java - JProgressBar不会动态更新

Question

这个问题已经有答案了:

java jprogressbar hangs during heavy operation (2 个回答)

已关闭 8 年前。

我有一个 JFrame 类，里面有这个函数:

o=1;
private String performTest(int i,File file) throws IOException, InterruptedException {
        //CRAPPY CODE  
               while(o<=20) {
               Thread.sleep(1000); 
               progressBar.setValue((o/20)*100);              
               o++;
               }
        //CRAPPY CODE
    }

所以，进度条应该每秒更新一个更大的值，但我得到的只是 1 个最终更新(到 100)，当函数完成它的工作时；也许有一些方法可以解决这个问题？谢谢你的期待。 完整代码。

   btnTesteaz.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            int i = choice.getSelectedIndex();
            File file = fc.getSelectedFile();


            StringBuilder builder = new StringBuilder();        
            Thread t = new Thread(new Runnable() {
                @Override
                public void run() {

                        String name = Problems[i];
                        int o = 1;
                        try {

                        String pathToPas = file.getPath();
                        String pathToExe = pathToPas.replace(".pas", ".exe");
                        Process process = Runtime.getRuntime().exec("ppc386  "+pathToPas);
                        Thread.sleep(1000);
                        process.destroy();

                        while (new File("Res\\"+Problems[i]+"\\"+"Input"+o+".txt").exists()) { 
                            //FILES WITH INPUTS FROM RES
                            File in = new File("Res\\"+Problems[i]+"\\"+"Input"+o+".txt");
                            //FILES FOR .PAS
                            File inputtxt = new File(file.getParent()+"\\Input.txt");



                            BufferedReader bf = new BufferedReader(new FileReader(in));
                            PrintWriter w = new PrintWriter(new FileWriter(inputtxt));     
                            String s = null;
                            while ((s = bf.readLine())!=null)    {
                                w.println(s);
                            }
                            w.close();        
                            bf.close();
                            Process process1 = Runtime.getRuntime().exec(pathToExe,null, new File(file.getParent()));
                            Thread.sleep(1000);
                            process1.destroy();

                            File outputtxt = new File(file.getParent()+"\\Output.txt");
                            File out = new File("Res\\"+Problems[i]+"\\"+"Output"+o+".txt");
                            BufferedReader r1 = new BufferedReader(new FileReader(out)); 
                            BufferedReader r2 = new BufferedReader(new FileReader(outputtxt));                
                            StringBuilder ansRes = new StringBuilder();
                            StringBuilder ansPas = new StringBuilder();     
                                while ( (s=r1.readLine())!=null) ansRes.append(s);
                                while ( (s=r2.readLine())!=null) ansPas.append(s);

                            if (ansRes.toString().trim().equals(ansPas.toString().trim()))  {
                                builder.append("<p font color=green>"+(o)+". Test succesful </p> ") ;
                            }
                            else builder.append("<p font color=red>"+(o)+". Test failed </p>");
                            r1.close();
                            r2.close();

                               inputtxt.delete();
                               outputtxt.delete();

                               final int temp = o;
                               SwingUtilities.invokeLater(new Runnable() {
                                   public void run() {
                                       model.setValue((int) (((float) temp / 20.0f) * 100));
                                   }
                               });                               
                               o++;
                        }
                        File f = new File(pathToExe);
                        f.delete();
                        File fa = new File(file.getAbsolutePath().replace(".pas",".o"));
                        fa.delete();
                        }
                        catch (Exception e) {
                            e.printStackTrace();
                        }
                }
            });
            t.run();
        Result.setText(builder.toString());
        }
    });

Answer 1

这是 Swing 中的一个经典问题。 Swing 从其主线程进行所有图形更新，因此您不应该从那里执行长时间操作(您不会让它重新绘制!)

尝试将长时间操作转移到另一个线程，如本教程所示:

https://docs.oracle.com/javase/tutorial/uiswing/concurrency/worker.html

这将教您如何在后台执行长时间耗时的任务，同时实时更新 UI，而不会扰乱 Swing 架构