java - 播放文件时出错 : NullPointerException in Android

Question

我想在 android 中播放 mp3 文件，但出现此错误:

java.lang.NullPointerException at HelloAndroid.playMusic

下面是我的代码

package com.bestvalue.hello;
/*import android.util.Log;*/
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import android.media.MediaPlayer;
import android.net.Uri;

public class HelloAndroid extends Activity {

    public static final String DebugTag = "LogInfo";
    public MediaPlayer mp;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        TextView tv = new TextView(this);        
        tv.setText("keke napep");
        playMusic();
        setContentView(tv);        
        Log.i(DebugTag, "Info about my app na");                
    }


    public void playMusic () {
        try {
            Uri fileName = Uri.parse("http://www.perlgurl.org/podcast/archives/podcasts/PerlgurlPromo.mp3");
            mp= MediaPlayer.create(this, fileName);
            mp.start();
        } catch (Exception e){
            Log.e(DebugTag, "Error Playing File", e);
        }
    }

    @Override
    protected void onStop() {
        if (mp != null) {
            mp.stop();
            mp.release();
        }
        super.onStop();
    }
}

我该如何解决这个错误？

谢谢

更新

package com.bestvalue.hello;
/*import android.util.Log;*/
import android.app.Activity;
//import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import android.media.AudioManager;
import android.media.MediaPlayer;


public class HelloAndroid extends Activity {

    public static final String DebugTag = "LogInfo";
    private MediaPlayer mp = new MediaPlayer();

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        TextView tv = new TextView(this);        
        tv.setText("keke napep");
        playMusic();
        setContentView(tv);                           
    }

    public void playMusic () {
        try {
            String url = "http://www.perlgurl.org/podcast/archives/podcasts/PerlgurlPromo.mp3";
            mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
            mp.setDataSource(url);
            mp.prepare(); 
            mp.start();         
        } catch (Exception e){
            Log.e(DebugTag, "Error Playing File", e);
        }
    }

    @Override
    protected void onStop() {
        if (mp != null) {
            mp.stop();
            mp.release();
        }
        super.onStop();
    }
}

实现一些答案后，我现在收到此错误:java.io.IOException:准备失败.: status = 0x1

Answer 1

在 mp.start(); 之前添加 mp.prepare();