JAVA计算机不显示

package ai1;
import javax.swing.;
import java.awt.;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class Ts {
public static void main(String[] args) {
JS win=new JS();
}
}
class JS extends JFrame implements ActionListener{
private StringBuilder sBuilder = new StringBuilder();
JTextArea text=new JTextArea();
double a,b;
Double sum;
int i;
public JS()
{
setBounds(100,100,400,400);
setTitle("计算器");
JMenuBar menubar=new JMenuBar();
this.setLayout(new BorderLayout());
JPanel p1=new JPanel();
JPanel p2=new JPanel();
text.setPreferredSize(new Dimension (370,60));//设置组件大小
p2.setLayout(new FlowLayout());
p1.add(text);
this.add(p1,BorderLayout.NORTH);

    p2.setLayout(new GridLayout(5,4));    //添加按钮
    JButton button[]=new JButton[20];
    button[0]=new JButton("C");    
    button[1]=new JButton("CE");
    button[2]=new JButton("%");    
    button[3]=new JButton("÷");
    button[4]=new JButton("7");
    button[5]=new JButton("8");
    button[6]=new JButton("9");
    button[7]=new JButton("x"); 
    button[8]=new JButton("4");
    button[9]=new JButton("5");
    button[10]=new JButton("6");
    button[11]=new JButton("—");
    button[12]=new JButton("1");
    button[13]=new JButton("2");
    button[14]=new JButton("3");
    button[15]=new JButton("+");
    button[16]=new JButton("±");    
    button[17]=new JButton("0");
    button[18]=new JButton("."); 
    button[19]=new JButton("="); 
    
    for(int i=0;i<button.length;i++ )    
        p2.add(button[i]);


    for(int i=0;i<button.length;i++)    
        button[i].addActionListener(this);
    this.setVisible(true);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
}


@Override
public void actionPerformed(ActionEvent e) {
    // TODO Auto-generated method stub
    String lab=e.getActionCommand();            
    
    if(lab.equals("0"))                            
    {
        sBuilder.append("0");
        text.setText(sBuilder.toString());
    }
}
}运行结果怎么没有显示计算机按钮

没有把p2添加到JS类中