Java 调用start（）时MediaPlayer onClick崩溃

我有一个只显示一张图片的应用程序，它是通过

毕加索

实现的。如果我用一个简单的祝酒词替换内容，

onClick

效果很好，所以它一定是

MediaPlayer

调用的。我不知道为什么它一直在崩溃

package com.example.andrew.crossfade;
import android.media.MediaPlayer;
import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import com.squareup.picasso.Picasso;

public class MainActivity extends ActionBarActivity{

MediaPlayer mp;

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    getSupportActionBar().hide();
    setContentView(R.layout.activity_main);
    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment())
                .commit();
    }

    ImageView imageView = (ImageView) findViewById(R.id.imageView);
    imageView.setClickable(true);

    Picasso.with(this)
            .load("http://i.imgur.com/vpeH7S2.jpg")
            .into(imageView);

    imageView.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            mp = MediaPlayer.create(MainActivity.this, R.raw.later);
            mp.start();
        }

    });

}
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);
        return rootView;
    }
}

}

XML：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:id="@+id/container"
android:layout_width="match_parent" android:layout_height="match_parent"
tools:context=".MainActivity" tools:ignore="MergeRootFrame" >

<ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/imageView"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"

    />

---

您的代码中有些内容为空

java.lang.NullPointerException

启动前调用mp.prepare（）

---

并确保R.raw.later可为media player播放音频

结果是media player无法播放WAV。早些时候我就想到了这一点，但我决定不再重复检查，因为我认为现在一切都可以玩wavs了。猜测应该始终遵循第一直觉。谢谢

10-29 12:12:07.343  18409-18409/com.example.andrew.crossfade W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x41f38da0)
10-29 12:12:07.343  18409-18409/com.example.andrew.crossfade E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.andrew.crossfade, PID: 18409
java.lang.NullPointerException
        at com.example.andrew.crossfade.MainActivity$1.onClick(MainActivity.java:47)
        at android.view.View.performClick(View.java:4633)
        at android.view.View$PerformClick.run(View.java:19330)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:157)
        at android.app.ActivityThread.main(ActivityThread.java:5356)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
        at dalvik.system.NativeStart.main(Native Method)