当我单击一个表格单元格,然后单击第二个表格单元格时,发生许多我不理解的鼠标和焦点事件。例如,单击单元格(1、0),然后单击单元格(2、1),然后单击“完成”按钮以显示事件序列,将导致以下事件:
1)鼠标压在单元格上(1,0)
2)聚焦于单元格(1,0)
3)鼠标压在单元格(1,0)上-为什么(?)
4)鼠标压在单元格(2,1)上
5)专注于单元格(1,0)-为什么(?)
6)专注于单元格(2,1)
7)焦点集中在单元格(1,0)上-为什么(?)
8)聚焦于单元格(2,1)-为什么(?)
9)专注于单元格(1,0)-为什么(?)
10)焦点丢失在单元格(2,1)上-为什么(?)
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import javax.swing.*;
import static javax.swing.SwingConstants.CENTER;
import static javax.swing.SwingConstants.LEFT;
import javax.swing.SwingUtilities;
import javax.swing.table.*;
public class TestFocus {
public ArrayList<String> mylog;
public int number = 0;
public TestFocus() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = createPanel();
frame.add(panel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public JPanel createPanel() {
mylog = new ArrayList<>();
JPanel panel = new JPanel();
TestTableModel tm = new TestTableModel();
JLabel title = new JLabel("Test Table");
JTable table = new JTable(tm);
TableColumnModel tcm = table.getColumnModel();
TestTableCellEditor editor = new TestTableCellEditor();
TestTableCellRenderer renderer = new TestTableCellRenderer();
for (int i = 0; i < tm.getColumnCount(); i++) {
TableColumn column = tcm.getColumn(i);
column.setCellEditor(editor);
column.setCellRenderer(renderer);
}
JScrollPane jsp = new JScrollPane(table);
JButton btn = new JButton("Done");
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent ae) {
for (String s : mylog) {
System.out.println(s);
}
}
});
panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
panel.add(jsp);
panel.add(btn);
return panel;
}
class TestTableModel extends AbstractTableModel {
private String[] columnNames = { "Firstname", "Lastname", "Age" };
private Object[][] data = {
{ "John", "Smith", 29},
{ "Mary", "Thomas", 63},
{ "Peter", "Jones", 48} };
public int getColumnCount() {
return columnNames.length;
}
public int getRowCount() {
return data.length;
}
public String getColumnName(int col) {
return columnNames[col];
}
public Object getValueAt(int row, int col) {
return data[row][col];
}
public Class getColumnClass(int col) {
return getValueAt(0, col).getClass();
}
public String getColumnClassName(int col) {
if (col == 2) {
return "Integer";
} else {
return "String";
}
}
public boolean isCellEditable(int row, int col) {
return true;
}
public void setValueAt(Object value, int row, int col) {
data[row][col] = value;
fireTableCellUpdated(row, col);
}
}
public class TestTableCellEditor extends AbstractCellEditor
implements TableCellEditor {
JComponent component = new JTextField();
@Override
public Component getTableCellEditorComponent(JTable table, Object value,
boolean isSelected, int row, int column) {
((JTextField)component).addMouseListener(new MouseAdapter() {
@Override
public void mousePressed(MouseEvent me) {
mylog.add(++number + ") Mouse pressed: " +
value.toString() + ": r/c ("+row+"/"+column+")");
}
});
((JTextField)component).addFocusListener(new FocusListener() {
@Override
public void focusGained(FocusEvent fe) {
mylog.add(++number + ") Focus gained: " +
value.toString() + ": r/c ("+row+"/"+column+")");
}
@Override
public void focusLost(FocusEvent fe) {
mylog.add(++number + ") FocusLost: " +
value.toString() + ": r/c ("+row+"/"+column+")");
}
});
if (value != null) {
((JTextField)component).setText(value.toString());
} else {
((JTextField)component).setText("");
}
return (JTextField)component;
}
@Override
public Object getCellEditorValue() {
return ((JTextField)component).getText();
}
}
public class TestTableCellRenderer extends JLabel implements
TableCellRenderer {
public TestTableCellRenderer() {
this.setOpaque(true);
}
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, final int row, int column) {
DefaultTableCellRenderer renderer = new DefaultTableCellRenderer();
Component c = renderer.getTableCellRendererComponent(table, value,
isSelected, hasFocus, row, column);
if (hasFocus) {
c.setBackground(Color.yellow);
}
TestTableModel tm = (TestTableModel)table.getModel();
int col = table.convertColumnIndexToModel(column);
String colname = tm.getColumnName(col);
String type = tm.getColumnClassName(col);
if (type.equals("Integer") || type.equals("Int")) {
((JLabel)c).setHorizontalAlignment(CENTER);
} else { // add padding
((JLabel)c).setBorder(BorderFactory.createEmptyBorder(0, 10, 0, 10));
((JLabel)c).setHorizontalAlignment(LEFT);
}
if (type.equals("String")) {
String text = ((JLabel)c).getText();
((JLabel)c).setToolTipText(text);
}
return c;
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new TestFocus();
}
});
}
}
最佳答案
getTableCellEditorComponent
方法将在JTable
呈现时被调用-很多次。在其中textfield.addMouseListener()
。这意味着侦听器将被添加很多次。这就是为什么您收到许多事件而不是一个事件的原因(所有这些侦听器都会得到通知)。为了解决它,只添加一次监听器。您可以在此类的构造函数中添加侦听器。
例如:
public class TestTableCellEditor extends AbstractCellEditor implements TableCellEditor {
private JTextField component;
public TestTableCellEditor() {
component = new JTextField();
component.addMouseListener(mouseListener);
component.addFocusListener(focusListener)
}
@Override
public Object getCellEditorValue() {
return component.getText();
}
@Override
public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected, int row, int column) {
component.setText(value == null ? "" : String.valueOf(value));
return component;
}
}