java 按钮问题

Question

原来按钮是不可点击的，在文本框输入文本后，按钮变亮，可点击
就是一输入信息就变亮，不需要点任何键
要怎么实现
大神们帮帮忙

Answer 1

final doc = jtextfield.getDocument();
doc.addDocumentListener(new DocumentListener(){
    public void changedUpdate(DocumentEvent e){
        handler();
    }
    public void insertUpdate(DocumentEvent e){
        handler();
    }
    public void removeUpdate(DocumentEvent e){
        handler();
    }
    private void handler(){
         jbutton.setEnabled(doc.getLength() > 0);
    }
});

Answer 2

TextListener -> textValueChanged()方法

Answer 3

下载betterbeansbinding-1.3.0-all.jar
import org.jdesktop.beansbinding.BeanProperty;
import org.jdesktop.beansbinding.ELProperty;
import static org.jdesktop.beansbinding.Bindings.createAutoBinding;
import static org.jdesktop.beansbinding.AutoBinding.UpdateStrategy.READ;import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JButton;
import javax.swing.Box;public class Rocks {
    public static void main(final java.lang.String[] args) throws Exception {
        java.awt.EventQueue.invokeLater(new java.lang.Runnable(){
                @Override public void run(){
                    JFrame frame = new JFrame("Java Rocks");
                    JTextField input = new JTextField(10);
                    JButton button = new JButton("Click!");
                    button.setEnabled(false);
                    createAutoBinding(READ,
                                      input,ELProperty.create("${text != \"\"}"),
                                      button,BeanProperty.create("enabled")).bind();
                    Box container = Box.createHorizontalBox();
                    container.add(input);
                    container.add(button);
                    frame.add(container);
                    frame.pack();
                    frame.setLocationRelativeTo(null);
                    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                    frame.setVisible(true);
                }
            });
    }
}

Answer 4

找不到这个方法啊。。我用的是netbeans

Answer 5

TextListener 是 AWT 的文本组件使用的监听器