JProgressBar 在 Try-catch 完成之前不会启动

Question

我正在编写一个使用 Random.ORG api 的程序。当我单击计算按钮时，JProgressBar 在操作完成后立即启动并保持冻结状态直到这一刻。

我尝试了额外的 try-catch 子句、if 语句和布尔门。 None 成功了，我该如何解决？

kazananiBelirleButon.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {

                progressBar.setVisible(true);
                progressBar.setIndeterminate(true);

                try {

                    HashMap<String, Object> randoms = randSonuc.generateSignedIntegers(5, 0, 10);
                    System.out.println(randoms.toString());
                    String test = randoms.toString().substring(randoms.toString().indexOf("{r")+1, randoms.toString().indexOf(", da")).replace("random=", "{\"random\":") + "}";


                    System.out.println(tarihiYazdir(test,14));
                    cekilisTarihiTextPane.setText(tarihiYazdir(test,2).toString());
                    sonucPane.setText("\n"+sonuclariYazdir(test,0));



                } catch (RandomOrgSendTimeoutException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                } catch (RandomOrgKeyNotRunningError e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                } catch (RandomOrgInsufficientRequestsError e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                } catch (RandomOrgInsufficientBitsError e1) {
                    System.out.print("lol");
                    e1.printStackTrace();
                } catch (RandomOrgBadHTTPResponseException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                } catch (RandomOrgRANDOMORGError e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                } catch (RandomOrgJSONRPCError e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                } catch (MalformedURLException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                } catch (IOException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }
            }
        });

Answer 1

Swing 是单线程的。调用侦听器，painting/updating UI 都发生在称为 Event Dispatch Thread (EDT) 的单个线程上。

由于您在事件处理程序代码中完成了所有工作，Swing UI 无法更新，直到您从您的方法 (actionPerformed()) return。

阅读本教程：Concurrency in Swing

您应该做的是在单独的线程中完成耗时的工作，并且只在 EDT 中执行短任务（例如 UI 更新）。

另请查看 SwingWorker class，它旨在在后台线程中执行冗长的 GUI 交互任务。

Answer 2

尝试在您的方法中使用 swing worker。 Swing Worker

这里是旧版 swing worker 的例子。首先，您需要将 SwingWorker class 添加到您的项目中：

import javax.swing.SwingUtilities;

/**
 * This is the 3rd version of SwingWorker (also known as
 * SwingWorker 3), an abstract class that you subclass to
 * perform GUI-related work in a dedicated thread.  For
 * instructions on using this class, see:
 *
 * http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html
 *
 * Note that the API changed slightly in the 3rd version:
 * You must now invoke start() on the SwingWorker after
 * creating it.
 */
public abstract class SwingWorker
{

    private Object value;  // see getValue(), setValue()
    private Thread thread;

    /**
     * Class to maintain reference to current worker thread
     * under separate synchronization control.
     */
    private static class ThreadVar
    {

        private Thread thread;

        ThreadVar(Thread t)
        {
            thread = t;
        }

        synchronized Thread get()
        {
            return thread;
        }

        synchronized void clear()
        {
            thread = null;
        }
    }
    private ThreadVar threadVar;

    /**
     * Get the value produced by the worker thread, or null if it
     * hasn't been constructed yet.
     */
    protected synchronized Object getValue()
    {
        return value;
    }

    /**
     * Set the value produced by worker thread
     */
    private synchronized void setValue(Object x)
    {
        value = x;
    }

    /**
     * Compute the value to be returned by the <code>get</code> method.
     */
    public abstract Object construct();

    /**
     * Called on the event dispatching thread (not on the worker thread)
     * after the <code>construct</code> method has returned.
     */
    public void finished()
    {
    }

    /**
     * A new method that interrupts the worker thread.  Call this method
     * to force the worker to stop what it's doing.
     */
    public void interrupt()
    {
        Thread t = threadVar.get();
        if (t != null)
        {
            t.interrupt();
        }
        threadVar.clear();
    }

