我的Android应用上出现新错误

Question

I received an error from a user that says:

 java.lang.NullPointerException
at com.jcolom.olakease.MainActivity$1.onClick(MainActivity.java:54)
at android.view.View.performClick(View.java:2408)
at android.view.View$PerformClick.run(View.java:8816)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4633)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
at dalvik.system.NativeStart.main(Native Method) 

My MainActivity is like this:

package com.jcolom.olakease;



import android.os.Bundle;
import android.app.Activity;

import java.io.InputStream;

import android.media.MediaPlayer;
import android.os.Bundle;

import android.app.Activity;
import android.content.Context;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;
import com.colom.ola.ke.ase.R;

public class MainActivity extends Activity {



        public Button olakease_button1;
        public Button olakease_button2;
        public Button olakease_button3;
        public Button olakease_button4;


        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);



            setContentView(R.layout.activity_main);
            olakease_button1 = (Button)findViewById(R.id.olakease_button1);
            olakease_button2 = (Button)findViewById(R.id.olakease_button2);
            olakease_button3 = (Button)findViewById(R.id.olakease_button3);
            olakease_button4 = (Button)findViewById(R.id.olakease_button4);
            InputStream fraw = null;
            fraw = getResources().openRawResource(R.raw.olakease1);
            fraw = getResources().openRawResource(R.raw.olakease2);
            fraw = getResources().openRawResource(R.raw.olakease3);


            olakease_button1.setOnClickListener(new OnClickListener() {
                public void onClick(View v) {


                    MediaPlayer mp = MediaPlayer.create(getBaseContext(),
                            R.raw.olakease1);
                            mp.start();

                }
            });



            olakease_button2.setOnClickListener(new OnClickListener() {
                public void onClick(View v) {


                    MediaPlayer mp = MediaPlayer.create(getBaseContext(),
                            R.raw.olakease2);
                            mp.start();

                }
            });


            olakease_button3.setOnClickListener(new OnClickListener() {
                public void onClick(View v) {


                    MediaPlayer mp = MediaPlayer.create(getBaseContext(),
                            R.raw.olakease3);
                            mp.start();

                }
            });

            olakease_button4.setOnClickListener(new OnClickListener() {
                public void onClick(View v) {


                    MediaPlayer mp = MediaPlayer.create(getBaseContext(),
                            R.raw.olakease4);
                            mp.start();

                }
            });




                }
    }

And my AndroidManifest is:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.colom.ola.ke.ase"
    android:versionCode="2"
    android:versionName="1.1" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="16" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/icono"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" 
        android:screenOrientation="portrait"
        android:name="MainActivity">
        <activity
            android:name="com.jcolom.olakease.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

What I have to do ?? Is it normal? Please, if you want to try my app on your mobile devices.. here it is the Play Store link: https://play.google.com/store/apps/details?id=com.colom.ola.ke.ase&feature=more_from_developer#?t=W251bGwsMSwyLDEwMiwiY29tLmNvbG9tLm9sYS5rZS5hc2UiXQ ..

Answer 1

在所有位置编写MainActivity.this而不是getBaseContext() ，它将解决您的问题。

Answer 2

 MediaPlayer mp = MediaPlayer.create(getBaseContext(),R.raw.olakease1); 

替换为MainActivity.this作为

 MediaPlayer mp = MediaPlayer.create(MainActivity.this, R.raw.olakease1); 

Answer 3

MediaPlayer.create can return null if creation failed. It may fail because it couldn't find the media or its an invalid format. http://developer.android.com/reference/android/media/MediaPlayer.html