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在家里，扩展了今年冬天的课堂作业，试图让它在运行时更新一个 GUI 元素，以显示他循环的进度。

预期的功能是，当它通过字符串时，处理每个字符，从 GUI 类传入的 JLable在每次循环迭代时更新以显示通过字符串的进度。但是，发生的情况是它只会在循环之后更改标签上显示的内容，在最终Thread.sleep (1000)过期之后（我不知道它是在合成器关闭之前还是之后，不要认为它会相关:/)。

在这一点上，我想就如何让 JLabel 的“进度”在循环到期之前更改为“应该显示”文本提出建议——一些与我的问题无关的代码已被删除以保护效率。

import javax.sound.midi.MidiSystem;
import javax.sound.midi.Synthesizer;
import javax.sound.midi.MidiChannel;
import javax.swing.JLabel;

public class SoundPlayer {

 /*Deceleration of private variables for the class*/

/*Constructor that assighns variables and triggers doPlay()method. 
There is a reference to the JLabel 'Progress' passed in and declared beforehand, 
 so there is access.*/
}

public void doPlay() {
    int totalSound;
    playNumTimes = 1;
    defaultTime = true;
    sound = 0;
    extraSound = 0;

    try {   //Opens ability to play the music.
        Synthesizer synth = MidiSystem.getSynthesizer();
        synth.open();       //Will likely play sound, so opens channel.
        MidiChannel[] channels = synth.getChannels();

        musicNotes += ".";  //illegal character will mark end of string to play.

        //Examines each char of the String and acts accordingly.
        for (count = 0; count < musicNotes.length(); count++) { //For each char in the input.

            if (processChar(musicNotes.charAt(count))) { //If processed char is illegal and triggers a sound, play it!
                totalSound = extraSound + sound;    //Combines from given note and the < and >s.


                progress.setText("Should show");

                //PLAYS SOUND HERE!
                channels[channel].noteOn(totalSound, volume);
                Thread.sleep(300 * playNumTimes);   //Plays sound a number times equal to times.
                channels[channel].noteOff(totalSound);

                //After plays, resets values.
                playNumTimes = 1;
                defaultTime = true;
                sound = 0;      //Sound of 0 used to indicate no char has been assigned to the sound.
            }
        }
        Thread.sleep(1000);     //Wards against synthesizer from being closed prematurely and cutting off sound.
        synth.close();  //Closes after loop is finished.
    }
    catch (Exception e){
        e.printStackTrace();
    }
}
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