Java 执行android应用程序时出现错误

我尝试按顺序复制一些视频，这是代码和错误消息。我在eclipse中使用Run->Debug Configurations选项创建sd卡，它是2GB sd卡。我把一些视频复制到sd卡上。所以，我感谢你的帮助。谢谢

MovieG.java

package com.example.movieg;

import java.io.File;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.os.Bundle; 
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.widget.MediaController;
import android.widget.VideoView; 
import android.annotation.SuppressLint;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;

public class MovieG extends Activity {

public VideoView videoView;
public String ex_name;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_movie_g);

    ex_name = getIntent().getExtras().getString("video_name");

    MediaController mediaController = new MediaController(this);
    mediaController.setAnchorView(videoView);
    videoView.setMediaController(new MediaController(this));
    handler.sendEmptyMessage(1);
}

@SuppressLint("HandlerLeak")
Handler handler = new Handler(){

    public void handleMessage(Message msg){

        int pos=msg.what;
        if (pos == 1){

            File ex_name = null;
                videoView.setVideoPath(Environment.getExternalStorageDirectory()+"/"+ex_name+".mp4");
            videoView.requestFocus();
            videoView.start();

            Log.d("Before Video Finish", "i m in before video finish");
            videoView.setOnCompletionListener(new OnCompletionListener() {
                @Override
                public void onCompletion(MediaPlayer mp) {
                    finish();
                }
            });
          }
       }
    };

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.movie_g, menu);
    return true;
}

}

AndroidManifest.xml

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

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="18" />

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

    <activity
        android:name="com.example.movieg.MovieG"
        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>

---

您应该验证

getIntent（）

是否有额外功能：

if (getIntent().getExtras() != null)
    ex_name = getIntent().getExtras().getString("video_name");

然后，您需要考虑到

ex_name

在代码后面为空

---

第二件事是，您从不初始化

videoView

变量。您需要先创建一个实例，然后才能在

onCreate（）

中使用它。您尚未初始化videoview：

videoView =(VideoView)findViewById(R.id.your_id);

---

在第28行之前

videoView

实例也为空

videoView =(VideoView)findViewById(R.id.your_id);