Java 新手，想在Netbeens编写的Java程序中放图片，可是显示不出来是为什么？？？

package first;
import java.awt.*;
import javax.swing.*;

public class First extends JFrame{
  JSplitPane cf;
 // JPanel mb1,mb2;
  JList lb;
  JLabel bq;
  
  
   
   First(){
   String[] jsj={"报警显示","数据查询"};
   lb=new JList(jsj);
   bq=new JLabel(new ImageIcon("源包/first/a.jpg"));//[/code]图片显示不出来
   
   //mb1.add(bq);
   //mb2.add(lb);
   
   cf=new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,lb,bq);
   cf.setOneTouchExpandable(true);//小箭头，冲左冲右
   
   
   this.add(cf);
   
   this.setTitle("气体检测控制系统");
   this.setSize(640,480);
   this.setLocation(300,280);
   //this.setResizable(false);
   this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   this.setVisible(true);
   }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        First s1=new First();// TODO code application logic here
    }
   
}

图片路径的问题，使用绝对路径试试

package first;

import javax.swing.*;

public class First extends JFrame {
    JSplitPane cf;
    // JPanel mb1,mb2;
    JList lb;
    JLabel bq;


    First() {
        String[] jsj = {"报警显示", "数据查询"};
        lb = new JList(jsj);
        // bq = new JLabel(new ImageIcon("源包/first/a.jpg"));//

图片显示不出来
        bq = new JLabel(new ImageIcon("C:\\Windows\\System32\\oobe\\Info\\Backgrounds\\BACKGROUNDDEFAULT.jpg"));//[/code]图片显示不出来

        //mb1.add(bq);
        //mb2.add(lb);

        cf = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, lb, bq);
        cf.setOneTouchExpandable(true);//小箭头，冲左冲右


        this.add(cf);

        this.setTitle("气体检测控制系统");
        this.setSize(640, 480);
        this.setLocation(300, 280);
        //this.setResizable(false);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        First s1 = new First();// TODO code application logic here
    }

}[/code]

package first;

import javax.swing.*;

public class First extends JFrame {
    JSplitPane cf;
    // JPanel mb1,mb2;
    JList lb;
    JLabel bq;


    First() {
        String[] jsj = {"报警显示", "数据查询"};
        lb = new JList(jsj);
        // bq = new JLabel(new ImageIcon("源包/first/a.jpg"));//图片显示不出来
        bq = new JLabel(new ImageIcon("C:\\Windows\\System32\\oobe\\Info\\Backgrounds\\BACKGROUNDDEFAULT.jpg"));//

图片显示不出来

        //mb1.add(bq);
        //mb2.add(lb);

        cf = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, lb, bq);
        cf.setOneTouchExpandable(true);//小箭头，冲左冲右


        this.add(cf);

        this.setTitle("气体检测控制系统");
        this.setSize(640, 480);
        this.setLocation(300, 280);
        //this.setResizable(false);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        First s1 = new First();// TODO code application logic here
    }

}[/code]

package first;

import javax.swing.*;

public class First extends JFrame {
    JSplitPane cf;
    // JPanel mb1,mb2;
    JList lb;
    JLabel bq;


    First() {
        String[] jsj = {"报警显示", "数据查询"};
        lb = new JList(jsj);
        // bq = new JLabel(new ImageIcon("源包/first/a.jpg"));//图片显示不出来
        bq = new JLabel(new ImageIcon("C:\\Windows\\System32\\oobe\\Info\\Backgrounds\\BACKGROUNDDEFAULT.jpg"));//图片显示不出来

        //mb1.add(bq);
        //mb2.add(lb);

        cf = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, lb, bq);
        cf.setOneTouchExpandable(true);//小箭头，冲左冲右


        this.add(cf);

        this.setTitle("气体检测控制系统");
        this.setSize(640, 480);
        this.setLocation(300, 280);
        //this.setResizable(false);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        First s1 = new First();// TODO code application logic here
    }

}