我有一个JButton，它应该从我的GUI中的JTable中删除选定的行。但是，出于某种原因，我用来执行此操作的ActionListener()中的代码似乎永远不会被调用...
private void addListeners(){
...
//removeBtn = new JButton("Remove");
removeBtn.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
System.out.println("Remove button clicked. Printed from actionListener. ");
removeRow(e);
}
});
removeRow()方法稍后在同一个类中定义：
public void removeRow(ActionEvent arg0){
System.out.println("'Remove' button pressed, Printed from 'removeRow()' method. ");
int selectedRow = jEntityFilterTable.getSelectedRow();
DefaultTableModel model = (DefaultTableModel)jEntityFilterTable.getModel();
model.removeRow(selectedRow);
System.out.println("Selected row should have been removed. Printed from 'removeRow()' method. ");
removeBtn使用以下行声明为类顶部的全局变量：
private JButton removeBtn = new JButton("Remove");
当我运行代码，并单击GUI上的“删除”按钮时，没有任何反应，我甚至看不到控制台中显示的调试...但我无法解决为什么 - 任何人都可以发现我做错了什么？为什么没有调用actionListener / removeRow（）方法？
编辑07/07/2014 @ 13:20
以下是课程相关部分的完整代码，如下所示：
public class JConfigurationPane extends JPanel implements UndoableEditListener, ChangeListener, ActionListener
{
...
private JButton addBtn = null;
private JButton saveBtn = null;
private JButton removeBtn = new JButton("Remove"); //null;
private JButton editBtn = null;
public boolean addBtnClicked = false;
public boolean saveBtnClicked = false;
public boolean removeBtnClicked = false;
public boolean editBtnClicked = false;
/**
* This method initializes
*
*/
public JConfigurationPane(ConfigurationDataModel dataModel)
{
super();
this.dataModel = dataModel;
initialize();
initialiseData();
addListeners();
}
public JConfigurationPane()
{
super();
initialize();
addListeners();
}
private void addListeners()
{
System.out.println("--- 'addListeners()' method has been called. ---");
jcbRxFilterExcludes.addChangeListener(this);
docRxAddress = jfRxAddress.getDocument();
docRxPort = jfRxPort.getDocument();
docRxExerciseID = jfRxExerciseID.getDocument();
docRxMaxPduSize = jfRxMaxPduSize.getDocument();
docRxAddress.addUndoableEditListener(this);
docRxPort.addUndoableEditListener(this);
docRxExerciseID.addUndoableEditListener(this);
docRxMaxPduSize.addUndoableEditListener(this);
addBtn.addActionListener(this);
/*Add action listeners for other buttons (07/07/2014 @ 08:35)
saveBtn.addActionListener(this);
removeBtn.addActionListener(this);
editBtn.addActionListener(this);
Causes an "Exception in thread 'main', java.lang.nullPointerException on:
'saveBtn.addActionListener(this);
'addListeners();' call in 'public JConfigurationPane()'
'JConfigurationPane panel = new JConfigurationPane()' call in 'main(String[] args)'
*/
//removeBtn = new JButton("Remove");
removeBtn.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
System.out.println("Remove button clicked. Printed from actionListener. ");
removeRow(e);
/* System.out.println("'Remove' button pressed. ");
int selectedRow = jEntityFilterTable.getSelectedRow();
DefaultTableModel model = (DefaultTableModel)jEntityFilterTable.getModel();
model.removeRow(selectedRow);
System.out.println("Selected row should have been removed. "); */
}
});
}
private void initialiseData()
{
...
}
/**
* This method initializes this
*
*/
private void initialize() {
...
/*Create filter buttons */
System.out.println("------------------JButtons BEING CREATED---------------------");
addBtn = new JButton("Add");
addBtn.setBounds(950, 135, 125, 25);
// addBtn.addActionListener(new ActionListener(){
// public void actionPerformed(ActionEvent e){
// }
// });
JButton saveBtn = new JButton("Save");
saveBtn.setBounds(1100, 135, 125, 25);
JButton removeBtn = new JButton("Remove");
removeBtn.setBounds(950, 200, 125, 25);
JButton editBtn = new JButton("Edit");
editBtn.setBounds(1100, 200, 125, 25);
System.out.println("------------------JButtons CREATED-------------------------");
...
/*Add filter buttons */
System.out.println("-------------------JButtons BEING ADDED TO GUI--------------------");
this.add(addBtn);
this.add(saveBtn);
this.add(removeBtn);
this.add(editBtn);
System.out.println("------------------JButtons ADDED TO GUI---------------------");
}
/**
* This method initializes jfRxAddress
*
* @return javax.swing.JTextField
*/
private JTextField getJfRxAddress()
{
...
}
/**
* This method initializes jfRxPort
*
* @return javax.swing.JTextField
*/
private JTextField getJfRxPort()
{
...
}
/**
* This method initializes jfRxExerciseID
*
* @return javax.swing.JTextField
*/
private JTextField getJfRxExerciseID()
{
...
}
/**
* This method initializes jEntityFilterPane
*
* @return javax.swing.JScrollPane
*/
private JScrollPane getJEntityFilterPane()
{
...
