Android soundpool 空指针异常

Posted 2023-02-25

【中文标题】Android soundpool 空指针异常

【英文标题】：Android soundpool null pointer exception

【发布时间】：2012-09-07 18:49:47

【问题描述】：

我想用 soundpool 播放声音文件。我在播放音频文件时收到错误消息。 （“不幸的是，galeri 的进程已停止”）如何在滑动页面时播放短声音？谢谢。

代码是；

package com.example.galeri;
import com.example.galeri.R;
import android.content.Context;
import android.media.AudioManager;
import android.media.SoundPool;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;

public class MyPagerAdapter extends  PagerAdapter
 private static final Context Context = null;
SoundPool snd;
int sescal;
public int getCount() 
    return 6;



public Object instantiateItem(View collection, int position) 

    LayoutInflater inflater = (LayoutInflater) collection.getContext()
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    this.setVolumeControlStream(AudioManager.STREAM_MUSIC);
    snd = new SoundPool(10, AudioManager.STREAM_MUSIC, 0);
    sescal = snd.load(Context, R.raw.ayna, 1);
    View view = null;

    int resId = 0;       
    switch (position) 
    case 0:
        resId = R.layout.farleft;
        break;
    case 1:
         resId = R.layout.left; // second
         view = inflater.inflate(resId, null);
         snd.play(sescal, 0.9f, 0.9f, 1, -1, 1f);
        break;
    case 2:
        resId = R.layout.middle;
        break;
    case 3:
        resId = R.layout.right;
        break;
    case 4:
        resId = R.layout.farright;
        break;
    case 5:
        resId = R.layout.other;
        break;
    

    ((ViewPager) collection).addView(view, 0);

    return view;
    

   private void setVolumeControlStream(int streamMusic) 
    // TODO Auto-generated method stub




 private void setVolumeControlStream(int streamMusic) 
    // TODO Auto-generated method stub



@SuppressWarnings("unused")
private Context getBaseContext() 
    // TODO Auto-generated method stub
    return null;



@SuppressWarnings("unused")
private PagerAdapter findViewById(int myfivepanelpager) 
    // TODO Auto-generated method stub
    return null;


@Override
public void destroyItem(View arg0, int arg1, Object arg2) 
    ((ViewPager) arg0).removeView((View) arg2);



@Override
public boolean isViewFromObject(View arg0, Object arg1) 
    return arg0 == ((View) arg1);



@Override
public Parcelable saveState() 
    return null;


public static Integer getItem(int position) 
    // TODO Auto-generated method stub
    return null;

Logcat;

09-07 18:37:28.169: E/AndroidRuntime(653): FATAL EXCEPTION: main
09-07 18:37:28.169: E/AndroidRuntime(653): java.lang.NullPointerException
09-07 18:37:28.169: E/AndroidRuntime(653):  at     android.media.SoundPool.load(SoundPool.java:191)
09-07 18:37:28.169: E/AndroidRuntime(653):  at com.example.galeri.MyPagerAdapter.instantiateItem(MyPagerAdapter.java:30)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.support.v4.view.PagerAdapter.instantiateItem(PagerAdapter.java:110)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:692)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.support.v4.view.ViewPager.populate(ViewPager.java:821)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.support.v4.view.ViewPager.populate(ViewPager.java:772)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1234)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.View.measure(View.java:15172)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.View.measure(View.java:15172)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.View.measure(View.java:15172)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:833)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.View.measure(View.java:15172)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
09-07 18:37:28.169: E/AndroidRuntime(653):  at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2148)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.View.measure(View.java:15172)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1848)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1100)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1273)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4212)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.Choreographer.doCallbacks(Choreographer.java:555)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.Choreographer.doFrame(Choreographer.java:525)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.os.Handler.handleCallback(Handler.java:615)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.os.Handler.dispatchMessage(Handler.java:92)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.os.Looper.loop(Looper.java:137)
09-07 18:37:28.169: E/AndroidRuntime(653):  at android.app.ActivityThread.main(ActivityThread.java:4745)
09-07 18:37:28.169: E/AndroidRuntime(653):  at     java.lang.reflect.Method.invokeNative(Native Method)
09-07 18:37:28.169: E/AndroidRuntime(653):  at java.lang.reflect.Method.invoke(Method.java:511)
09-07 18:37:28.169: E/AndroidRuntime(653):  at     com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
09-07 18:37:28.169: E/AndroidRuntime(653):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-07 18:37:28.169: E/AndroidRuntime(653):  at dalvik.system.NativeStart.main(Native     Method)

【问题讨论】：

最好将 Context 成员变量命名为 mContext 而不是 Context

【参考方案1】：

问题是您的 Context 变量被声明为 null 并且从未设置。

然后，在其 load() 方法中，SoundPool 调用 context.getResources().openRawResourceFd(resId) 并在此处获得 NullPointerException。

您可以从instantiateItem 方法的View collection 参数中获取有效的上下文。

所以尝试调用：

snd.load(collection.getContext(), R.raw.ayna, 1);

【讨论】：

sescal = snd.load(context.getResources().openRawResourceFd(resId), R.raw.ayna);真的吗？？