOpaque(true);
  t = new Thread(new Runnable(){
   
    public void run(){
     while(count<=200){
      jl.setBounds(count,10,200,50);
      try{
       Thread.sleep(1000);
      }catch (Exception e){
       e.printStackTrace();
      }
      count += 4;
      if(count==200){
       
       count = 10;
      }
      
     }
     
    }
   
  });
  t.start();
  container.add(jl);
  setVisible(true);
  setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
  
  
 }
 public static void main(String[] args){
  
   new SwingAndThread();
  
 }

}