ECHONEST 4 NULL指针异常

Question

下面是我的代码，我不明白是什么原因导致了"ECHONEST 4空指针异常“：

package com.main;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import  java.util.Map;
import com.echonest.api.v4.EchoNestAPI;
import com.echonest.api.v4.EchoNestException;
import com.echonest.api.v4.Track;
import com.echonest.api.v4.TrackAnalysis;


public class SongAnalysis {
    private static final String API_KEY = "14CPBOK0IFN0HRC0R";

    public String getTempo(String fileName){
        return null;
    }

    public static void main (String [] args)throws EchoNestException, IOException{

        EchoNestAPI echoNest = new EchoNestAPI(API_KEY);
        File file = new File("C:\\Users\\wooh\\workspace\\SongAnalysis\\songs\\b.mp3");
        Track track = echoNest.uploadTrack(file,false );
        track.waitForAnalysis(30000);
        TrackAnalysis a = track.getAnalysis();
        System.out.println("Tempo" + a.getTempo());
    }
}

Answer 1

您的NPE可能出现的情况如下：

• echoNest is null.
• track is null.
• a is null。

您可能希望确定NullPointerException发生的具体位置，然后确保在实例化对象时返回所需的对象。