我的列表选择侦听器有一些问题，我将在下面展示给您1.监听器打印两次的结果，我都不知道…?? ?!为什么要打印两次?2.当我按下searchBt和结果显示，我选择的结果之一，我想从valueChanged(ListSelectionEvent e)返回ChooseIndex，但它不能有一个返回语句和这些j列表的选定索引是无用的…有什么问题吗?
public class SearchPage extends javax.swing.JFrame {
public SearchPage() {
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() {
SearchBox = new javax.swing.JTextField();
SearchBt = new javax.swing.JButton();
jScrollPane1 = new javax.swing.JScrollPane();
jList1 = new javax.swing.JList();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
SearchBt.setText("Search");
SearchBt.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
SearchBtActionPerformed(evt);
}
});
jList1.setSelectionMode(javax.swing.ListSelectionModel.SINGLE_INTERVAL_SELECTION);
jList1.setToolTipText("");
jList1.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
jList1.setSelectionBackground(new java.awt.Color(102, 0, 102));
jList1.setValueIsAdjusting(true);
jList1.setVerifyInputWhenFocusTarget(false);
jScrollPane1.setViewportView(jList1);
jList1.getAccessibleContext().setAccessibleName("");
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(16, 16, 16)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 543, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createSequentialGroup()
.addComponent(SearchBox, javax.swing.GroupLayout.PREFERRED_SIZE, 244, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(SearchBt, javax.swing.GroupLayout.PREFERRED_SIZE, 140, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addContainerGap(281, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(125, 125, 125)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(SearchBox, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(SearchBt))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 315, Short.MAX_VALUE)
.addContainerGap())
);
pack();
}// </editor-fold>
private void SearchBtActionPerformed(java.awt.event.ActionEvent evt) {
String tag = SearchBox.getText().trim();
Vector<String> vector = new Vector<String>();
for (int i = 0; i <Code.CodeSearch(tag).size(); i++) {
String string = Code.FNameExtractor(Code.CodeSearch(tag).get(i).getFileName())+" Uploaded By "+Code.CodeSearch(tag).get(i).getUserdetails().getUsername();
vector.add(string);
}
jList1 = new JList<String>(vector);
ListSelectionModel listSelectionModel = jList1.getSelectionModel();
listSelectionModel.addListSelectionListener(new SharedListSelectionHandler());
listSelectionModel.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
jScrollPane1.setViewportView(jList1);
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(SearchPage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(SearchPage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(SearchPage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(SearchPage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new SearchPage().setVisible(true);
}
});
}
class SharedListSelectionHandler implements ListSelectionListener {
public void valueChanged(ListSelectionEvent e) {
ListSelectionModel lsm = (ListSelectionModel)e.getSource();
int ChooseIndex =lsm.getMaxSelectionIndex();
System.out.println(ChooseIndex);
}
}
// Variables declaration - do not modify
private javax.swing.JTextField SearchBox;
private javax.swing.JButton SearchBt;
private javax.swing.JList jList1;
private javax.swing.JScrollPane jScrollPane1;
// End of variables declaration
}
选择监听器只告诉我们所选项的索引。这是正常的。列表并不关心内容。您必须在某个地方存储列表模型(法律，您实际显示的字符串列表)，并使用来自侦听器的索引值来查找模型中索引处的内容。这是常见的模式。
对于第一个问题-我将在print语句上设置一个断点，调试并查看堆栈跟踪。然后我就知道为什么这个方法被调用了两次。