Question

每次点击“加载”时，我都会尝试更新空的Jlabel。 JButton的。我已经向Jbutton添加了一个actionlistener，但由于某种原因，标签不会更新或使用setText（String）方法显示任何文本。

JLabel stupidLabel = new JLabel();
    stupidLabel.setForeground(SystemColor.infoText);
    stupidLabel.setFont(new Font("Arial", Font.PLAIN, 11));
    stupidLabel.setBounds(71, 46, 167, 14);
    panel.add(stupidLabel);'

JButton load = new JButton("Load");
    load.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {

           stupidLabel.setText("Update please");
        }
    });
    load.setFont(new Font("Arial", Font.PLAIN, 11));
    load.setBounds(189, 92, 89, 22);
    contentPane.add(load);

似乎没有效果。

似乎有什么问题？有没有办法让标签每隔一秒左右自动更新一次，有效地完全不需要按钮？

Answer 1

对我来说很好......

import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.SystemColor;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            JLabel stupidLabel = new JLabel(" ");
            stupidLabel.setForeground(SystemColor.infoText);
            stupidLabel.setFont(new Font("Arial", Font.PLAIN, 11));
            add(stupidLabel, gbc);

            JButton load = new JButton("Load");
            load.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {

                    stupidLabel.setText("Update please");
                }
            });
            load.setFont(new Font("Arial", Font.PLAIN, 11));
            add(load, gbc);
        }

    }

}

考虑提供展示您问题的runnable example。这不是代码转储，而是您正在做的事情的一个示例，它突出了您遇到的问题。这将减少混淆和更好的响应

Jlabel不会使用ActionListener中的setText进行更新？

1 个答案: