如何在單擊或選擇時消失的JTextArea上添加消息？

我的問題很簡單，但我，但我不知道它是什麼如何在單擊或選擇時消失的JTextArea上添加消息？

我有一個計劃，在Java中，像這樣

，我想在JTextArea中的一個加單擊或選擇的時候，當你登錄的Facebook一樣，disappeares短消息

的JTextArea中我要的是例如下面的「啓動一個ind日期：「JTextArea被稱爲textAreaStartindDate

這是我的代碼到目前爲止。我使用內置的設計選項

public class CreateEventUI extends javax.swing.JFrame { 

private static final long serialVersionUID = 7526472295622776147L; 

//GUARDAR EVENTOS EM REGISTOEVENTOS 

/** 
* Creates new form CriarEventoUI 
*/ 
public CreateEventUI() { 
    super("Create an Event"); 
    setResizable(false); 
    initComponents(); 
    setDefaultCloseOperation(DISPOSE_ON_CLOSE); 
    setVisible(true); 
} 

/** 
* 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() { 

    labelChooseTypeOfEvent = new javax.swing.JLabel(); 
    comboBoxTypeOfEvent = new javax.swing.JComboBox<>(); 
    labelInsertTypeOfData = new javax.swing.JLabel(); 
    labelTitle = new javax.swing.JLabel(); 
    labelDescription = new javax.swing.JLabel(); 
    jScrollPane1 = new javax.swing.JScrollPane(); 
    textAreaDescription = new javax.swing.JTextArea(); 
    textFieldTitle = new javax.swing.JTextField(); 
    labelStartingDate = new javax.swing.JLabel(); 
    labelStartSubmissionDate = new javax.swing.JLabel(); 
    labelEndDate = new javax.swing.JLabel(); 
    labelEndSubmissionDate = new javax.swing.JLabel(); 
    labelPlace = new javax.swing.JLabel(); 
    textFieldPlace = new javax.swing.JTextField(); 
    buttonConfirm = new javax.swing.JButton(); 
    buttonCancel = new javax.swing.JButton(); 
    textFieldStartingDate = new javax.swing.JTextField(); 
    jTextField3 = new javax.swing.JTextField(); 
    jTextField2 = new javax.swing.JTextField(); 
    jTextField4 = new javax.swing.JTextField(); 

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 

    labelChooseTypeOfEvent.setText("Choose the type of event"); 

    comboBoxTypeOfEvent.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "Congress" , "Exposition"})); 

    labelInsertTypeOfData.setText("insert the data"); 

    labelTitle.setText("Title"); 

    labelDescription.setText("Description"); 

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

    labelStartingDate.setText("Starting date:"); 

    labelStartSubmissionDate.setText("starting date for submissions:"); 

    labelEndDate.setText("End date:"); 

    labelEndSubmissionDate.setText("Ending date for submissions:"); 

    labelPlace.setText("place"); 

    buttonConfirm.setText("Confirm"); 
    buttonConfirm.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      buttonConfirmActionPerformed(evt); 
     } 
    }); 

    buttonCancel.setText("Cancel"); 
    buttonCancel.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      buttonCancelActionPerformed(evt); 
     } 
    }); 

