组件仅在鼠标悬停在其上时出现

Question

我用 Swing 框架创建了一个 JFrame，我在其中添加了一个 JButton，它将在框架上显示在 JPanel 上创建的表单。

我在按钮上添加了动作侦听器，它正在按预期显示面板；

但是看不到单选按钮和复选框等组件的框。

它们只有在我将鼠标悬停在它们上面时才会出现。

查看单选按钮和复选框中的其他选项：

代码如下：

package codes;

import java.awt.Color;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JTextField;

public class JFrameBackground extends JFrame implements ActionListener
{

    
    private static final long serialVersionUID = 1L;
    
    
    JLabel l1,l2,l3,l4;
    JTextField t1;
    JButton b1;
    JRadioButton r1;
    JComboBox com1;
    JCheckBox chk1;
    
    JPanel p2;
    JButton b;
    
    

    public JFrameBackground() 
    {
        
        p2=new JPanel();
        p2.setLayout(null);
        p2.setBounds(250, 0, 400, 400);
        add(p2);
        
        
        l1 = new JLabel("Name:");
        l1.setBounds(100,10,70,30);
        p2.add(l1);
        
        t1 = new JTextField();
        t1.setBounds(100,50,70,30);
        p2.add(t1);
        
        l2 = new JLabel("Gender:");
        l2.setBounds(100,130,70,30);
        p2.add(l2);
        
        r1 = new JRadioButton("Male");
        r1.setBounds(100,150,70,30);
        p2.add(r1);
        
        r1 = new JRadioButton("Female");
        r1.setBounds(150,150,70,30);
        p2.add(r1);
        
        l3 = new JLabel("Course:");
        l3.setBounds(100,180,70,30);
        p2.add(l3);
        
        chk1= new JCheckBox("Bca");
        chk1.setBounds(100, 200, 70, 30);
        p2.add(chk1);
        
        chk1= new JCheckBox("BBA");
        chk1.setBounds(150, 200, 70, 30);
        p2.add(chk1);
        
        chk1= new JCheckBox("BCOM");
        chk1.setBounds(200, 200, 70, 30);
        p2.add(chk1);
        
        l4 = new JLabel("Country:");
        l4.setBounds(100,220,70,30);
        p2.add(l4);
        
        String name[] = {"India","USA","UK","Rus"};
        
        com1=new JComboBox(name);
        com1.setBounds(100, 250, 70, 30);
        p2.add(com1);
        
        b1= new JButton("Submit");
        b1.setBounds(140, 300, 90, 30);
        p2.add(b1);
        
        
        
        
        b =new JButton("Show form");
        b.setBounds(0, 4, 190, 40);
        b.setFocusPainted(false);
        b.setBorderPainted(false);
        b.addActionListener(this);
        add(b);
        
        b.addMouseListener(new MouseAdapter() 
        {
            public void mouseClicked(MouseEvent me)
            {
                
                p2.setVisible(true);
                
                
            }
        });
        
        
        
        Container c=getContentPane();
        c.setBackground(Color.gray);
        setBounds(170, 100, 1250, 500);
        
        setLayout(null);
        setVisible(true);
    }


    public static void main(String[] args) 
    {
        
        new JFrameBackground();
        

    }

    public void actionPerformed(ActionEvent arg0) 
    {
        
        
    }

}

Answer 1

左侧的组件太大，因此与复选框重叠。这就是为什么它们没有正确显示的原因。所以像这样移动正确的组件：

 r1.setBounds(170, 150, 70, 30);
 chk1.setBounds(170, 200, 70, 30);              
 chk1.setBounds(240, 200, 70, 30);

它会起作用。

Answer 2

这似乎效果更好。

我修复了单选按钮和复选框的位置。
我对复选框和单选按钮对象使用了不同的引用（r1、r2、chk1、chk2、chk3）

我为单选按钮添加了一个按钮组。

 import java.awt.Color;
 import java.awt.Container;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;

 import javax.swing.JButton;
 import javax.swing.JCheckBox;
 import javax.swing.JComboBox;
 import javax.swing.JFrame;
 import javax.swing.JLabel;
 import javax.swing.JPanel;
 import javax.swing.JRadioButton;
 import javax.swing.JTextField;

 import javax.swing.ButtonGroup;

 public class JFrameBackground extends JFrame implements ActionListener
 {


     private static final long serialVersionUID = 1L;


     JLabel l1,l2,l3,l4;
     JTextField t1;
     JButton b1;
     JRadioButton r1, r2;
     JComboBox com1;
     JCheckBox chk1, chk2, chk3;

     JPanel p2;
     JButton b;



     public JFrameBackground() 
     {

         p2=new JPanel();
         p2.setLayout(null);
         p2.setBounds(250, 0, 400, 400);
         add(p2);


         l1 = new JLabel("Name:");
         l1.setBounds(100,10,70,30);
         p2.add(l1);

         t1 = new JTextField();
         t1.setBounds(100,50,70,30);
         p2.add(t1);

         l2 = new JLabel("Gender:");
         l2.setBounds(100,130,70,30);
         p2.add(l2);

         r1 = new JRadioButton("Male");
         r1.setBounds(100,150,70,30);
         p2.add(r1);

         r2 = new JRadioButton("Female");
         r2.setBounds(180,150,70,30);
         p2.add(r2);

         ButtonGroup bg=new ButtonGroup();    
         bg.add(r1);
         bg.add(r2); 

         l3 = new JLabel("Course:");
         l3.setBounds(100,180,70,30);
         p2.add(l3);

         chk1= new JCheckBox("Bca");
         chk1.setBounds(100, 200, 70, 30);
         p2.add(chk1);

         chk2= new JCheckBox("BBA");
         chk2.setBounds(180, 200, 70, 30);
         p2.add(chk2);

         chk3= new JCheckBox("BCOM");
         chk3.setBounds(260, 200, 70, 30);
         p2.add(chk3);

         l4 = new JLabel("Country:");
         l4.setBounds(100,220,70,30);
         p2.add(l4);

         String name[] = {"India","USA","UK","Rus"};

         com1=new JComboBox(name);
         com1.setBounds(100, 250, 70, 30);
         p2.add(com1);

         b1= new JButton("Submit");
         b1.setBounds(140, 300, 90, 30);
         p2.add(b1);




         b =new JButton("Show form");
         b.setBounds(0, 4, 190, 40);
         b.setFocusPainted(false);
         b.setBorderPainted(false);
         b.addActionListener(this);
         getContentPane().add(b);

         b.addMouseListener(new MouseAdapter() 
         {
             public void mouseClicked(MouseEvent me)
             {

                 p2.setVisible(true);


             }
         });



         Container c=getContentPane();
         c.setBackground(Color.gray);
         setBounds(170, 100, 1250, 500);

         setLayout(null);
         setVisible(true);
     }


     public static void main(String[] args) 
     {

         new JFrameBackground();


     }

     public void actionPerformed(ActionEvent arg0) 
     {


     }

 }

组件仅在鼠标悬停在其上时出现

Components appear only when mouse hovers over them

java

swing

jframe

layout-manager