Question

我只想数点jlabel。我想，我已经尝试了网站上发布的所有解决方案，但我找不到任何解决方案。我是初学者，有一个月的时间学习Java。如果我的问题太愚蠢，我很抱歉。

package asdf;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.JLabel;

public class asd extends JFrame implements ActionListener {
int a=0;  // variable
private JFrame frame;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                asd window = new asd();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the application.
 */
public asd() {
    super();
    Timer time=new Timer(1000, this); 
    time.start(); 
    initialize();
}

/**
 * Initialize the contents of the frame.
 */
private void initialize() {

    frame = new JFrame();
    frame.setBounds(100, 100, 450, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().setLayout(null);

    JPanel panel = new JPanel();
    panel.setBounds(20, 11, 137, 111);
    frame.getContentPane().add(panel);
    panel.setLayout(null);

    ***JLabel Jtable = new JLabel();
    Jtable.setBounds(0, 25, 127, 58);
    Jtable.setText("" + a);
    panel.add(Jtable);***

    System.out.println(a); //it is counting on console but in Jlabel variable is not.

}

@Override
public void actionPerformed(ActionEvent arg0) {
    a++;
    initialize();   
}
}

我只想数点jlabel。我想，我已经尝试了网站上发布的所有解决方案，但我找不到任何解决方案。我是初学者，有一个月的时间学习Java。如果我的问题太愚蠢，我很抱歉。

Answer 1

您不应该在执行的每个操作上初始化新框架和所有组件，您应该只更新标签的文本。您可以通过JLabel.setText https://docs.oracle.com/javase/7/docs/api/javax/swing/JLabel.html#setText(java.lang.String)

执行此操作

int a = 0;  // variable
private JFrame frame;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                asd window = new asd();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the application.
 */
public asd() {
    super();
    Timer time=new Timer(1000, this); 
    time.start(); 
    initialize();
}

/**
 * Initialize the contents of the frame.
 */

private JLabel label;
private void initialize() {

    frame = new JFrame();
    frame.setBounds(100, 100, 450, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().setLayout(null);

    JPanel panel = new JPanel();
    panel.setBounds(20, 11, 137, 111);
    frame.getContentPane().add(panel);
    panel.setLayout(null);

    label = new JLabel();
    label.setBounds(0, 25, 127, 58);
    label.setText("" + a);
    panel.add(label);

    System.out.println(a); //it is counting on console but in Jlabel variable is not.

}

@Override
public void actionPerformed(ActionEvent arg0) {
    a++;

    label.setText("" + a);

}

为什么我无法在JLabel中更改变量？

1 个答案: