我得到以下logcat的輸出:媒體播放器爲什麼會導致我的應用程序與空指針異常崩潰?
11-22 20:57:01.394: E/MediaPlayer(1647): error (1, 0)
11-22 20:57:01.404: D/MediaPlayer(1647): create failed:
11-22 20:57:01.404: D/MediaPlayer(1647): java.io.IOException: Prepare failed.: status=0x1
11-22 20:57:01.404: D/MediaPlayer(1647): at android.media.MediaPlayer.prepare(Native Method)
11-22 20:57:01.404: D/MediaPlayer(1647): at android.media.MediaPlayer.create(MediaPlayer.java:668)
11-22 20:57:01.404: D/MediaPlayer(1647): at com.jesse.abc.Apple.onCreate(Apple.java:25)
11-22 20:57:01.404: D/MediaPlayer(1647): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-22 20:57:01.404: D/MediaPlayer(1647): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
11-22 20:57:01.404: D/MediaPlayer(1647): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
11-22 20:57:01.404: D/MediaPlayer(1647): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
11-22 20:57:01.404: D/MediaPlayer(1647): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
11-22 20:57:01.404: D/MediaPlayer(1647): at android.os.Handler.dispatchMessage(Handler.java:99)
11-22 20:57:01.404: D/MediaPlayer(1647): at android.os.Looper.loop(Looper.java:123)
11-22 20:57:01.404: D/MediaPlayer(1647): at android.app.ActivityThread.main(ActivityThread.java:3683)
11-22 20:57:01.404: D/MediaPlayer(1647): at java.lang.reflect.Method.invokeNative(Native Method)
11-22 20:57:01.404: D/MediaPlayer(1647): at java.lang.reflect.Method.invoke(Method.java:507)
11-22 20:57:01.404: D/MediaPlayer(1647): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
11-22 20:57:01.404: D/MediaPlayer(1647): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
11-22 20:57:01.404: D/MediaPlayer(1647): at dalvik.system.NativeStart.main(Native Method)
11-22 20:57:01.414: D/AndroidRuntime(1647): Shutting down VM
11-22 20:57:01.414: W/dalvikvm(1647): threadid=1: thread exiting with uncaught exception (group=0x40015560)
11-22 20:57:01.414: E/AndroidRuntime(1647): FATAL EXCEPTION: main
11-22 20:57:01.414: E/AndroidRuntime(1647): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.jesse.abc/com.jesse.abc.Apple}: java.lang.NullPointerException
11-22 20:57:01.414: E/AndroidRuntime(1647): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
11-22 20:57:01.414: E/AndroidRuntime(1647): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
11-22 20:57:01.414: E/AndroidRuntime(1647): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
11-22 20:57:01.414: E/AndroidRuntime(1647): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
11-22 20:57:01.414: E/AndroidRuntime(1647): at android.os.Handler.dispatchMessage(Handler.java:99)
11-22 20:57:01.414: E/AndroidRuntime(1647): at android.os.Looper.loop(Looper.java:123)
11-22 20:57:01.414: E/AndroidRuntime(1647): at android.app.ActivityThread.main(ActivityThread.java:3683)
11-22 20:57:01.414: E/AndroidRuntime(1647): at java.lang.reflect.Method.invokeNative(Native Method)
11-22 20:57:01.414: E/AndroidRuntime(1647): at java.lang.reflect.Method.invoke(Method.java:507)
11-22 20:57:01.414: E/AndroidRuntime(1647): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
11-22 20:57:01.414: E/AndroidRuntime(1647): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
11-22 20:57:01.414: E/AndroidRuntime(1647): at dalvik.system.NativeStart.main(Native Method)
11-22 20:57:01.414: E/AndroidRuntime(1647): Caused by: java.lang.NullPointerException
11-22 20:57:01.414: E/AndroidRuntime(1647): at com.jesse.abc.Apple.onCreate(Apple.java:32)
11-22 20:57:01.414: E/AndroidRuntime(1647): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-22 20:57:01.414: E/AndroidRuntime(1647): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
11-22 20:57:01.414: E/AndroidRuntime(1647): ... 11 more
11-22 20:57:02.934: I/Process(1647): Sending signal. PID: 1647 SIG: 9
這是我的代碼:
我敢肯定,我的清單和佈局文件都OK。錯誤指向第32行,即myPlayer.start();
。當我在測試過程中重複地在各個活動之間來回切換時,纔會發生崩潰。任何幫助將不勝感激。
package com.jesse.abc;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
public class Car extends Activity{
MediaPlayer mPlayer;
MediaPlayer myPlayer;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.cletter);
mPlayer = MediaPlayer.create(this, R.raw.button_sound1);
myPlayer = MediaPlayer.create(this, R.raw.carsound);
final Button bButton = (Button)findViewById(R.id.cbackbutton);
final Button nButton = (Button)findViewById(R.id.cnextbutton);
final ImageButton cButton = (ImageButton)findViewById(R.id.cButton);
final Context ctx = this;
myPlayer.start();
bButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
mPlayer.start();
Intent myIntent = new Intent(v.getContext(), Ball.class);
ctx.startActivity(myIntent);
myPlayer.release();
}
});
nButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
mPlayer.start();
Intent myIntent2 = new Intent(v.getContext(), Duck.class);
ctx.startActivity(myIntent2);
myPlayer.release();
}
});
cButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
myPlayer.start();
}
});
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
// TODO Auto-generated method stub
if(keyCode==KeyEvent.KEYCODE_BACK){
this.startActivity(new Intent(Car.this, StartingPoint.class));
myPlayer.release();
finish();
}
return true;
}
}
對不起,我在調試時添加了該行。我試圖弄清楚它爲什麼會崩潰,這是我做的最後一件事。我會用原始代碼發佈另一個類。 – jessenave