第二项活动不能打开

Question

我有一个应用程序与几个按钮，当用户点击任何按钮听起来音乐。问题是当活动打开时程序关闭。

只有在此活动中，eclipse错误并不表明发生了什么。

这是代码：

import android.app.Activity; 
import android.media.MediaPlayer; 
import android.os.Bundle; 
import android.view.View; 
import android.view.Window; 
import android.view.WindowManager; 
import android.widget.Button; 

public class GranjaActivity extends Activity { 


    Button atras, vaca, cerdo, caballo, oveja, gallina, perro ; 

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

     requestWindowFeature(Window.FEATURE_NO_TITLE); 
     getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 
           WindowManager.LayoutParams.FLAG_FULLSCREEN); 
     setContentView(R.layout.activity_granja); 

     atras = (Button) findViewById(R.id.btnatras); 
     vaca = (Button) findViewById(R.id.btnvaca); 
     cerdo = (Button) findViewById(R.id.btncerdo); 
     caballo = (Button) findViewById(R.id.btncaballo); 
     oveja = (Button) findViewById(R.id.btnoveja); 
     gallina = (Button) findViewById(R.id.btngallina); 
     perro = (Button) findViewById(R.id.btnperro); 

     //boton atras 
     atras.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       finish(); 

      } 
     }); 

     //boton vaca 
     vaca.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       MediaPlayer vaca = MediaPlayer.create(getApplicationContext(), R.raw.vaca); 

       vaca.start(); 

      } 
     }); 

     //boton cerdo 
     cerdo.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       MediaPlayer cerdo = MediaPlayer.create(getApplicationContext(), R.raw.cerdo); 

       cerdo.start(); 

      } 
     }); 

     //boton caballo 
     caballo.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       MediaPlayer caballo = MediaPlayer.create(getApplicationContext(), R.raw.caballo); 

       caballo.start(); 

      } 
     }); 

     //boton oveja 
     oveja.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       MediaPlayer oveja = MediaPlayer.create(getApplicationContext(), R.raw.oveja); 

       oveja.start(); 

      } 
     }); 

     //boton gallina 
     gallina.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       MediaPlayer gallina = MediaPlayer.create(getApplicationContext(), R.raw.gallina); 

       gallina.start(); 

      } 
     }); 

     //boton perro 
     perro.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       MediaPlayer perro = MediaPlayer.create(getApplicationContext(), R.raw.perro); 

       perro.start(); 

      } 
     }); 
    } 


} 

这是德XML代码：

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:background="@drawable/fondogranja" 
    android:orientation="vertical" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    tools:context="es.quovo.learninganimals.GranjaActivity" > 

    <Button 
     android:id="@+id/btnatras" 
     android:layout_width="50dp" 
     android:layout_height="50dp" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentTop="true" 
     android:layout_marginLeft="14dp" 
     android:layout_marginTop="8dp" 
     android:background="@drawable/back" /> 

    <Button 
     android:id="@+id/btnvaca" 
     android:layout_width="75dp" 
     android:layout_height="75dp" 
     android:layout_alignLeft="@+id/button1" 
     android:layout_alignParentBottom="true" 
     android:background="@drawable/botonvaca" /> 

    <Button 
     android:id="@+id/btncerdo" 
     android:layout_width="75dp" 
     android:layout_height="75dp" 
     android:layout_alignTop="@+id/btnvaca" 
     android:layout_toRightOf="@+id/btnvaca" 
     android:background="@drawable/botoncerdo" /> 

    <Button 
     android:id="@+id/btnperro" 
     android:layout_width="75dp" 
     android:layout_height="75dp" 
     android:layout_alignTop="@+id/btncerdo" 
     android:layout_toRightOf="@+id/btncerdo" 
     android:background="@drawable/botonperro"/> 

    <Button 
     android:id="@+id/btnoveja" 
     android:layout_width="75dp" 
     android:layout_height="75dp" 
     android:layout_alignTop="@+id/btnperro" 
     android:layout_toRightOf="@+id/btnperro" 
     android:background="@drawable/botonoveja"/> 

     <Button 
     android:id="@+id/btncaballo" 
     android:layout_width="75dp" 
     android:layout_height="75dp" 
     android:layout_alignTop="@+id/btnoveja" 
     android:layout_toRightOf="@+id/btnoveja" 
     android:background="@drawable/botonhorse" /> 

    <Button 
     android:id="@+id/btngallina" 
     android:layout_width="75dp" 
     android:layout_height="75dp" 
     android:layout_alignTop="@+id/btncaballo" 
     android:layout_toRightOf="@+id/btncaballo" 
     android:background="@drawable/botongallina" /> 

</RelativeLayout> 

Android清单：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="es.quovo.learninganimals" 
    android:versionCode="1" 
    android:versionName="1.0" > 

    <uses-sdk 
     android:minSdkVersion="8" 
     android:targetSdkVersion="21" /> 


    <application 
     android:allowBackup="true" 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" > 

     <activity 
      android:name=".MainActivity" 
      android:label="@string/app_name" 
      android:screenOrientation="landscape" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

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

     <activity 
      android:name=".GranjaActivity" 
      android:label="@string/title_activity_granja" 
      android:screenOrientation="landscape" > 
     </activity> 

     <activity 
      android:name=".SelvaActivity" 
      android:label="@string/title_activity_selva" 
      android:screenOrientation="landscape" > 
     </activity> 

     <activity 
      android:name=".OceanoActivity" 
      android:label="@string/title_activity_oceano" 
      android:screenOrientation="landscape" > 
     </activity> 
     <activity 
      android:name=".CieloActivity" 
      android:label="@string/title_activity_cielo" 
      android:screenOrientation="landscape" > 
     </activity> 
     <activity 
      android:name=".SabanaActivity" 
      android:label="@string/title_activity_sabana" 
      android:screenOrientation="landscape" > 
     </activity> 
     <activity 
      android:name=".CasaActivity" 
      android:label="@string/title_activity_casa" 
      android:screenOrientation="landscape" > 
     </activity> 

    </application> 

</manifest> 

Answer 1

requestWindowFeature(Window.FEATURE_NO_TITLE); 
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 
          WindowManager.LayoutParams.FLAG_FULLSCREEN); 

设置super.oncreate之前这些线

Answer 2

在活动的顶部，下方初始化您的媒体播放器，然后使用媒体播放器的全部proejct

MediaPlayer mpa=new MediaPlayer(); 

mpa = MediaPlayer.create(getApplicationContext(), R.raw.perro);