Eclipse 中的 Java 错误 - soundresource 无法解析为变量

Question

我正在尝试将音乐文件导入到我的程序中，但也允许它在启动时在其中两个文件之间随机选择。我使用 URL 系统进行导入，因此我有一个名为 soundResource 的变量来完成此任务。

但是，每当我尝试运行它(使用 Eclipse，尽管我不认为这会导致错误)时，程序都会失败，并指出

soundResource cannot be resolved to a variable

我在其他主题中看到与此无关的内容，特别是它与变量的范围有关。如何修复下面的代码以使变量能够相互看到？

适用代码:

package Tetris;

//import java.io.InputStream;

import java.net.URL;
import java.util.Random;
import javax.sound.sampled.*;

public class Audio {
    Random rand = new Random(); 
    Boolean RandomSongNum = rand.nextBoolean();
    AudioInputStream ais;
    Clip clip;

    public Audio () {};

    public void playAudio () throws Exception {
        //open the sound file as a Java input stream
        //The Starter music file
        if(RandomSongNum){
            URL soundResource = this.getClass().getClassLoader().getResource("BH-Lightest.wav");
        } else {
            URL soundResource = this.getClass().getClassLoader().getResource("RY-Lightest.wav");
        }

        //Set audio path to within java file
        AudioInputStream in = AudioSystem.getAudioInputStream(soundResource); <<<--- Error occurs here

        clip = AudioSystem.getClip();

        clip.open(in);
        clip.loop(Clip.LOOP_CONTINUOUSLY);  //get the file to loop continuously 

    }

    public void playAudioMed () throws Exception {
        //open the sound file as a Java input stream
        //Medium score music file
        if (RandomSongNum) {
            URL soundResource = this.getClass().getClassLoader().getResource("BH-Light.wav");
        } else {
            URL soundResource = this.getClass().getClassLoader().getResource("RY-Light.wav");
        }

        //Set audio path to within java file
        AudioInputStream in = AudioSystem.getAudioInputStream(soundResource); <<<--- Error occurs here

        clip = AudioSystem.getClip();

        clip.open(in);
        clip.loop(Clip.LOOP_CONTINUOUSLY);  //get the file to loop continuously 

    }

    public void playAudioHi () throws Exception {
        //open the sound file as a Java input stream
        //High Score Music File
        if(RandomSongNum) {
            URL soundResource = this.getClass().getClassLoader().getResource("BH.wav");
        } else {
            URL soundResource = this.getClass().getClassLoader().getResource("RY.wav");
        }

        //Set audio path to within java file
        AudioInputStream in = AudioSystem.getAudioInputStream(soundResource); <<<--- Error occurs here

        clip = AudioSystem.getClip();

        clip.open(in);
        clip.loop(Clip.LOOP_CONTINUOUSLY);  //get the file to loop continuously 

    }

    public void stopAudio() {
        clip.stop();
    }



}

Answer 1

这是因为您在 if block 内声明变量 soundResource，然后尝试在 block 外访问它。

尝试这个模式:

// declare the variable outside the if block
URL soundResource;
if(RandomSongNum){
    soundResource = this.getClass().getClassLoader().getResource("BH-Lightest.wav");
} else {
    soundResource = this.getClass().getClassLoader().getResource("RY-Lightest.wav");
}

//Set audio path to within java file
AudioInputStream in = AudioSystem.getAudioInputStream(soundResource);