Android MediaPlayer mp3错误
有人知道为什么这不起作用吗?它在logcat中给了我一个非常基本的错误,所以我想我不必再加上这个 MainActivity.java:Android MediaPlayer mp3错误,android,android-mediaplayer,Android,Android Mediaplayer,有人知道为什么这不起作用吗?它在logcat中给了我一个非常基本的错误,所以我想我不必再加上这个 MainActivity.java: package com.sydcul.badluckboris; import android.media.MediaPlayer; import android.os.Bundle; import android.app.Activity; import android.view.View; import android.widget.ImageButton
package com.sydcul.badluckboris;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.ImageButton;
public class MainActivity extends Activity {
ImageButton boris;
MediaPlayer mp = MediaPlayer.create(getApplicationContext(), R.raw.ouch);
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
boris = (ImageButton) findViewById(R.id.ibBoris);
boris.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
mp.start();
}
});
}
}
activity_main.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ImageButton
android:id="@+id/ibBoris"
android:layout_width="250dp"
android:layout_height="300dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:contentDescription="@string/boris"
android:scaleType="fitXY"
android:src="@drawable/badluckboris2" />
</RelativeLayout>
以及AndroidManifest.xml:
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.sydcul.badluckboris"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/title_activity_main" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
编辑:LogCat:
10-31 17:15:05.670: E/AndroidRuntime(6500): FATAL EXCEPTION: main
10-31 17:15:05.670: E/AndroidRuntime(6500): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.sydcul.badluckboris/com.sydcul.badluckboris.MainActivity}: java.lang.NullPointerException
10-31 17:15:05.670: E/AndroidRuntime(6500): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1573)
10-31 17:15:05.670: E/AndroidRuntime(6500): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
10-31 17:15:05.670: E/AndroidRuntime(6500): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
10-31 17:15:05.670: E/AndroidRuntime(6500): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
10-31 17:15:05.670: E/AndroidRuntime(6500): at android.os.Handler.dispatchMessage(Handler.java:99)
10-31 17:15:05.670: E/AndroidRuntime(6500): at android.os.Looper.loop(Looper.java:130)
10-31 17:15:05.670: E/AndroidRuntime(6500): at android.app.ActivityThread.main(ActivityThread.java:3691)
10-31 17:15:05.670: E/AndroidRuntime(6500): at java.lang.reflect.Method.invokeNative(Native Method)
10-31 17:15:05.670: E/AndroidRuntime(6500): at java.lang.reflect.Method.invoke(Method.java:507)
10-31 17:15:05.670: E/AndroidRuntime(6500): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:912)
10-31 17:15:05.670: E/AndroidRuntime(6500): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:670)
10-31 17:15:05.670: E/AndroidRuntime(6500): at dalvik.system.NativeStart.main(Native Method)
10-31 17:15:05.670: E/AndroidRuntime(6500): Caused by: java.lang.NullPointerException
10-31 17:15:05.670: E/AndroidRuntime(6500): at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:100)
10-31 17:15:05.670: E/AndroidRuntime(6500): at com.sydcul.badluckboris.MainActivity.<init>(MainActivity.java:12)
10-31 17:15:05.670: E/AndroidRuntime(6500): at java.lang.Class.newInstanceImpl(Native Method)
10-31 17:15:05.670: E/AndroidRuntime(6500): at java.lang.Class.newInstance(Class.java:1409)
10-31 17:15:05.670: E/AndroidRuntime(6500): at android.app.Instrumentation.newActivity(Instrumentation.java:1024)
10-31 17:15:05.670: E/AndroidRuntime(6500): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1565)
10-31 17:15:05.670: E/AndroidRuntime(6500): ... 11 more
10-31 17:15:05.680: E/(1749): Dumpstate > /data/log/dumpstate_app_error
10-31 17:15:05.680: W/ActivityManager(1749): Force finishing activity com.sydcul.badluckboris/.MainActivity
10-3117:15:05.670:E/AndroidRuntime(6500):致命异常:主
10-31 17:15:05.670:E/AndroidRuntime(6500):java.lang.RuntimeException:无法实例化活动组件信息{com.sydcul.badluckboris/com.sydcul.badluckboris.MainActivity}:java.lang.NullPointerException
10-31 17:15:05.670:E/AndroidRuntime(6500):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1573)
10-31 17:15:05.670:E/AndroidRuntime(6500):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
10-31 17:15:05.670:E/AndroidRuntime(6500):在android.app.ActivityThread.access$1500(ActivityThread.java:117)
10-31 17:15:05.670:E/AndroidRuntime(6500):在android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
10-31 17:15:05.670:E/AndroidRuntime(6500):在android.os.Handler.dispatchMessage(Handler.java:99)上
10-3117:15:05.670:E/AndroidRuntime(6500):在android.os.Looper.loop(Looper.java:130)上
10-31 17:15:05.670:E/AndroidRuntime(6500):位于android.app.ActivityThread.main(ActivityThread.java:3691)
10-31 17:15:05.670:E/AndroidRuntime(6500):位于java.lang.reflect.Method.Invokenactive(本机方法)
10-3117:15:05.670:E/AndroidRuntime(6500):在java.lang.reflect.Method.invoke(Method.java:507)
10-31 17:15:05.670:E/AndroidRuntime(6500):在com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:912)
10-31 17:15:05.670:E/AndroidRuntime(6500):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:670)上
10-31 17:15:05.670:E/AndroidRuntime(6500):在dalvik.system.NativeStart.main(本机方法)
10-31 17:15:05.670:E/AndroidRuntime(6500):由以下原因引起:java.lang.NullPointerException
10-31 17:15:05.670:E/AndroidRuntime(6500):位于android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:100)
10-3117:15:05.670:E/AndroidRuntime(6500):位于com.sydcul.badluckboris.MainActivity。(MainActivity.java:12)
10-31 17:15:05.670:E/AndroidRuntime(6500):位于java.lang.Class.newInstanceImpl(本机方法)
10-3117:15:05.670:E/AndroidRuntime(6500):在java.lang.Class.newInstance(Class.java:1409)上
10-31 17:15:05.670:E/AndroidRuntime(6500):在android.app.Instrumentation.newActivity(Instrumentation.java:1024)上
10-31 17:15:05.670:E/AndroidRuntime(6500):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1565)
10-3117:15:05.670:E/AndroidRuntime(6500):。。。还有11个
10-31 17:15:05.680:E/(1749):转储状态>/data/log/Dumpstate\u app\u错误
10-31 17:15:05.680:W/ActivityManager(1749):强制完成活动com.sydcul.badluckboris/.main活动
提前谢谢。值得一提的是,我是一个机器人迷。做了很多VB.NET的工作。出错会更容易。从我所看到的我的猜测是,你从来没有准备好MediaPlayer,但我不确定。看到MediaPlayer设置在onCreate之外也有点奇怪,当时上下文可能还不完全有效,但我不知道这是否真的会导致问题。我同意,您不应该在类构造时尝试访问应用程序上下文,而应该在
onCreate
内部。