Question

我这里有一个进度条示例：

    import java.awt.BorderLayout;
    import java.awt.Container;

    import javax.swing.BorderFactory;
    import javax.swing.JFrame;
    import javax.swing.JProgressBar;
    import javax.swing.border.Border;

    public class ProgressSample {
      public static void main(String args[]) {
        JFrame f = new JFrame("JProgressBar Sample");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Container content = f.getContentPane();
        JProgressBar progressBar = new JProgressBar();
        progressBar.setValue(25);
        progressBar.setStringPainted(true);
        Border border = BorderFactory.createTitledBorder("Reading...");
        progressBar.setBorder(border);
        content.add(progressBar, BorderLayout.NORTH);
        f.setSize(300, 100);
        f.setVisible(true);
      }
    }

现在..有没有办法让值从0到100％运行而没有按钮触发它。就像我运行该帧一样，Thread或Timer会自动启动。有办法吗？或者我仍然需要一个按钮来触发计时器/线程？

Answer 1

简单的回答是，是的。

您可以随时更新进度条，只要您在事件调度线程的上下文中执行此操作即可。您需要的是告诉JProgressBar新值应该是什么的某种方式，但这取决于您要实现的目标。

import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JProgressBar;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class AutoProgress {

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

    private JProgressBar pb;
    private int progress;

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

                pb = new JProgressBar();

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new GridBagLayout());
                frame.add(pb);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);

                Timer timer = new Timer(50, new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        progress += 1;
                        if (progress >= 100) {
                            progress = 100;
                            ((Timer)e.getSource()).stop();
                        }
                        pb.setValue(progress);
                    }
                });
                timer.start();
            }
        });
    }

}

您可能还想查看JProgressBar#setIndeterminate。

您还应该查看How to use Swing Timers

在java中没有单击按钮的情况下自动启动进度条

1 个答案: