關於Java GUI並清除JFrame以顯示新內容？

Question

我正在學習Java和GUI。我有一些問題，首先是創建JFrame的子類和JFrame的實例之間有什麼主要區別。看起來像一個子類更強大？我也想知道是否有必要使用創建GUI時這個代碼：

Container contentPane = getContentPane(); 
contentPane.setLayot(new Flowlayout()); 

添加我的GUI類，這是一個簡單的測試，到目前爲止，到我手的任務。當用戶輸入。文本框中的一些文本，然後按按鈕繼續下一步，我該如何清除框架並顯示新內容，或者有沒有一種特殊的方法可以在Java中執行此操作？我想最好是使用相同的窗口而不是創建新的！？幫助ID preciated！由於

// Gui class 

    import java.awt.FlowLayout; // layout 
    import java.awt.event.ActionListener; // listener 
    import java.awt.event.ActionEvent; // event 

    import javax.swing.JFrame; // windows properties 
    import javax.swing.JLabel; // row of text 
    import javax.swing.JTextField; // enter text 
    import javax.swing.JOptionPane; // pop up dialog 
    import javax.swing.JButton; // buttons 

    // import.javax.swing.*; 

    public class Gui extends JFrame { 

    private JLabel text1; 
    private JTextField textInput1; 
    private JTextField textInput2; 
    private JButton nextButton; 

    // constructor creates the window and it's components 
    public Gui() { 
     super("Bank"); // title 
     setLayout(new FlowLayout()); // set default layout 

     text1 = new JLabel("New customer"); 
     add(text1); 

     textInput1 = new JTextField(10); 
     add(textInput1); 

     nextButton = new JButton("Continue"); 
     add(nextButton); 

     // create object to handle the components (action listener object) 
     frameHandler handler = new frameHandler(); 
     textInput1.addActionListener(handler); 
     nextButton.addActionListener(handler); 
    } 

    // handle the events (class inside another class inherits contents from class outside) 
    private class frameHandler implements ActionListener { 

     public void actionPerformed(ActionEvent event){ 

      String input1 = ""; 

      // check if someone hits enter at first textfield 
      if(event.getSource() == textInput1){ 
       input1 = String.format(event.getActionCommand()); 
       JOptionPane.showMessageDialog(null, input1); 
      } 

      else if(event.getSource() == nextButton){ 
       // ?? 
      } 
     } 
    } 
} 

Answer 1

這個小代碼可以幫助你交代的事情：

import java.awt.event.*; 
import javax.swing.*; 

public class FrameDisplayTest implements ActionListener 
{ 
    /* 
    * Creating an object of JFrame instead of extending it 
    * has no side effects. 
    */ 
    private JFrame frame; 
    private JPanel panel, panel1; 
    private JTextField tfield; 
    private JButton nextButton, backButton; 

    public FrameDisplayTest() 
    { 
     frame = new JFrame("Frame Display Test"); 
     // If you running your program from cmd, this line lets it comes 
     // out of cmd when you click the top-right RED Button. 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

     panel = new JPanel(); 
     panel1 = new JPanel(); 

     tfield = new JTextField(10); 

     nextButton = new JButton("NEXT"); 
     backButton = new JButton("BACK"); 
     nextButton.addActionListener(this); 
     backButton.addActionListener(this); 

     panel.add(tfield); 
     panel.add(nextButton); 
     panel1.add(backButton); 

     frame.setContentPane(panel); 
     frame.setSize(220, 220); 
     frame.setVisible(true); 
    } 

    public void actionPerformed(ActionEvent ae) 
    { 
     JButton button = (JButton) ae.getSource(); 
     if (tfield.getText().length() > 0) 
     { 
      if (button == nextButton) 
      { 
       /* 
       * this will remove the first panel 
       * and add the new panel to the frame. 
       */ 
       frame.remove(panel); 
       frame.setContentPane(panel1); 
      } 
      else if (button == backButton) 
      { 
       frame.remove(panel1); 
       frame.setContentPane(panel); 
      } 
      frame.validate(); 
      frame.repaint(); // prefer to write this always. 
     } 
    } 

    public static void main(String[] args) 
    { 
     /* 
     * This is the most important part ofyour GUI app, never forget 
     * to schedule a job for your event dispatcher thread : 
     * by calling the function, method or constructor, responsible 
     * for creating and displaying your GUI. 
     */ 
     SwingUtilities.invokeLater(new Runnable() 
     { 
      @Override 
      public void run() 
      { 
       new FrameDisplayTest(); 
      } 
     }); 
    } 
} 

Answer 2

如果你想切換（ADD然後刪除）JComponents

，那麼你必須

1）添加/刪除JComponents然後調用

revalidate(); 
repaint()// sometimes required 

2）更好的和最容易的選擇將器具CardLayout

Answer 3

如果你的要求是做一個嚮導，單擊下一步和上一個按鈕面板，並單擊顯示一些組件下一首/上一個按鈕。你可以嘗試使用CardLayout。

的CardLayout管理共享相同的顯示空間的兩個或更多個部件（通常的JPanel實例）。 CardLayout讓用戶在組件之間進行選擇。

How to Use CardLayout

Answer 4

如果你的類擴展JFrame中，你可以這樣做：

getContentPane().removeAll();