}
/**
* This method initializes jEntityFilterTable
*
* @return javax.swing.JTable
*/
private JTable getJEntityFilterTable()
{
...
}
/**
* This method initializes jEntitySymbolsPane
*
* @return javax.swing.JScrollPane
*/
private JScrollPane getJEntitySymbolsPane()
{
...
}
/**
* This method initializes jEntitySymbolsTable
*
* @return javax.swing.JTable
*/
private JTable getJEntitySymbolsTable()
{
...
}
/*Method to add buttons to 'Plugin Configuration' window */
private void addButtons(){
/*Buttons moved up to initialize() method on 25/06/2014 @ 17:00 */
JButton addBtn = new JButton("Add");
JButton saveBtn = new JButton("Save");
JButton removeBtn = new JButton("Remove");
JButton editBtn = new JButton("Edit");
addBtn.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
/*(25/06/2014 @ 15:20) Need to add code here to add a new editable row to 'Entity Filter' table */
addBtnClicked = true;
}
});
//addBtn.setBounds(1150, 135, 30, 15);
saveBtn.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
/*(25/06/2014 @ 15:20) Need to add code here to save the data in the 'Entity Filter' table to a set of variables */
saveBtnClicked = true;
}
});
//saveBtn.setBounds(1190, 135, 30, 15);
removeBtn.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
/*(25/05/2014 @ 15:25) Need to add code here to remove the data in selected row from variables, and remove row from table */
removeBtnClicked = true;
}
});
//removeBtn.setBounds(1150, 160, 30, 15);
editBtn.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
/*(25/06/2014 @ 15:25) Need to add code here to enable editing of data in selected row */
editBtnClicked = true;
}
});
//editBtn.setBounds(1190, 160, 30, 15);
System.out.println("'addButtons()' method is being called by 'initialize()' in JConfigurationPanel.java");
}
/**
* This method initializes jcbRxFilterExcludes
*
* @return javax.swing.JCheckBox
*/
private JCheckBox getJcbRxFilterExcludes()
{
...
}
/**
* This method initializes jfRxMaxPduSize
*
* @return javax.swing.JTextField
*/
private JTextField getJfRxMaxPduSize()
{
...
}
@Override
public void undoableEditHappened(UndoableEditEvent editEvent)
{
...
}
@Override
public void stateChanged(ChangeEvent changeEvent)
{
...
}
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setMinimumSize(new Dimension(500,500));
frame.setSize(new Dimension(500,500));
JConfigurationPane panel = new JConfigurationPane();
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
@Override
public void actionPerformed(ActionEvent arg0) {
/*Check which button has been pressed, perform a different action depending on which button it was. Reset the check variables
* to false after performing action */
// TODO Auto-generated method stub
/*Code to add row to table when button is pressed */
System.out.println("'Add' button pressed.");
DefaultTableModel model = (DefaultTableModel)jEntityFilterTable.getModel();
Object[] obj = new Object[]{};
System.out.println("Row Count: " + model.getRowCount());
System.out.println("1st Column: " + model.getColumnName(0));
System.out.println("Column Count: " + model.getColumnCount());
model.addRow(obj);
System.out.println("--- ActionListener added to 'addBtn' ---");
/*Code to remove selected row from the table when button is clicked
int selectedRow = jEntityFilterTable.getSelectedRow();
model.removeRow(selectedRow); */
}
public void removeRow(ActionEvent arg0){
System.out.println("'Remove' button pressed. Printed from 'removeRow()' method. ");
int selectedRow = jEntityFilterTable.getSelectedRow();
DefaultTableModel model = (DefaultTableModel)jEntityFilterTable.getModel();
model.removeRow(selectedRow);
System.out.println("Selected row should have been removed. Printed from 'removeRow()' method. ");
}
}
答案 0 :(得分：1)
在initialize()方法中，您要添加到面板的removeBtn是该方法的局部变量。 addButtons()方法中也出现同样的情况。然后，稍后，当您致电addListeners()时，您将ActionListener添加到未添加到面板的私人会员JButton。从JButton removeBtn方法中删除本地initialize()，然后初始化成员。
答案 1 :(得分：0)
尝试将按钮声明为最终字段。如果代码的某些部分更改了按钮对象，则会收到警告。
答案 2 :(得分：0)
再次出现空指针异常。
在您的代码中使用：
JConfigurationPane panel = new JConfigurationPane();
而不是：
public JConfigurationPane(ConfigurationDataModel dataModel)
为什么你有两个构造者？为什么要将数据模型传递给类？
另外，请勿使用setBounds（）来设置按钮的大小/位置。 Swing旨在与布局管理器一起使用，因此使用布局管理器。也许你会从使用FlowLayout的小组开始。
最后，以下代码（可能）不起作用：
model.removeRow(selectedRow);
所选行指的是表视图中的行，而不是表模型中的行。如果您的代码进行排序或过滤，那么索引可能会有所不同。首先需要使用以下方法转换所选索引：
JTable.convertRowIndexToModel(...);