java 更新jlabel_Java-更改JLabel

小编典典

可能是您更新了错误的字符串或设置了不正确的标签文本。两者都是必需的。在下面的示例(使用您的名称)中，两个更新在按钮的中紧密结合actionPerformed()。这里显示了一种更宽松的耦合方法。

import java.awt.EventQueue;

import java.awt.GridLayout;

import java.awt.event.ActionEvent;

import javax.swing.AbstractAction;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JPanel;

/** @see https://stackoverflow.com/questions/9053824 */

public class JavaGUI extends JPanel {

private Control control = new Control();

private Keys keys = new Keys("Original starting value.");

public JavaGUI() {

this.setLayout(new GridLayout(0, 1));

this.add(keys);

this.add(control);

}

private class Control extends JPanel {

public Control() {

this.add(new JButton(new AbstractAction("Update") {

@Override

public void actionPerformed(ActionEvent e) {

System.out.println("Command: " + e.getActionCommand());

keys.string = String.valueOf(System.nanoTime());

keys.label.setText(keys.string);

}

}));

}

}

private class Keys extends JPanel {

private String string;

private JLabel label = new JLabel();

public Keys(String s) {

this.string = s;

label.setText(s);

this.add(label);

}

}

private void display() {

JFrame f = new JFrame("JavaGUI");

f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

f.add(this);

f.pack();

f.setLocationRelativeTo(null);

f.setVisible(true);

}

public static void main(String[] args) {

EventQueue.invokeLater(new Runnable() {

@Override

public void run() {

new JavaGUI().display();

}

});

}

}

2020-12-03