音量总是一样的？ [英] Volume always the same?

问题描述

我有以下代码，并且我想在按住音量按钮和当前音量之前获得前一个音量的差异。但是，当我调试时，我发现以前的和当前的音量总是相同的：

这是我的代码：

  package curlybrace.ruchir.ivebeenstuckfortwodays; 
 
导入android.content.Context; 
导入android.database.ContentObserver; 
导入android.media.AudioManager; 
导入android.os.Handler; 
 
 
 / ** 
 *由ruchir于2/5/2016创建。 
 * / 
 public class volumeCheck扩展ContentObserver {
 int previousVolume; 
上下文上下文; 
 
 public volumeCheck（Context c，Handler handler）{
 super（handler）; //创建一个新的处理程序
 context = c; //前面定义的变量上下文被设置为等于服务上下文c。 
 
 AudioManager audio =（AudioManager）context.getSystemService（Context.AUDIO_SERVICE）; //检索一个AudioManager来处理音量，铃声模式和音频路由的管理。 
 previousVolume = audio.getStreamVolume（AudioManager.STREAM_MUSIC）; //我们在调用`onChange`之前获得的音量
} 
 $ b @Override 
 public boolean deliverSelfNotifications（）{
 return super.deliverSelfNotifications（）; 
} 
 
 @Override 
 public void onChange（boolean selfChange）{
 super.onChange（selfChange）; 
 
 AudioManager audio =（AudioManager）context.getSystemService（Context.AUDIO_SERVICE）; 
 int currentVolume = audio.getStreamVolume（AudioManager.STREAM_MUSIC）; 
 
 processVolumeChange（previousVolume，currentVolume）; 
} 
 
 public void processVolumeChange（int previousVolume，int currentVolume）{
 
 MyService mService = new MyService（）; 
 mService.volumeCheck（previousVolume  -  currentVolume）; //在我的服务中的方法
 
 $ b} 
} 
  

我一直试图弄清楚这个问题2天了，但我不知道为什么这些值是相同的。请帮助。

编辑：

在我的服务的 onCreate中有以下代码：

  mSettingsContentObserver = new volumeCheck（this，new Handler（））; 
 getApplicationContext（）。getContentResolver（）。registerContentObserver（android.provider.Settings.System.CONTENT_URI，true，mSettingsContentObserver）; 
  

谢谢

解决方案您可能不会更改设备上的媒体音量。要验证进入设置 - >声音&通知并尝试更改在那里找到的媒体音量。

您可能还想在更改后更新您的 previousVolume ：

  @Override 
 public void onChange（boolean selfChange）{
 super.onChange（selfChange）; 
 
 AudioManager audio =（AudioManager）context.getSystemService（Context.AUDIO_SERVICE）; 
 int currentVolume = audio.getStreamVolume（AudioManager.STREAM_MUSIC）; 
 
 processVolumeChange（currentVolume）; 
} 
 
 public void processVolumeChange（int currentVolume）{
 MyService mService = new MyService（）; 
 mService.volumeCheck（previousVolume  -  currentVolume）; //我的服务中的方法
 previousVolume = currentVolume; 
} 
  

I have the following code, and I want to get the difference of the previous volume before holding the volume button and the current volume. But, when I was debugging, I found that the previous and current volume is always the same:

Here is my code:

package curlybrace.ruchir.ivebeenstuckfortwodays;

import android.content.Context;
import android.database.ContentObserver;
import android.media.AudioManager;
import android.os.Handler;


/**
 * Created by ruchir on 2/5/2016.
 */
public class volumeCheck extends ContentObserver {
    int previousVolume;
    Context context;

    public volumeCheck(Context c, Handler handler) {
        super(handler); //Creates a new handler
        context=c; //variable context, defined earlier, is set equal to c, context of service.

        AudioManager audio = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE); //retrieve an AudioManager for handling management of volume, ringer modes and audio routing.
        previousVolume = audio.getStreamVolume(AudioManager.STREAM_MUSIC); //The volume that we get before the `onChange` is called
    }

    @Override
    public boolean deliverSelfNotifications() {
        return super.deliverSelfNotifications();
    }

    @Override
    public void onChange(boolean selfChange) {
        super.onChange(selfChange);

        AudioManager audio = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
        int currentVolume = audio.getStreamVolume(AudioManager.STREAM_MUSIC);

        processVolumeChange(previousVolume, currentVolume);
    }

    public void processVolumeChange(int previousVolume, int currentVolume) {

        MyService mService = new MyService();
        mService.volumeCheck(previousVolume - currentVolume); //Method in my service


    }
}

I have been trying to figure this out for 2 days now, but I don't know why the values are the same. Please help.

Edit:

I have the following code in my service's onCreate:

     mSettingsContentObserver = new volumeCheck(this, new Handler());
   getApplicationContext().getContentResolver().registerContentObserver(android.provider.Settings.System.CONTENT_URI, true, mSettingsContentObserver);

Thanks

解决方案

You probably aren't changing the media volume on your device. To verify go to Settings->Sound & Notification and try changing the Media volume found there.

You probably also want to update update your previousVolume after a change too:

@Override
public void onChange(boolean selfChange) {
    super.onChange(selfChange);

    AudioManager audio = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
    int currentVolume = audio.getStreamVolume(AudioManager.STREAM_MUSIC);

    processVolumeChange(currentVolume);
}

public void processVolumeChange(int currentVolume) {
    MyService mService = new MyService();
    mService.volumeCheck(previousVolume - currentVolume); //Method in my service
    previousVolume = currentVolume;
}

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