求教：java编程出错了，求解

import java.awt.* ;
import javax.swing.* ;
public class liushibuju {
    JButton[] an = {null,null,null,null,null,null,null,null};

    public static void main(String[] args){
        lsbj ls = new lsbj();
    }
   
    class lsbj{
        an[0] = new JButton("话梅1");
        an[1] = new JButton("话梅2");
        an[2] = new JButton("话梅3");
        an[3] = new JButton("话梅4");
        an[4] = new JButton("话梅5");
        an[5] = new JButton("话梅6");
        an[6] = new JButton("话梅7");
        an[7] = new JButton("话梅8");
        this.setLayout(new FlowLayout());//这里申明FlowLayout,是因为系统默认为BoderLayout
        this.add(an[0]);
        this.add(an[1]);
        this.add(an[2]);
        this.add(an[3]);
        this.add(an[4]);
        this.add(an[5]);
        this.add(an[6]);
        this.add(an[7]);
        this.setTitle("流式布局FlowLayout");
        this.setSize(380,120);
        this.setLocation(200,200);
        this.setRestizable(false);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);
    }
}