您可以使用DocumentFilter来限制最大大小,请参阅本文档部分,其中提供了您需要的有效示例。
以这个为例,我使用了上面示例文件中的组件:
import java.awt.BorderLayout;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
import components.DocumentSizeFilter;
public class Test {
public static void main(String[] args) {
new TestFrame().setVisible(true);
}
private static class TestFrame extends JFrame{
private JTextField textField;
private DefaultStyledDocument doc;
private JLabel remaningLabel = new JLabel();
public TestFrame() {
setLayout(new BorderLayout());
textField = new JTextField();
doc = new DefaultStyledDocument();
doc.setDocumentFilter(new DocumentSizeFilter(500));
doc.addDocumentListener(new DocumentListener(){
@Override
public void changedUpdate(DocumentEvent e) { updateCount();}
@Override
public void insertUpdate(DocumentEvent e) { updateCount();}
@Override
public void removeUpdate(DocumentEvent e) { updateCount();}
});
textField.setDocument(doc);
updateCount();
add(textField, BorderLayout.CENTER);
add(remaningLabel, BorderLayout.soUTH);
setLocationRelativeTo(null);
pack();
}
private void updateCount()
{
remaningLabel.setText((500 -doc.getLength()) + " characters remaining");
}
}
}