添加動作監聽器

Question

我創建了一個JList和JTextField。在我的JList中，我寫了幾個選擇選項，並且我希望所選選項名稱出現在JTextField中。

什麼代碼，我需要在jTextField2動作監聽這麼寫，例如，如果我選擇計算機它會顯示電腦在JTextField

的ListModel

jList1Model = new DefaultComboBoxModel (new String[] { "Computer","Mouse","HDD"}); 

jList1 = new JList(); 
getContentPane().add(jList1); 
jList1.setModel(jList1Model); 
jList1.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); 
jTextField2 = new JTextField(); 

getContentPane().add(jTextField2); 
jTextField2.setEditable(false); 
jTextField2.addActionListener(new ActionListener() { 
    public void actionPerformed(ActionEvent evt) { 
    } 
}); 

Answer 1

javax.swing.JComboBox cboSelect = new javax.swing.JComboBox(); 
 
javax.swing.JTextField tfResult = new javax.swing.JTextField(); 

cboSelect.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Computer", "Mouse", "HDD" })); 
     cboSelect.addItemListener(new java.awt.event.ItemListener() { 
      public void itemStateChanged(java.awt.event.ItemEvent evt) { 
       tfResult.setText(cboSelect.getSelectedItem().toString()); 
      } 
     }); 

Answer 2

這個怎麼樣：

jList1t.addListSelectionListener(new ListSelectionListener() { 
     public void valueChanged(ListSelectionEvent e) { 
      jTextField2.setText((String) jList1.getSelectedValue()); 
     } 
    }); 

（和jTextField2中必須final！）

Answer 3

您需要添加ListSelectionListener這將在變化列表選擇炒魷魚：

jList1.addListSelectionListener(new ListSelectionListener() { 
     public void valueChanged(ListSelectionEvent evt) { 
      jList1ValueChanged(evt); 
     } 
    }); 

和ListSelectionEvent

private void jList1ValueChanged(ListSelectionEvent evt) { 

    if(!jList1.getValueIsAdjusting()) 
    { 
    jTextField2.setText((String) jList1.getSelectedValue()); 
    } 
    } 

這裏是一個簡短的例子：

import javax.swing.AbstractListModel; 
import javax.swing.JFrame; 
import javax.swing.JList; 
import javax.swing.JPanel; 
import javax.swing.JTextField; 
import javax.swing.SwingUtilities; 
import javax.swing.WindowConstants; 
import javax.swing.event.ListSelectionEvent; 
import javax.swing.event.ListSelectionListener; 

public class JListTest { 
    private JList jList1; 
    private JPanel jPanel1; 
    private JTextField jTextField2; 
    private JFrame frame; 


    public JListTest() { 
     initComponents(); 
    } 

    private void initComponents() { 

     jPanel1 = new JPanel(); 
     jList1 = new JList(); 
     jTextField2 = new JTextField(); 
     frame =new JFrame(); 
     frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); 

     jList1.setModel(new AbstractListModel() { 
      String[] strings = { "Computer", "Mouse", "HDD" }; 
      public int getSize() { return strings.length; } 
      public Object getElementAt(int i) { return strings[i]; } 
     }); 
     jList1.addListSelectionListener(new ListSelectionListener() { 
      public void valueChanged(ListSelectionEvent evt) { 
       jList1ValueChanged(evt); 
      } 
     }); 


     jTextField2.setText("jTextField1"); 
     jPanel1.add(jList1); 
     jPanel1.add(jTextField2); 
     frame.add(jPanel1); 
     frame.pack(); 
     frame.setVisible(true); 


    } 

    private void jList1ValueChanged(ListSelectionEvent evt) { 

    if(!jList1.getValueIsAdjusting()) 
    { 
    jTextField2.setText((String) jList1.getSelectedValue()); 
    } 
} 


    public static void main(String args[]) { 
     SwingUtilities.invokeLater(new Runnable() { 
      public void run() { 
       new JListTest(); 
      } 
     }); 
    } 
}