i 有 jTextfield 和 jButton。
如何
- 用户可以单击jTextfield(鼠标可以在jtextfield上进入/退出),但是如果用户键入某些内容,则不会执行任何操作(除了将删除整个文本的退格键)
- 当用户单击按钮时,它将
jTextfield.setText("something");
因此,给 jtextfield 文本的唯一方法是单击按钮
- 当
- 那里有文本时(当光标在jtextfield内时),然后用户输入退格键,它将删除jtextfield上的整个文本。
怎么做?
原谅我的英语..非常感谢任何形式的帮助..
使用DocumentFilter
,只需将其添加到您的JTextField
中,如下所示:
public class Test {
public void initComponents() {
//create frame
//add DoucmentFilter to JTextField
MyDocumentFilter myFilter = new MyDocumentFilter();
JTextField myArea = new JTextField();
((AbstractDocument)myArea.getDocument()).setDocumentFilter(myFilter);
//add components set frame visible
}
}
class MyDocumentFilter extends DocumentFilter {
@Override
public void replace(FilterBypass fb, int i, int i1, String string, AttributeSet as) throws BadLocationException {
super.replace(fb, i, i1, string, as);
}
@Override
public void remove(FilterBypass fb, int i, int i1) throws BadLocationException {
super.remove(fb, i, i1);
}
@Override
public void insertString(FilterBypass fb, int i, String string, AttributeSet as) throws BadLocationException {
super.insertString(fb, i, string, as);
}
}
或者
您可能希望创建一个自定义 JTextField,该字段已经具有如下DocumentFilter
(用于可重用性):
public class MyCustomField extends JTextField {
public MyCustomField(int cols) {
super(cols);
}
protected Document createDefaultModel() {
return ((Document) new MyDocument());
}
static class MyDocument extends DocumentFilter {
@Override
public void insertString(FilterBypass fb, int i, String string, AttributeSet as) throws BadLocationException {
super.insertString(fb, i, string, as);
}
@Override
public void remove(FilterBypass fb, int i, int i1) throws BadLocationException {
super.remove(fb, i, i1);
}
@Override
public void replace(FilterBypass fb, int i, int i1, String string, AttributeSet as) throws BadLocationException {
super.replace(fb, i, i1, string, as);
}
}
}
从气垫船
编辑我沿着这些思路思考更多
import java.awt.event.ActionEvent;
import javax.swing.*;
import javax.swing.text.*;
public class Test {
public void initComponents() {
JPanel panel = new JPanel();
final MyDocumentFilter myFilter = new MyDocumentFilter();
final JTextField myArea = new JTextField(20);
((AbstractDocument) myArea.getDocument()).setDocumentFilter(myFilter);
panel.add(myArea);
panel.add(new JButton(new AbstractAction("Set Text") {
@Override
public void actionPerformed(ActionEvent arg0) {
myFilter.setFiltering(false);
myArea.setText("Fe Fi Fo Fum");
myFilter.setFiltering(true);
}
}));
JOptionPane.showMessageDialog(null, panel);
// add components set frame visible
}
public static void main(String[] args) {
new Test().initComponents();
}
}
class MyDocumentFilter extends DocumentFilter {
private boolean filtering = true;
@Override
public void replace(FilterBypass fb, int i, int i1, String string,
AttributeSet as) throws BadLocationException {
if (!filtering) {
super.replace(fb, i, i1, string, as);
}
}
@Override
public void remove(FilterBypass fb, int i, int i1)
throws BadLocationException {
int offset = 0;
int length = fb.getDocument().getLength();
super.remove(fb, offset, length);
}
@Override
public void insertString(FilterBypass fb, int i, String string,
AttributeSet as) throws BadLocationException {
if (!filtering) {
super.insertString(fb, i, string, as);
}
}
public void setFiltering(boolean filtering) {
this.filtering = filtering;
}
}
在 jText 字段的密钥侦听器中,在 keyTyped 事件中,检查 e.getKeyChar() 是否是退格键,如果不是,则执行 e.consume(); 它将取消事件
退格键的键字符为 8
下面是一个示例:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
public class ConsumeExceptForBackSpace extends JFrame {
private boolean canWrite = false;
public ConsumeExceptForBackSpace() {
super();
JButton b = new JButton("Click");
JTextField f = new JTextField("");
this.setLayout(new BorderLayout());
this.add(b, BorderLayout.CENTER);
this.add(f, BorderLayout.SOUTH);
b.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
canWrite = !canWrite;
}
});
f.addKeyListener(new KeyListener() {
@Override
public void keyTyped(KeyEvent e) {
if(e.getKeyChar() != KekEvent.VK_BACK_SPACE && !canWrite) e.consume();
}
@Override
public void keyReleased(KeyEvent e) {
}
@Override
public void keyPressed(KeyEvent e) {
}
});
this.pack();
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setVisible(true);
}
public static void main(String[] args) {
new ConsumeExceptForBackSpace();
}
}