    /**
     * Return the value created by the <code>construct</code> method.
     * Returns null if either the constructing thread or the current
     * thread was interrupted before a value was produced.
     *
     * @return the value created by the <code>construct</code> method
     */
    public Object get()
    {
        while (true)
        {
            Thread t = threadVar.get();
            if (t == null)
            {
                return getValue();
            }
            try
            {
                t.join();
            }
            catch (InterruptedException e)
            {
                Thread.currentThread().interrupt(); // propagate
                return null;
            }
        }
    }

    /**
     * Start a thread that will call the <code>construct</code> method
     * and then exit.
     */
    public SwingWorker()
    {
        final Runnable doFinished = new Runnable()
        {

            public void run()
            {
                finished();
            }
        };

        Runnable doConstruct = new Runnable()
        {

            public void run()
            {
                try
                {
                    setValue(construct());
                }
                finally
                {
                    threadVar.clear();
                }

                SwingUtilities.invokeLater(doFinished);
            }
        };

        Thread t = new Thread(doConstruct);
        threadVar = new ThreadVar(t);
    }

    /**
     * Start the worker thread.
     */
    public void start()
    {
        Thread t = threadVar.get();
        if (t != null)
        {
            t.start();
        }
    }
}

然后在里面添加你的逻辑：

SwingWorker worker = new SwingWorker() {
    @Override
    public Object construct() {
        // add your code here
        progressBar.setVisible(true);
        progressBar.setIndeterminate(true);
        // and so on...

        return 0;
    }
};
worker.start();

所以最终结果应该是这样的（注意这是未经测试的代码）：

kazananiBelirleButon.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {

                SwingWorker worker = new SwingWorker() {

                    @Override
                    public Object construct() {
                        progressBar.setVisible(true);
                        progressBar.setIndeterminate(true);

                        try {

                            HashMap<String, Object> randoms = randSonuc.generateSignedIntegers(5, 0, 10);
                            System.out.println(randoms.toString());
                            String test = randoms.toString().substring(randoms.toString().indexOf("{r")+1, randoms.toString().indexOf(", da")).replace("random=", "{\"random\":") + "}";

                            System.out.println(tarihiYazdir(test,14));
                            cekilisTarihiTextPane.setText(tarihiYazdir(test,2).toString());
                            sonucPane.setText("\n"+sonuclariYazdir(test,0));

                        } catch (RandomOrgSendTimeoutException e1) {
                            // TODO Auto-generated catch block
                            e1.printStackTrace();
                        } catch (RandomOrgKeyNotRunningError e1) {
                            // TODO Auto-generated catch block
                            e1.printStackTrace();
                        } catch (RandomOrgInsufficientRequestsError e1) {
                            // TODO Auto-generated catch block
                            e1.printStackTrace();
                        } catch (RandomOrgInsufficientBitsError e1) {
                            System.out.print("lol");
                            e1.printStackTrace();
                        } catch (RandomOrgBadHTTPResponseException e1) {
                            // TODO Auto-generated catch block
                            e1.printStackTrace();
                        } catch (RandomOrgRANDOMORGError e1) {
                            // TODO Auto-generated catch block
                            e1.printStackTrace();
                        } catch (RandomOrgJSONRPCError e1) {
                            // TODO Auto-generated catch block
                            e1.printStackTrace();
                        } catch (MalformedURLException e1) {
                            // TODO Auto-generated catch block
                            e1.printStackTrace();
                        } catch (IOException e1) {
                            // TODO Auto-generated catch block
                            e1.printStackTrace();
                        }
                    }
                     return 0;
                }
            };
            worker.start();
        });

JProgressBar 在 Try-catch 完成之前不会启动

JProgressBar Doesn't Start Until Try-catch finishes

java

api

try-catch

jprogressbar

gson