如何將元素動態添加到JList/DefaultListModel

Question

我想動態添加元素到我的DefaultListModel/JList，但該列表需要先清空。我打開一個對話窗口。我的問題是，當我使用model.removeAllElements()時，我的對話框窗口再次出現多次。我究竟做錯了什麼？

我也試過model.addElementAt(index)繞過model.removeAllElements()但結果是一樣的。

private javax.swing.JList serviceList; 
serviceList.setModel(model); 
serviceList.setSelectionMode(javax.swing.ListSelectionModel.SINGLE_SELECTION); 
serviceList.setLayoutOrientation(javax.swing.JList.HORIZONTAL_WRAP); 
serviceList.setSelectionBackground(java.awt.Color.white); 
serviceList.setVisibleRowCount(3); 
serviceList.addListSelectionListener(new javax.swing.event.ListSelectionListener() { 
     public void valueChanged(javax.swing.event.ListSelectionEvent evt) { 
      serviceListValueChanged(evt); 
     } 
    }); 

private void serviceListValueChanged(javax.swing.event.ListSelectionEvent evt) {           
    showTasksDialog(); 
} 

showTasksDialog()：當用戶點擊它連接到一個URL，然後將名單由filllst()更新的第一個打開一個對話框窗口的三個鍵。

public void showTasksDialog() { 
    int selection = serviceList.getSelectedIndex(); 
    Object[] options = {"Analyse", "Build", "Stop"}; 
    int n = taskDialog.showOptionDialog(this, 
      "What should this Service do?", 
      "", 
      JOptionPane.YES_NO_CANCEL_OPTION, 
      JOptionPane.QUESTION_MESSAGE, 
      null, 
      options, 
      null); 
    if (n == 0) { 
     try { 
      connection.setSlaveToAnalyse(serviceURLJSONArray.getString(selection)); 
      filllist(); 
     } catch (JSONException | IOException ex) { 
      Logger.getLogger(GUI.class.getName()).log(Level.SEVERE, null, ex); 
     } 
    } 
} 

filllist()：應該從我的默認列表和填充它刪除所有的元素，但如果我用model.removeAllElements()對話框窗口再次出現多次。當我不使用removeAllElements那麼一切都很好，但名單還沒有被清空

public void filllist() throws JSONException, IOException {   
    model.removeAllElements(); 
    serviceURLJSONArray = connection.getSlaves(); 
    for (int i = 0; i < serviceURLJSONArray.length(); i++) { 
     String slaveStatus = new Connection().getSlaveStatus(serviceURLJSONArray.getString(i)); 
     model.addElement("Service " +(i+1)+" "+slaveStatus); 
    } 
} 

Answer 1

刪除監聽器（或禁用它們）刪除和添加元素之前從列表中，然後在完成時重新添加該監聽器。

例如，

public void filllist() throws JSONException, IOException {   

    // remove all listeners 
    ListSelectionListener[] listeners = serviceList.getListSelectionListeners(); 
    for (ListSelectionListener l : listeners) { 
     serviceList.removeListSelectionListener(l); 
    } 

    // do your work 
    model.removeAllElements(); 
    serviceURLJSONArray = connection.getSlaves(); 
    for (int i = 0; i < serviceURLJSONArray.length(); i++) { 
     String slaveStatus = new Connection().getSlaveStatus(serviceURLJSONArray.getString(i)); 
     model.addElement("Service " +(i+1)+" "+slaveStatus); 
    } 

    // add them back 
    for (ListSelectionListener l : listeners) { 
     serviceList.addListSelectionListener(l); 
    } 

}