在SwingWorker線程內更新JLabel的行為不正常

Question

我試圖更新JLabel的一些預期行為，如 -

COND 1：JLabel應該顯示5秒鍾，然后它應該在接下來的3秒內不可見，然后它應該可見5秒鍾，依此類推。

COND 2：JLabel應該顯示0.5秒，然后對於接下來的3個secons應該是不可見的。

任何排列組合的種類，行為應該有效。 以下是示例代碼 -

import java.awt.LayoutManager;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.List;

import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingWorker;

public class Main
{
    static CounterTask task;

    public static void main ( String[] args )
    {

        final JLabel label = new JLabel( "TEST ME " );
        JButton startButton = new JButton( "Start" );
        startButton.addActionListener( new ActionListener()
        {
            public void actionPerformed ( ActionEvent e )
            {
                task = new CounterTask( label );
                task.execute();
            }
        } );

        JButton cancelButton = new JButton( "Cancel" );
        cancelButton.addActionListener( new ActionListener()
        {
            public void actionPerformed ( ActionEvent e )
            {
                task.cancel( true );
            }
        } );

        JPanel buttonPanel = new JPanel();
        buttonPanel.add( startButton );
        buttonPanel.add( cancelButton );

        JPanel cp = new JPanel();
        LayoutManager layout = new BoxLayout( cp, BoxLayout.Y_AXIS );
        cp.setLayout( layout );
        cp.add( buttonPanel );
        cp.add( label );

        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        frame.setContentPane( cp );
        frame.pack();
        frame.setVisible( true );
    }
}

class CounterTask
    extends SwingWorker< Integer, Integer >
{
    int DELAY = 3000;

    JLabel label;

    int WAIT = 5000;

    public CounterTask ( JLabel label )
    {
        this.label = label;
    }

    @Override
    protected Integer doInBackground () throws Exception
    {
        int i = 0;
        int count = 1000;
        while ( !isCancelled() && i < count )
        {
            i++;
            publish( new Integer[] { i } );
            label.setVisible( false );
            Thread.sleep( DELAY );
        }
        return count;
    }

    protected void process ( List< Integer > chunks )
    {
        Integer strContent = chunks.get( chunks.size() - 1 );
        label.setVisible( true );
        label.validate();
        label.setText( "DISPLAYING " + strContent );
        try
        {
            Thread.sleep( WAIT );
        }
        catch ( InterruptedException e )
        {
            e.printStackTrace();
        }
    }

    @Override
    protected void done ()
    {
        if ( isCancelled() )
            System.out.println( "Cancelled !" );
        else
            System.out.println( "Done !" );
    }
}

我肯定做錯了，因為這種組合適用於某些數據，並且大多數JLabel在整個過程中變得不可見，但是如果我放置SOP，我會在適當的延遲和等待時間獲得適當的數據。

上面的Swing worker代碼有兩個變量WAIT，DELAY。 WAIT使JLabel可見X秒，DELAY使JLAbel在Y秒內不可見。 但如果嘗試不同的燙發和梳理，你會發現JLabel的可見性不能按預期工作。 這可能是因為標簽的EDT更新或與重繪有關的事情。 不確定根本原因。

預期：

1. 想要使代碼像SOP一樣工作或理想情況下工作。
2. 需要知道不正常行為的原因。

Answer 1

SwingWorker只是一個閃爍的標簽是一種矯枉過正。 嘗試以下基於計時器的方法，它根本不需要線程魔術：

public class Main {
private static Timer setVisibleTimer;
private static Timer setInvisibleTimer;

public static void main(String[] args) {

    final JLabel label = new JLabel("TEST ME ");
    JButton startButton = new JButton("Start");
    startButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            setVisibleTimer = new Timer(8000, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    label.setVisible(true);
                }
            });
            setInvisibleTimer = new Timer(5000, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    label.setVisible(false);
                }
            });
            setVisibleTimer.start();
            setInvisibleTimer.start();
        }
    });

    JButton cancelButton = new JButton("Cancel");
    cancelButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            label.setVisible(true);
            if (setVisibleTimer != null){
                setInvisibleTimer.stop();
                setVisibleTimer.stop();
            }
        }
    });

    JPanel buttonPanel = new JPanel();
    buttonPanel.add(startButton);
    buttonPanel.add(cancelButton);

    JPanel cp = new JPanel();
    LayoutManager layout = new BoxLayout(cp, BoxLayout.Y_AXIS);
    cp.setLayout(layout);
    cp.add(buttonPanel);
    cp.add(label);

    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setContentPane(cp);
    frame.pack();
    frame.setVisible(true);
}
}

Answer 2

不，你永遠不會在EDT上等待：而是將所有邏輯放入doInBackground，並發布標簽狀態

用一些代碼充實我的評論（可以在Timer中完成，但實際上我喜歡工人:)

static class LabelState {
    int count;
    boolean visible;

    public LabelState(boolean visible, int count) {
        this.count = count;
        this.visible = visible;
    }
}
static class CounterTask extends SwingWorker<Void, LabelState> {
    int DELAY = 3000;

    JLabel label;

    int WAIT = 5000;

    public CounterTask(JLabel label) {
        this.label = label;
    }

    @Override
    protected Void doInBackground() throws Exception {
        int i = 0;
        int count = 1000;
        while (!isCancelled() && i < count) {
            i++;
            publish(new LabelState(false, i));
            Thread.sleep(DELAY);
            i++;
            publish(new LabelState(true, i));
            Thread.sleep(WAIT);
        }
        return null;
    }

    protected void process(List<LabelState> chunks) {
        LabelState strContent = chunks.get(chunks.size() - 1);
        label.setVisible(strContent.visible);
        label.validate();
        label.setText("DISPLAYING " + strContent.count);
    }

    @Override
    protected void done() {
        if (isCancelled())
            System.out.println("Cancelled !");
        else
            System.out.println("Done !");
    }
}