为什么我的组件不可见？

我可以看到已定义大小的窗口，但窗口中没有任何组件。为什么组件不可见？

我有单独的方法用于创建，初始化和添加组件。这些方法是从构造函数调用的。标题和定义大小的窗口在输出中可见。我错过了什么？

package swing_basics; 

import java.awt.FlowLayout; 
import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPasswordField; 
import javax.swing.JTextField; 

public class MySwingDemo extends JFrame { 

    JLabel lblName, lblPassword; //Declaration of variables 
    JTextField txtfName; 
    JPasswordField pwdfPassword; 
    JButton btnSubmit, btnCancel, btnReset; 

    public void createComponents(){ //method to initialise the components 

     lblName = new JLabel(); 
     lblPassword = new JLabel(); 
     txtfName = new JTextField(); 
     pwdfPassword = new JPasswordField(); 
     btnSubmit = new JButton(); 
     btnCancel = new JButton(); 
     btnReset = new JButton(); 
    } 

    public void setComponents(){ //method to set the components 
     setVisible(true); 
     setSize(400, 400); 
     setTitle("My Swing Demo"); 
     setLayout(new FlowLayout()); 

     lblName.setText("Name"); 
     lblPassword.setText("Password"); 

     txtfName.setText("Name");// try 

     pwdfPassword.setText("Password"); 

     btnSubmit.setText("Submit"); 
     btnCancel.setText("Cancel"); 
     btnReset.setText("Reset"); 
    } 

    public void addComponents(JFrame frame){ //method to add the components 
     frame.add(lblName); 
     frame.add(txtfName); 

     frame.add(lblPassword); 
     frame.add(pwdfPassword); 

     frame.add(btnSubmit); 
     frame.add(btnCancel); 
     frame.add(btnReset); 
    } 

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

    public MySwingDemo() { //Constructor 
     createComponents(); 
     setComponents(); 
     addComponents(this); 
    } 

}

来源

2016-12-18 Aman Sw

这是操作的，你设置frame可见您添加（和设置）之前，你的组件的顺序。在之后，请将setVisible(true);移至您已设置好组件。和，请确保您致电addComponents(this);之前您拨打setComponents();。

像

public MySwingDemo() { // Constructor createComponents(); addComponents(this); setComponents(); }

和我还想添加默认frame关闭操作

public void setComponents() { // method to set the components setSize(400, 400); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setTitle("My Swing Demo"); setLayout(new FlowLayout()); lblName.setText("Name"); lblPassword.setText("Password"); txtfName.setText("Name");// try pwdfPassword.setText("Password"); btnSubmit.setText("Submit"); btnCancel.setText("Cancel"); btnReset.setText("Reset"); setVisible(true); }

来源

2016-12-18 05:25:29

为什么我的组件不可见？

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