Question

我想用mediaplayer和viewpager播放声音文件，但它不起作用。我收到错误消息

"Unfortunately, the process horizontalviewpaging has stopped"

（页面滑动和单击按钮事件）如何解决此问题？

package ro.ovidiuconeac.horizontalviewswiping;

import ro.ovidiuconeac.horizontalviewswiping.R;
import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class CustomPageChangeListener extends Activity implements OnPageChangeListener, OnClickListener {

  private MediaPlayer soundplay = null;

  @SuppressWarnings("unused")
  public void onCreate(Bundle savedInstanceState) {

    // load layout
    super.onCreate(savedInstanceState);
    setContentView(R.layout.page_1);
    MediaPlayer soundplay=MediaPlayer.create(this, R.raw.catsound); 
  }

  private Button buttonBlue   = null;
  private Button buttonYellow = null;
  private Button buttonRed    = null;
  private Activity context    = null;

  /**
   * Constructor
   */   
  public CustomPageChangeListener(Activity context) {
    this.context = context;

  }

  public void onPageScrollStateChanged(int arg0) {
    // TODO Auto-generated method stub

  }

  public void onPageScrolled(int arg0, float arg1, int arg2) {
     // TODO Auto-generated method stub

  }

  public void onPageSelected(int position) {

    switch (position) {
      case 0 : {
        ButtonBlue = (Button) context.findViewById(R.id.buttonBlue);
        buttonBlue.setOnClickListener(this);
        soundplay.start();  
        break;
      }
      case 1 : {
        buttonYellow = (Button) context.findViewById(R.id.buttonYellow);
        buttonYellow.setOnClickListener(this);
        soundplay.start();  
        break;
      }
      case 2 : {
        buttonRed = (Button) context.findViewById(R.id.buttonRed);
        buttonRed.setOnClickListener(this);
        soundplay.start();  
        break;
      }
    }   
  }

  public void onClick(View v) {

    // Click button blue
    if (buttonBlue != null && v.getId() == buttonBlue.getId()) {
      Toast.makeText(context, "Blue screen", Toast.LENGTH_SHORT).show();
      soundplay.start();    
    }

    // Click button yellow
    if (buttonYellow != null && v.getId() == buttonYellow.getId()) {
      Toast.makeText(context, "Yellow screen", Toast.LENGTH_SHORT).show();
      soundplay.start();        
    }

    // Click button red
    if (buttonRed != null && v.getId() == buttonRed.getId()) {
      Toast.makeText(context, "Red screen", Toast.LENGTH_SHORT).show();
      soundplay.start();    
    }   
  }
}

编辑出一个'答案'，这个问题确实是这个问题的额外信息。

> 09-01 08:38:04.964: E/AndroidRuntime(631): FATAL EXCEPTION: main
> 09-01 08:38:04.964: E/AndroidRuntime(631): java.lang.NullPointerException
> 09-01 08:38:04.964: E/AndroidRuntime(631): at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:101)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at ro.ovidiuconeac.horizontalviewswiping.CustomPageChangeListener.onClick(CustomPageChangeListener.java:80)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at android.view.View.performClick(View.java:4084)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at android.view.View$PerformClick.run(View.java:16966)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at android.os.Handler.handleCallback(Handler.java:615)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at android.os.Handler.dispatchMessage(Handler.java:92)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at android.os.Looper.loop(Looper.java:137)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at android.app.ActivityThread.main(ActivityThread.java:4745)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at java.lang.reflect.Method.invokeNative(Native Method)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at java.lang.reflect.Method.invoke(Method.java:511)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
> 09-01 08:38:04.964: E/AndroidRuntime(631): at dalvik.system.NativeStart.main(Native Method)

我更改了代码但没有工作。

package ro.ovidiuconeac.horizontalviewswiping;
import ro.ovidiuconeac.horizontalviewswiping.R;
import android.app.Activity;
import android.media.MediaPlayer;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class CustomPageChangeListener extends Activity implements OnPageChangeListener,     OnClickListener {

    MediaPlayer soundplay;
private Button buttonBlue   =   null;
private Button buttonYellow =   null;
private Button buttonRed    =   null;
private Activity context    =   null;

/**
 * Constructor
 */ 

public CustomPageChangeListener(Activity context) {
    this.context = context;

}

public void onPageScrollStateChanged(int arg0) {
    // TODO Auto-generated method stub

}

public void onPageScrolled(int arg0, float arg1, int arg2) {
    // TODO Auto-generated method stub

}

public void onPageSelected(int position) {

    switch (position) {
        case 0 : {
            buttonBlue = (Button)    context.findViewById(R.id.buttonBlue);
            buttonBlue.setOnClickListener(this);

            break;
        }
        case 1 : {
            buttonYellow = (Button) context.findViewById(R.id.buttonYellow);
            buttonYellow.setOnClickListener(this);
            break;
        }
        case 2 : {
            buttonRed = (Button) context.findViewById(R.id.buttonRed);
            buttonRed.setOnClickListener(this);

            break;
        }
    }   
}


public void onClick(View v) {

    // Click button blue
    if (buttonBlue != null && v.getId() == buttonBlue.getId()) {
        Toast.makeText(context, "Blue screen", Toast.LENGTH_SHORT).show();

    }

    // Click button yellow
    if (buttonYellow != null && v.getId() == buttonYellow.getId()) {

        //  Toast.makeText(context, "Yellow screen",   Toast.LENGTH_SHORT).show();
        playMusic();
    }

    // Click button red
    if (buttonRed != null && v.getId() == buttonRed.getId()) {
        Toast.makeText(context, "Red screen", Toast.LENGTH_SHORT).show();

    }   
}


public void playMusic () {
    soundplay = new MediaPlayer();
        try {   
        soundplay = MediaPlayer.create(getApplicationContext(), R.raw.bangyeni);
        soundplay.setVolume(1, 1);
        soundplay.start();

}
catch (Exception e){
    Toast.makeText(context, "Error", Toast.LENGTH_SHORT).show();
}   
}

}

Answer 1

    private MediaPlayer soundplay = null;
@SuppressWarnings("unused")
public void onCreate(Bundle savedInstanceState) {
// load layout

super.onCreate(savedInstanceState);
setContentView(R.layout.page_1);
MediaPlayer soundplay=MediaPlayer.create(this, R.raw.catsound);

}

该代码可能存在问题。您正在尝试播放null MediaPlayer。请编辑此行

     MediaPlayer soundplay=MediaPlayer.create(this, R.raw.catsound);

看起来像这样

    soundplay=MediaPlayer.create(this, R.raw.catsound);

你拥有它的方式是创建第二个MediaPLayer声音播放，其范围较小，在函数结束时死亡，将您之前设置的私有MediaPLayer保留为空。

我也认为你忘了投射一个新的MediaPlayer对象

     mp = new MediaPlayer();
     mp = MediaPlayer.create(getApplicationContext(), R.raw.sound);
     mp.setVolume(1, 1);
     mp.start();

这是我遵循的基本模式。

在用户事件上播放声音文件

1 个答案: