Java 多视频视图问题

我的应用程序包含5个按钮，每个按钮打开不同的视频视图，当我创建代码时，我在下面有红色标记：（new MediaController（此）），我试图解决它，但我不能

请给出建议，我是android开发的新手

谢谢

应用更改为：（new MediaController（this））后更新，获取另一个错误

我的代码：

public class MultipleButton extends Activity {
    String night;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

    }

    public void handleClick(View v){
        //Create an intent to start the new activity.
        Intent intent = new Intent();
        intent.setClass(this,My_videos.class);
        intent.putExtra("video",night);
        startActivity(intent);
    }
}

I/Process(25196): Sending signal. PID: 25196 SIG: 9
D/AndroidRuntime(25447): Shutting down VM
W/dalvikvm(25447): threadid=1: thread exiting with uncaught exception (group=0x40015578)
E/AndroidRuntime(25447): FATAL EXCEPTION: main
E/AndroidRuntime(25447): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tsn.dr/com.tsn.dr.My_videos}: java.lang.NullPointerException
E/AndroidRuntime(25447):at android.app.ActivityThread.performLaunchActivity (ActivityThread.java:1651) 
E/AndroidRuntime(25447):at android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:1667) 
E/AndroidRuntime(25447):at android.app.ActivityThread.access$1500 (ActivityThread.java:117)
E/AndroidRuntime(25447):at android.app.ActivityThread$H.handleMessage (ActivityThread.java:935)
E/AndroidRuntime(25447):at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(25447):at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime(25447):at android.app.ActivityThread.main(ActivityThread.java:3687)
E/AndroidRuntime(25447):at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(25447):at java.lang.reflect.Method.invoke(Method.java:507)
E/AndroidRuntime(25447):at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run (ZygoteInit.java:842)
E/AndroidRuntime(25447):at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:600)
E/AndroidRuntime(25447):at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(25447): Caused by: java.lang.NullPointerException
E/AndroidRuntime(25447):at com.tsn.dr.My_videos.initializeVideoViews (My_videos.java:31)
E/AndroidRuntime(25447):at com.tsn.dr.My_videos.onCreate(My_videos.java:24)
E/AndroidRuntime(25447):at android.app.Instrumentation.callActivityOnCreate (Instrumentation.java:1047)
E/AndroidRuntime(25447):at android.app.ActivityThread.performLaunchActivity (ActivityThread.java:1615)
E/AndroidRuntime(25447):    ... 11 more

多按钮类：

public class MultipleButton extends Activity {
    String night;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

    }

    public void handleClick(View v){
        //Create an intent to start the new activity.
        Intent intent = new Intent();
        intent.setClass(this,My_videos.class);
        intent.putExtra("video",night);
        startActivity(intent);
    }
}

I/Process(25196): Sending signal. PID: 25196 SIG: 9
D/AndroidRuntime(25447): Shutting down VM
W/dalvikvm(25447): threadid=1: thread exiting with uncaught exception (group=0x40015578)
E/AndroidRuntime(25447): FATAL EXCEPTION: main
E/AndroidRuntime(25447): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tsn.dr/com.tsn.dr.My_videos}: java.lang.NullPointerException
E/AndroidRuntime(25447):at android.app.ActivityThread.performLaunchActivity (ActivityThread.java:1651) 
E/AndroidRuntime(25447):at android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:1667) 
E/AndroidRuntime(25447):at android.app.ActivityThread.access$1500 (ActivityThread.java:117)
E/AndroidRuntime(25447):at android.app.ActivityThread$H.handleMessage (ActivityThread.java:935)
E/AndroidRuntime(25447):at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(25447):at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime(25447):at android.app.ActivityThread.main(ActivityThread.java:3687)
E/AndroidRuntime(25447):at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(25447):at java.lang.reflect.Method.invoke(Method.java:507)
E/AndroidRuntime(25447):at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run (ZygoteInit.java:842)
E/AndroidRuntime(25447):at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:600)
E/AndroidRuntime(25447):at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(25447): Caused by: java.lang.NullPointerException
E/AndroidRuntime(25447):at com.tsn.dr.My_videos.initializeVideoViews (My_videos.java:31)
E/AndroidRuntime(25447):at com.tsn.dr.My_videos.onCreate(My_videos.java:24)
E/AndroidRuntime(25447):at android.app.Instrumentation.callActivityOnCreate (Instrumentation.java:1047)
E/AndroidRuntime(25447):at android.app.ActivityThread.performLaunchActivity (ActivityThread.java:1615)
E/AndroidRuntime(25447):    ... 11 more

我的视频课程：strong文本

 public class My_videos extends Activity {
    private Button button;
    private VideoView vid;
    String night;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.video);


    initializeVideoViews(); }

    private void initializeVideoViews() {


        String night = getIntent().getStringExtra("video");

        if(night.equalsIgnoreCase("button1")){
        button = (Button) findViewById(R.id.button1);

        button.setOnClickListener(new OnClickListener() {

          public void onClick(View arg0) {

                 vid =(VideoView) findViewById(R.id.videoView1);
                 vid.setVideoURI(Uri.parse("android.resource://" +
                                      getPackageName() +"/"+R.raw.a));
            vid.setMediaController(new MediaController(My_videos.this));
                 vid.requestFocus();
                 vid.start();


                   }
                         });       }



         else if(night.equalsIgnoreCase("button2")){

         button = (Button) findViewById(R.id.button2);

            button.setOnClickListener(new OnClickListener() {

              public void onClick(View arg0) {

              vid = (VideoView) findViewById(R.id.videoView1);
                 vid.setVideoURI(Uri.parse("android.resource://" +
                                       getPackageName() +"/"+R.raw.b));
            vid.setMediaController(new MediaController(My_videos.this));
                 vid.requestFocus();



              }
            });}

         else if(night.equalsIgnoreCase("button3")){

         button = (Button) findViewById(R.id.button3);

            button.setOnClickListener(new OnClickListener() {

              public void onClick(View arg0) {

              vid = (VideoView) findViewById(R.id.videoView1);
                 vid.setVideoURI(Uri.parse("android.resource://" +
                                       getPackageName() +"/"+R.raw.c));
            vid.setMediaController(new MediaController(My_videos.this));
                     vid.requestFocus();



              }
            });}

         else if(night.equalsIgnoreCase("button4")){

         button = (Button) findViewById(R.id.button4);

            button.setOnClickListener(new OnClickListener() {

              public void onClick(View arg0) {

              vid = (VideoView) findViewById(R.id.videoView1);
                 vid.setVideoURI(Uri.parse("android.resource://" +
                                     getPackageName() +"/"+R.raw.d));
            vid.setMediaController(new MediaController(My_videos.this));
                     vid.requestFocus();


              }
            });}
         else if(night.equalsIgnoreCase("button5")){

         button = (Button) findViewById(R.id.button5);

            button.setOnClickListener(new OnClickListener() {

              public void onClick(View arg0) {

              vid = (VideoView) findViewById(R.id.videoView1);
                 vid.setVideoURI(Uri.parse("android.resource://" +
                                    getPackageName() +"/"+R.raw.e));
            vid.setMediaController(new MediaController(My_videos.this));
                     vid.requestFocus();


              }
            });

        }}}

更新：strong文本

 public class My_videos extends Activity {
    private Button button;
    private VideoView vid;
    String night;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.video);


    initializeVideoViews(); }

    private void initializeVideoViews() {


        String night = getIntent().getStringExtra("video");

        if(night.equalsIgnoreCase("button1")){
        button = (Button) findViewById(R.id.button1);

        button.setOnClickListener(new OnClickListener() {

          public void onClick(View arg0) {

                 vid =(VideoView) findViewById(R.id.videoView1);
                 vid.setVideoURI(Uri.parse("android.resource://" +
                                      getPackageName() +"/"+R.raw.a));
            vid.setMediaController(new MediaController(My_videos.this));
                 vid.requestFocus();
                 vid.start();


                   }
                         });       }



         else if(night.equalsIgnoreCase("button2")){

         button = (Button) findViewById(R.id.button2);

            button.setOnClickListener(new OnClickListener() {

              public void onClick(View arg0) {

              vid = (VideoView) findViewById(R.id.videoView1);
                 vid.setVideoURI(Uri.parse("android.resource://" +
                                       getPackageName() +"/"+R.raw.b));
            vid.setMediaController(new MediaController(My_videos.this));
                 vid.requestFocus();



              }
            });}

         else if(night.equalsIgnoreCase("button3")){

         button = (Button) findViewById(R.id.button3);

            button.setOnClickListener(new OnClickListener() {

              public void onClick(View arg0) {

              vid = (VideoView) findViewById(R.id.videoView1);
                 vid.setVideoURI(Uri.parse("android.resource://" +
                                       getPackageName() +"/"+R.raw.c));
            vid.setMediaController(new MediaController(My_videos.this));
                     vid.requestFocus();



              }
            });}

         else if(night.equalsIgnoreCase("button4")){

         button = (Button) findViewById(R.id.button4);

            button.setOnClickListener(new OnClickListener() {

              public void onClick(View arg0) {

              vid = (VideoView) findViewById(R.id.videoView1);
                 vid.setVideoURI(Uri.parse("android.resource://" +
                                     getPackageName() +"/"+R.raw.d));
            vid.setMediaController(new MediaController(My_videos.this));
                     vid.requestFocus();


              }
            });}
         else if(night.equalsIgnoreCase("button5")){

         button = (Button) findViewById(R.id.button5);

            button.setOnClickListener(new OnClickListener() {

              public void onClick(View arg0) {

              vid = (VideoView) findViewById(R.id.videoView1);
                 vid.setVideoURI(Uri.parse("android.resource://" +
                                    getPackageName() +"/"+R.raw.e));
            vid.setMediaController(new MediaController(My_videos.this));
                     vid.requestFocus();


              }
            });

        }}}

LOGCAT:

public class MultipleButton extends Activity {
    String night;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

    }

    public void handleClick(View v){
        //Create an intent to start the new activity.
        Intent intent = new Intent();
        intent.setClass(this,My_videos.class);
        intent.putExtra("video",night);
        startActivity(intent);
    }
}

I/Process(25196): Sending signal. PID: 25196 SIG: 9
D/AndroidRuntime(25447): Shutting down VM
W/dalvikvm(25447): threadid=1: thread exiting with uncaught exception (group=0x40015578)
E/AndroidRuntime(25447): FATAL EXCEPTION: main
E/AndroidRuntime(25447): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tsn.dr/com.tsn.dr.My_videos}: java.lang.NullPointerException
E/AndroidRuntime(25447):at android.app.ActivityThread.performLaunchActivity (ActivityThread.java:1651) 
E/AndroidRuntime(25447):at android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:1667) 
E/AndroidRuntime(25447):at android.app.ActivityThread.access$1500 (ActivityThread.java:117)
E/AndroidRuntime(25447):at android.app.ActivityThread$H.handleMessage (ActivityThread.java:935)
E/AndroidRuntime(25447):at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(25447):at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime(25447):at android.app.ActivityThread.main(ActivityThread.java:3687)
E/AndroidRuntime(25447):at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(25447):at java.lang.reflect.Method.invoke(Method.java:507)
E/AndroidRuntime(25447):at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run (ZygoteInit.java:842)
E/AndroidRuntime(25447):at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:600)
E/AndroidRuntime(25447):at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(25447): Caused by: java.lang.NullPointerException
E/AndroidRuntime(25447):at com.tsn.dr.My_videos.initializeVideoViews (My_videos.java:31)
E/AndroidRuntime(25447):at com.tsn.dr.My_videos.onCreate(My_videos.java:24)
E/AndroidRuntime(25447):at android.app.Instrumentation.callActivityOnCreate (Instrumentation.java:1047)
E/AndroidRuntime(25447):at android.app.ActivityThread.performLaunchActivity (ActivityThread.java:1615)
E/AndroidRuntime(25447):    ... 11 more

manifest.xml：

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.tsn.dr"
android:versionCode="1"
android:versionName="1.0" >

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

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name" >
    <activity
        android:name=".MultipleButton"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".My_videos"
              android:label="@string/app_name">
    </activity>
</application>

main.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:onClick="handleClick"
        android:text="Button" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:onClick="handleClick"
        android:text="Button" />

    <Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:onClick="handleClick"
        android:text="Button" />

    <Button
        android:id="@+id/button4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:onClick="handleClick"
        android:text="Button" />

    <Button
        android:id="@+id/button5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:onClick="handleClick"
        android:text="Button" />
</LinearLayout>

video.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <VideoView
        android:id="@+id/videoView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

---

在按钮单击内部使用这组行将导致错误

   setMediaController(new MediaController(this));

因为上面一行中的这个指的是按钮实例，而不是那个按钮实例，请尝试使用这个

 setMediaController(new MediaController(My_videos.this));

---

写下下面的任意一行代码

MultipleButton.java

public class MultipleButton extends Activity {

    String night;
    Button mBtn1, mBtn2, mBtn3, mBtn4, mBtn5;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mBtn1=(Button)findViewById(R.id.button1);
        mBtn1.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                night="button1";
                Intent intent = new Intent();
                intent.setClass(MultipleButton.this, My_videos.class);
                intent.putExtra("video", night);
                startActivity(intent);
            }
        });

        mBtn2=(Button)findViewById(R.id.button2);
        mBtn2.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                night="button2";
                Intent intent = new Intent();
                intent.setClass(MultipleButton.this, My_videos.class);
                intent.putExtra("video", night);
                startActivity(intent);
            }
        });

        mBtn3=(Button)findViewById(R.id.button3);
        mBtn3.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                night="button3";
                Intent intent = new Intent();
                intent.setClass(MultipleButton.this, My_videos.class);
                intent.putExtra("video", night);
                startActivity(intent);
            }
        });

        mBtn4=(Button)findViewById(R.id.button4);
        mBtn4.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                night="button4";
                Intent intent = new Intent();
                intent.setClass(MultipleButton.this, My_videos.class);
                intent.putExtra("video", night);
                startActivity(intent);
            }
        });

        mBtn5=(Button)findViewById(R.id.button5);
        mBtn5.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                night="button5";
                Intent intent = new Intent();
                intent.setClass(MultipleButton.this, My_videos.class);
                intent.putExtra("video", night);
                startActivity(intent);
            }
        });
    }
}

My_videos.java

public class My_videos extends Activity {
    private VideoView vid;
    String night;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.video);

        Bundle bdl = getIntent().getExtras();
        night = bdl.getString("video");

        vid = (VideoView) findViewById(R.id.videoView1);

        if (night.equalsIgnoreCase("button1")) {
            vid.setVideoURI(Uri.parse("android.resource://" + getPackageName()
                    + "/" + R.raw.a));
            vid.setMediaController(new MediaController(My_videos.this));
            vid.requestFocus();
            vid.start();
        } else if (night.equalsIgnoreCase("button2")) {
            vid.setVideoURI(Uri.parse("android.resource://" + getPackageName()
                    + "/" + R.raw.b));
            vid.setMediaController(new MediaController(My_videos.this));
            vid.requestFocus();
            vid.start();
        } else if (night.equalsIgnoreCase("button3")) {
            vid.setVideoURI(Uri.parse("android.resource://" + getPackageName()
                    + "/" + R.raw.c));
            vid.setMediaController(new MediaController(My_videos.this));
            vid.requestFocus();
            vid.start();
        } else if (night.equalsIgnoreCase("button4")) {
            vid.setVideoURI(Uri.parse("android.resource://" + getPackageName()
                    + "/" + R.raw.d));
            vid.setMediaController(new MediaController(My_videos.this));
            vid.requestFocus();
            vid.start();
        } else if (night.equalsIgnoreCase("button5")) {
            vid.setVideoURI(Uri.parse("android.resource://" + getPackageName()
                    + "/" + R.raw.e));
            vid.setMediaController(new MediaController(My_videos.this));
            vid.requestFocus();
            vid.start();
        }
    }
}

main.xml：-

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="Button" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="Button" />

    <Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="Button" />

    <Button
        android:id="@+id/button4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="Button" />

    <Button
        android:id="@+id/button5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="Button" />

</LinearLayout>

---

尝试在清单文件中为My_videos活动添加意图过滤器，而不是My_videos.java类

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

更新----

---

您正在尝试查找video.xml中没有的视图、按钮1、按钮2等。所以它给出了空指针异常。

您的My_videos类是否在同一个包中？我的意思是，在com.tsn.dr？@Raghu Nagaraju是的coruse我亲爱的你的logcat显示了在寻找活动时的问题，但你在MediaController中告诉了问题。。你确定，这是最新的日志吗？