Question

java程序将Button改成JButton,该如何改？

(出现Access restriction: The type 'JButton' is not API (restriction on required library 'C:\Program Files\Java\jre1.8.0_60\lib\rt.jar')
import java.awt.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class student extends Frame {

public student(){
setTitle("登陆界面");
Panel p1 =new Panel();
Panel p2 =new Panel();
Button j =new Button("登陆");
Label l1 =new Label("用户名");
Label l2 =new Label("密码");
TextField t1 =new TextField(10);
TextField t2 =new TextField(10);
p1.add(l1);
p1.add(t1);
p2.add(l2);
p2.add(t2);
add(p1);
add(p2);
add(j);
setLayout(new GridLayout(3,1,3,3));
setVisible(true);
setBounds(300,200,300,200);
addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
dispose();
}
});
}
public static void main(String args[]){
new student();
}
}

Answer 1

可以直接替换

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

public class Student extends JFrame {

  public Student(){
    super("登陆界面");
    JPanel p1 =new JPanel();
    JPanel p2 =new JPanel();
    JButton j =new JButton("登陆");
    JLabel l1 =new JLabel("用户名");
    JLabel l2 =new JLabel("密码");
    JTextField t1 =new JTextField(10);
    JTextField t2 =new JTextField(10);
    p1.add(l1);
    p1.add(t1);
    p2.add(l2);
    p2.add(t2);

    setLayout(new GridLayout(3,1,3,3));
    add(p1);
    add(p2);
    add(j);

    setBounds(300,200,300,200);
    setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    setVisible(true);
  }
  public static void main(String args[]){
    new Student();
  }
}

追问

但是我这里显示这样得错误：Access restriction: The type 'JButton' is not API (restriction on required library 'C:\Program Files\Java\jre1.8.0_60\lib\rt.jar')
到底是什么原因？jdk？

追答

把eclipse里的jre删掉，重新添加一次