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

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); 
    getContentPane().setLayout(layout); 
    layout.setHorizontalGroup(
     layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
     .addGroup(layout.createSequentialGroup() 
      .addGap(25, 25, 25) 
      .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
       .addComponent(labelInsertTypeOfData) 
       .addGroup(layout.createSequentialGroup() 
        .addComponent(labelChooseTypeOfEvent) 
        .addGap(18, 18, 18) 
        .addComponent(comboBoxTypeOfEvent, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE)) 
       .addGroup(layout.createSequentialGroup() 
        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false) 
         .addGroup(layout.createSequentialGroup() 
          .addComponent(labelTitle) 
          .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
          .addComponent(textFieldTitle)) 
         .addComponent(labelDescription) 
         .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 222, Short.MAX_VALUE) 
         .addGroup(layout.createSequentialGroup() 
          .addComponent(labelPlace) 
          .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
          .addComponent(textFieldPlace))) 
        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
         .addGroup(layout.createSequentialGroup() 
          .addGap(18, 18, 18) 
          .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
           .addComponent(labelStartSubmissionDate) 
           .addComponent(labelStartingDate) 
           .addComponent(textFieldStartingDate, javax.swing.GroupLayout.PREFERRED_SIZE, 150, javax.swing.GroupLayout.PREFERRED_SIZE) 
           .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, 150, javax.swing.GroupLayout.PREFERRED_SIZE)) 
          .addGap(40, 40, 40) 
          .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
           .addComponent(labelEndDate) 
           .addComponent(labelEndSubmissionDate) 
           .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, 150, javax.swing.GroupLayout.PREFERRED_SIZE) 
           .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, 150, javax.swing.GroupLayout.PREFERRED_SIZE))) 
         .addGroup(layout.createSequentialGroup() 
          .addGap(173, 173, 173) 
          .addComponent(buttonConfirm) 
          .addGap(87, 87, 87) 
          .addComponent(buttonCancel))))) 
      .addContainerGap(13, Short.MAX_VALUE)) 
    ); 
    layout.setVerticalGroup(
     layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
     .addGroup(layout.createSequentialGroup() 
      .addGap(28, 28, 28) 
      .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
       .addComponent(labelChooseTypeOfEvent) 
       .addComponent(comboBoxTypeOfEvent, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
      .addGap(23, 23, 23) 
      .addComponent(labelInsertTypeOfData) 
      .addGap(18, 18, 18) 
      .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
       .addGroup(layout.createSequentialGroup() 
        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
         .addComponent(labelTitle) 
         .addComponent(textFieldTitle, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
        .addComponent(labelDescription) 
        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) 
        .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 92, javax.swing.GroupLayout.PREFERRED_SIZE)) 
       .addGroup(layout.createSequentialGroup() 
        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
         .addComponent(labelStartingDate) 
         .addComponent(labelEndDate)) 
        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
         .addGroup(layout.createSequentialGroup() 
          .addGap(52, 52, 52) 
          .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
           .addComponent(labelStartSubmissionDate) 
           .addComponent(labelEndSubmissionDate)) 
          .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED) 
          .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
           .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
           .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))) 
         .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
          .addComponent(textFieldStartingDate, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
          .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))))) 
      .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED) 
      .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
       .addComponent(labelPlace) 
       .addComponent(textFieldPlace, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addComponent(buttonConfirm) 
       .addComponent(buttonCancel)) 
      .addContainerGap(17, Short.MAX_VALUE)) 
    ); 

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

private void buttonConfirmActionPerformed(java.awt.event.ActionEvent evt) {            
    // TODO add your handling code here: 
}            

private void buttonCancelActionPerformed(java.awt.event.ActionEvent evt) {            
    dispose(); 
}            

private void textFieldStartingDateActionPerformed(java.awt.event.ActionEvent evt) {              
    // TODO add your handling code here: 
}              

// Variables declaration - do not modify      
private javax.swing.JButton buttonCancel; 
private javax.swing.JButton buttonConfirm; 
private javax.swing.JComboBox<String> comboBoxTypeOfEvent; 
private javax.swing.JScrollPane jScrollPane1; 
private javax.swing.JTextField jTextField2; 
private javax.swing.JTextField jTextField3; 
private javax.swing.JTextField jTextField4; 
private javax.swing.JLabel labelChooseTypeOfEvent; 
private javax.swing.JLabel labelDescription; 
private javax.swing.JLabel labelEndDate; 
private javax.swing.JLabel labelEndSubmissionDate; 
private javax.swing.JLabel labelInsertTypeOfData; 
private javax.swing.JLabel labelPlace; 
private javax.swing.JLabel labelStartSubmissionDate; 
private javax.swing.JLabel labelStartingDate; 
private javax.swing.JLabel labelTitle; 
private javax.swing.JTextArea textAreaDescription; 
private javax.swing.JTextField textFieldPlace; 
private javax.swing.JTextField textFieldStartingDate; 
private javax.swing.JTextField textFieldTitle; 
// End of variables declaration

}

在NetBeans不使用明顯

來源

2017-06-01 skidils

你可以添加你的代碼到目前爲止嗎？ –

搜索水印textfield/textarea或[帶默認消息的文本字段]（https://stackoverflow.com/questions/14916255/how-to-display-a-default-message-in-jtextfield-java） – matoni

你在問關於JTextArea或JTextField（或兩者）？ – Pshemo

一般來說，你可以使用一個ActionListener或MouseListener的。因爲您沒有發佈任何代碼，我們無法完全幫助您。但也許這個職位幫助： Onclick for TextField

來源

2017-06-01 19:17:34

我已經用代碼編輯過，對不起我想避免顯而易見的.setText（「」）當我選擇JTextArea – skidils

因此，如果.setText（「」）太明顯，你究竟想要什麼？ –

當初始化JTextArea時添加默認文本。然後添加一個FocusListener。像如下：

textAreaDescription = new javax.swing.JTextArea("Description"); 
//jScrollPane1.setViewportView(textAreaDescription); 
textAreaDescription.addFocusListener(new FocusListener() { 
    public void focusGained(FocusEvent e) { 
     textAreaDescription.setText(""); 
    } 

    public void focusLost(FocusEvent e) { 
     textAreaDescription.setText("Description"); 
    } 
});

來源

2017-06-01 19:36:27 Blasanka

如何在單擊或選擇時消失的JTextArea上添加消息？

回答

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