IllegalArgumentExceptionウィンドウをコンテナに追加しています。

Question

私はJava swingを初めて使用しています。メインクラスからJframeを呼び出すときに問題があります。それは重複かもしれませんが、私のコードがなぜ機能しないのかを知ることはできません。だから私はここに投稿しています。

Mainclass

public static void main(String[] args) { 
    // TODO code application logic here 
    SwingUtilities.invokeLater(new Runnable() { 

     @Override 
     public void run() { 
      SendMail sendMail = new SendMail(); 
      JFrame frame = new JFrame();         
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
      frame.add(sendMail,BorderLayout.CENTER); 
      frame.pack(); 
      frame.setVisible(true); 
     } 
    }); 

} 

JFrameの

public class SendMail extends javax.swing.JFrame { 

/** 
* Creates new form SendMail 
*/ 
public SendMail() { 
    initComponents(); 
} 

/** 
* This method is called from within the constructor to initialize the form. 
* WARNING: Do NOT modify this code. The content of this method is always 
* regenerated by the Form Editor. 
*/ 
@SuppressWarnings("unchecked") 
// <editor-fold defaultstate="collapsed" desc="Generated Code">       
private void initComponents() { 

    jFileChooser1 = new javax.swing.JFileChooser(); 
    jFileChooser2 = new javax.swing.JFileChooser(); 
    jButton2 = new javax.swing.JButton(); 
    jPanel1 = new javax.swing.JPanel(); 
    to = new javax.swing.JTextField(); 
    toLabel = new javax.swing.JLabel(); 
    toCc = new javax.swing.JLabel(); 
    toBcc = new javax.swing.JLabel(); 
    cc = new javax.swing.JTextField(); 
    bcc = new javax.swing.JTextField(); 
    jPanel2 = new javax.swing.JPanel(); 
    jScrollPane1 = new javax.swing.JScrollPane(); 
    jTextArea1 = new javax.swing.JTextArea(); 
    sendButton = new javax.swing.JButton(); 
    fileName = new javax.swing.JTextField(); 
    attach = new javax.swing.JButton(); 

    jButton2.setText("jButton2"); 

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 

    to.setText("TO"); 
    to.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      toActionPerformed(evt); 
     } 
    }); 

    toLabel.setText("TO "); 

    toCc.setText("CC"); 

    toBcc.setText("BCC"); 

    cc.setText("CC"); 
    cc.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      ccActionPerformed(evt); 
     } 
    }); 

    bcc.setText("BCC"); 

    javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1); 
    jPanel1.setLayout(jPanel1Layout); 
    jPanel1Layout.setHorizontalGroup(
     jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
     .addGroup(jPanel1Layout.createSequentialGroup() 
      .addContainerGap() 
      .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false) 
       .addComponent(toBcc, javax.swing.GroupLayout.DEFAULT_SIZE, 142, Short.MAX_VALUE) 
       .addComponent(toCc, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
       .addComponent(toLabel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)) 
      .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
      .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false) 
       .addComponent(to) 
       .addComponent(cc) 
       .addComponent(bcc, javax.swing.GroupLayout.DEFAULT_SIZE, 199, Short.MAX_VALUE)) 
      .addContainerGap()) 
    ); 
    jPanel1Layout.setVerticalGroup(
     jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
     .addGroup(jPanel1Layout.createSequentialGroup() 
      .addContainerGap() 
      .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
       .addComponent(to, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addComponent(toLabel)) 
      .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
      .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
       .addComponent(toCc) 
       .addComponent(cc, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
      .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
      .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
       .addComponent(toBcc) 
       .addComponent(bcc, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
      .addContainerGap(20, Short.MAX_VALUE)) 
    ); 

    jTextArea1.setColumns(20); 
    jTextArea1.setRows(5); 
    jScrollPane1.setViewportView(jTextArea1); 

    sendButton.setText("Send"); 
    sendButton.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      sendButtonActionPerformed(evt); 
     } 
    }); 

    attach.setText("Attach"); 
    attach.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      attachActionPerformed(evt); 
     } 
    }); 

    javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2); 
    jPanel2.setLayout(jPanel2Layout); 
    jPanel2Layout.setHorizontalGroup(
     jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
     .addGroup(jPanel2Layout.createSequentialGroup() 
      .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 244, javax.swing.GroupLayout.PREFERRED_SIZE) 
      .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
      .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
       .addComponent(sendButton, javax.swing.GroupLayout.DEFAULT_SIZE, 150, Short.MAX_VALUE) 
       .addGroup(jPanel2Layout.createSequentialGroup() 
        .addComponent(fileName) 
        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
        .addComponent(attach, javax.swing.GroupLayout.PREFERRED_SIZE, 27, javax.swing.GroupLayout.PREFERRED_SIZE)))) 
    ); 
    jPanel2Layout.setVerticalGroup(
     jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
     .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 197, Short.MAX_VALUE) 
     .addGroup(jPanel2Layout.createSequentialGroup() 
      .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
       .addComponent(fileName, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addComponent(attach)) 
      .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
      .addComponent(sendButton)) 
    ); 

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); 
    getContentPane().setLayout(layout); 
    layout.setHorizontalGroup(
     layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
     .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
     .addComponent(jPanel2, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
    ); 
    layout.setVerticalGroup(
     layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
     .addGroup(layout.createSequentialGroup() 
      .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
      .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED) 
      .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
      .addContainerGap()) 
    ); 

    pack(); 
}// </editor-fold>       

私はこの問題を解決するのに役立ちます。前もって感謝します。

public class SendMail extends javax.swing.JPanel 

へ

Answer 1

スイッチ

public class SendMail extends javax.swing.JFrame 

あなたは別のJFrameのを追加することはできません。