如何在单击或选中时消失的JTextArea上添加消息？
[英]How do i add a message on a JTextArea that disappears when clicked or selected?
问题描述
my question is very simple but I but i don't know what it is 
我的问题很简单，但我不知道它是什么
I have a program, in java, like so 我有一个程序，在java中，就像这样
and I want to add on the JTextArea's a short message that disappeares when clicked or selected, like when you login on facebook 我想在JTextArea上添加一条短信，在点击或选中时会消失，就像你在facebook上登录一样
The JTextArea i want is for example the one below the "Startind Date:" the JTextArea is called textAreaStartindDate 我想要的JTextArea例如是“Startind Date：”下面的那个JTextArea被称为textAreaStartindDate
this is my code so far. 到目前为止这是我的代码。 i used the netbeans built in design option 我使用了netbeans内置的设计选项
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
} }
without using the obvious 没有使用明显的
2 个解决方案
解决方案1
0 2017-06-01 19:17:34
In general you can use an ActionListener or a MouseListener. 通常，您可以使用ActionListener或MouseListener。 For you did not post any code, we cannot help you out exactly. 因为你没有发布任何代码，我们无法帮助你。 But maybe this post helps: Onclick for TextField 但也许这篇文章可以帮助： Onclick for TextField
解决方案2
0 2017-06-01 19:36:27
Add a default text when initializing the JTextArea . 初始化JTextArea时添加默认文本。 Then add a FocusListener . 然后添加一个FocusListener 。 like below: 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");
}
});
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