Eclipse中的Java錯誤-無法將soundresource解析為變量

Question

我正在嘗試將音樂文件導入到我的程序中，但也允許它在啟動時在其中兩個中隨機選擇。 我使用URL系統進行導入，因此我有一個名為soundResource的變量來完成此任務。

但是，每當我嘗試運行它時（使用Eclipse，盡管我認為這不是導致錯誤的原因），程序都會失敗，說明

soundResource cannot be resolved to a variable

我在其他主題中並未看到與此特別相關的內容，它與變量的范圍有關。 我如何在下面修復此代碼，以使變量彼此可見？

適用代碼：

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

這是因為您要在if塊中聲明變量soundResource ，然后嘗試在該塊外訪問它。

試試這個模式：

// 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);

Answer 2

該變量在if塊中聲明，因此僅在if范圍內。 因此，您以后不能在代碼中引用它。 將聲明移至if之前進行修復。

URL soundResource;
if(RandomSongNum){
    soundResource = this.getClass().getClassLoader().getResource("BH-Lightest.wav");
} else {
    soundResource = this.getClass().getClassLoader().getResource("RY-Lightest.wav");
}