Java - JFrame根本不顯示其內容

Question

對我而言，這是第一篇文章。我是科學學士學位第一年的學生。

我只是爲一個任務創建了一個基本的圖形用戶界面，並且由於某種原因，我無法看到我的生活，我創建的JFrames之一，Register Class的一個實例在被調用時顯示爲完全空白從登錄類中的註冊按鈕動作監聽器...

我也有一個單獨的主類，它包含Main方法並調用Login類。 Login Class JFrame正常工作，如前所述，只有在Login Class'Register按鈕動作偵聽器中調用Register Class時纔會出現問題。程序中的所有其他JFrames也可以正常工作。

我試圖直接從main調用Register Class，它有相同的問題，儘管我試圖將其減少到最基本的形式，並且它仍然不顯示任何空白的無色JFrame。

這裏是代碼（未完成但按原樣工作）。我爲我的sl ap道歉，但我是一個完整的初學者。

任何人都可以看到它有什麼問題嗎？

在此先感謝！

package guitest; 

    import java.awt.Color; 
    import java.awt.Component; 
    import java.awt.FlowLayout; 
    import java.awt.event.ActionEvent; 
    import java.awt.event.ActionListener; 
    import java.io.BufferedWriter; 
    import java.io.FileWriter; 
    import java.awt.event.*; 
    import java.io.*; 
    import javax.swing.*; 

    public class Register extends JFrame{ 

     JButton regSubmit = new JButton("Submit"); 

     JTextField email = new JTextField(); 
     JTextField name = new JTextField(); 
     JTextField Address1 = new JTextField(); 
     JTextField Address2 = new JTextField(); 

     JPasswordField password1 = new JPasswordField(); 
     JPasswordField password2 = new JPasswordField(); 

     String nameTxt = email.getText(); 
     String passTxt = password1.getText(); 
     String info = ""; 

     FlowLayout layout1 = new FlowLayout();  

     public void Reg(){ 
      this.setTitle("La Volpe Registration"); 
      this.setLayout(layout1);  
      this.add(Address1); 
      this.add(Address2); 
      this.add(email); 
      this.add(password1); 
      this.add(password2); 
      this.add(name); 
      this.add(regSubmit); 
      this.getContentPane().setBackground(Color.green); 
      this.setSize(370, 160); 

      regSubmit.addActionListener(new java.awt.event.ActionListener() { 
       public void actionPerformed(java.awt.event.ActionEvent evt) { 
        regSubmitActionPerformed(evt); 
       } 

       private void regSubmitActionPerformed(java.awt.event.ActionEvent evt) { 

       String name = email.getText(); 
       String pass = password1.getText(); 
       String info = ""; 

       System.out.println("registering..."); 

       boolean eof; 

       try{ 
        // Create file 
        FileWriter file = new FileWriter("\\regdata.txt"); 
        BufferedWriter out = new BufferedWriter(file); 
        out.write("\n"+nameTxt+", "+passTxt); 
       } 

       catch (Exception e){ 
       } 
      } 
     }); 
     this.setVisible(true); 
    }  
} 

---

並鏈接到它的類...

---

package guitest; 

    import java.awt.Color; 
    import java.awt.Component; 
    import java.awt.FlowLayout; 
    import java.awt.event.ActionEvent; 
    import java.awt.event.ActionListener; 
    import java.io.BufferedWriter; 
    import java.io.FileWriter; 
    import java.awt.event.*; 
    import java.io.*; 
    import javax.swing.*; 

    /** 
    * @author david 
    */ 

    public class Login { 

    JFrame loginFrame = new JFrame(); 
    Register reg3 = new Register(); 

    JButton submit = new JButton("Submit"); 
    JButton clear = new JButton("Clear"); 
    JButton register = new JButton ("Register with Us"); 

    JPasswordField pass = new JPasswordField(20); 
    JTextField email = new JTextField(20); 
    JLabel em = new JLabel("Email Address: "); 
    JLabel pw = new JLabel("Password: "); 

    String pathname; 
    String line; 
    String [] records = new String [1000]; 
    int count = 0; 

    FlowLayout layout1 = new FlowLayout(); 

     public Login(){ 

      //Adds Email label and text field 
      loginFrame.add(em); 
      loginFrame.add(email); 

      //Adds password label and field 
      loginFrame.add(pw); 
      loginFrame.add(pass); 

      //Adds buttons 
      loginFrame.add(submit); 
      loginFrame.add(clear); 
      loginFrame.add(register); 

      loginFrame.getContentPane().setBackground(Color.green); 

      loginFrame.setLayout(layout1); 

      loginFrame.setSize(370, 160); 

      loginFrame.setTitle("La Volpe - Login"); 

      submit.addActionListener(new java.awt.event.ActionListener() { 
       public void actionPerformed(java.awt.event.ActionEvent evt) { 
        submitActionPerformed(evt);  
       }    

       private void submitActionPerformed(java.awt.event.ActionEvent evt){           
       String emailadd = email.getText(); 
       String password = pass.getText(); 
       pathname = "\\regdata.txt"; 

       boolean eof; 

       try{ 
        FileReader file = new FileReader(pathname); 
        BufferedReader buff = new BufferedReader(file); 

        eof = false; // set the eof boolean to false 

         while (!eof){ 
         line = buff.readLine(); 
         if (line == null){ // test to see if the end of file has been reached 
         eof = true; // if the end of file has been found set the eof Boolean to true 
         } 
         else{ 
         // end of file not reached so move the contents of the line to the records 
         //array 
         records[count] = line; 
         count ++; 
         System.out.println(line); // print out the new line input for error checking 
         } 
        }  
        buff.close(); 
       } 
       catch (IOException e){ 
        System.out.println("Error -- "+ e.toString()); 
       } 

       boolean notTrue = false; 

       for (int i = 0; i < count; i++) {  
        if ((!notTrue)&&((emailadd + "," + password).equals(records[i]))) { 
         FoodSelectionMain loggedIn = new FoodSelectionMain(); 
         loggedIn.setVisible(true); 
        } 
       } 
       if (!notTrue){ 
        JOptionPane.showInputDialog("Please check your login " 
        + "and try again. If you are a new user, please " 
        + "register by pressing the 'REGISTER' button"); 
       } 
      } 

     }); 

     // TODO add your handling code here: 


     clear.addActionListener(new java.awt.event.ActionListener() { 
      public void actionPerformed(java.awt.event.ActionEvent evt) { 
       clearActionPerformed(evt); 
      } 

      public void clearActionPerformed(java.awt.event.ActionEvent evt){ 
       email.setText(null); 
       pass.setText(null); 
      } 

     }); 
     register.addActionListener(new java.awt.event.ActionListener() { 
      public void actionPerformed(java.awt.event.ActionEvent evt) { 
       registerActionPerformed(evt); 
      } 

      public void registerActionPerformed(java.awt.event.ActionEvent evt){ 
       reg3.setVisible(true); 
        System.out.println("Register pressed"); 
      } 
     }); 
     loginFrame.setVisible(true); 
    } 
} 

Answer 1

試試這個， 註冊類，糾正構造函數名稱從註冊登記（）（） 。

構建GUI應用程序

1. 創建容器的子類的對象之前，請這幾個原則在你的心中。

2. 考慮所有在容器中作爲實例變量的組件。

3. 在構造函數的外部設置這些實例變量和事件處理方法（例如setComponent（），setHandler（）等），但是從構造函數中執行這些方法調用。

4. 現在主要使用這個......

。

EventQueue.invokeLater(new Runnable() { 

    public void run() { 
     Myframe f = new Myframe(); 
     f.setVisible(true); 
    } 
}