What do the the flag parameter means and range of possible min and max of droid device

问题

1. I want to know what is flag(or what are the possible values for flag) in

   audiomanager.setStreamVolume (int streamType, int index, int flags);

2. I know we can get the maximum stream using

   audiomanger.getMaxStream(audioManager.getStreamMax(AudioManager.STREAM_MUSIC));

But in some device it gives 13,15, it depends on Android version or device hardware and what is it range(minimum possible value, maximum possible value)

Sets the volume index for a particular stream.

This method has no effect if the device implements a fixed volume policy as indicated by isVolumeFixed().// what does it mean.

Parameters

streamType  The stream whose volume index should be set.

index   The volume index to set. See getStreamMaxVolume(int) for the largest valid value.

flags   One or more flags. // what are these flags 

回答1:

About the flag parameter: There are some flags defined in AudioManager.java. You can use any one of them to get the desired affect. example :

audioManager.setStreamVolume(audioManager.STREAM_MUSIC,progress,AudioManager.FLAG_SHOW_UI);

or simply

audioManager.setStreamVolume(audioManager.STREAM_MUSIC,progress,1);

here is the code segment from AudioManager.java showing how they are defined.

public static final int FLAG_SHOW_UI = 1 << 0;

/**
 * Whether to include ringer modes as possible options when changing volume.
 * For example, if true and volume level is 0 and the volume is adjusted
 * with {@link #ADJUST_LOWER}, then the ringer mode may switch the silent or
 * vibrate mode.
 * <p>
 * By default this is on for the ring stream. If this flag is included,
 * this behavior will be present regardless of the stream type being
 * affected by the ringer mode.
 *
 * @see #adjustVolume(int, int)
 * @see #adjustStreamVolume(int, int, int)
 */
public static final int FLAG_ALLOW_RINGER_MODES = 1 << 1;

/**
 * Whether to play a sound when changing the volume.
 * <p>
 * If this is given to {@link #adjustVolume(int, int)} or
 * {@link #adjustSuggestedStreamVolume(int, int, int)}, it may be ignored
 * in some cases (for example, the decided stream type is not
 * {@link AudioManager#STREAM_RING}, or the volume is being adjusted
 * downward).
 *
 * @see #adjustStreamVolume(int, int, int)
 * @see #adjustVolume(int, int)
 * @see #setStreamVolume(int, int, int)
 */
public static final int FLAG_PLAY_SOUND = 1 << 2;

/**
 * Removes any sounds/vibrate that may be in the queue, or are playing (related to
 * changing volume).
 */
public static final int FLAG_REMOVE_SOUND_AND_VIBRATE = 1 << 3;

/**
 * Whether to vibrate if going into the vibrate ringer mode.
 */
public static final int FLAG_VIBRATE = 1 << 4;

/**
 * Indicates to VolumePanel that the volume slider should be disabled as user
 * cannot change the stream volume
 * @hide
 */
public static final int FLAG_FIXED_VOLUME = 1 << 5;

/**
 * Indicates the volume set/adjust call is for Bluetooth absolute volume
 * @hide
 */
public static final int FLAG_BLUETOOTH_ABS_VOLUME = 1 << 6;

/**
 * Adjusting the volume was prevented due to silent mode, display a hint in the UI.
 * @hide
 */
public static final int FLAG_SHOW_SILENT_HINT = 1 << 7;

/**
 * Indicates the volume call is for Hdmi Cec system audio volume
 * @hide
 */
public static final int FLAG_HDMI_SYSTEM_AUDIO_VOLUME = 1 << 8;

/**
 * Indicates that this should only be handled if media is actively playing.
 * @hide
 */
public static final int FLAG_ACTIVE_MEDIA_ONLY = 1 << 9;

/**
 * Like FLAG_SHOW_UI, but only dialog warnings and confirmations, no sliders.
 * @hide
 */
public static final int FLAG_SHOW_UI_WARNINGS = 1 << 10;

/**
 * Adjusting the volume down from vibrated was prevented, display a hint in the UI.
 * @hide
 */
public static final int FLAG_SHOW_VIBRATE_HINT = 1 << 11;

/**
 * Adjusting the volume due to a hardware key press.
 * @hide
 */
public static final int FLAG_FROM_KEY = 1 << 12;

来源：https://stackoverflow.com/questions/27654620/what-do-the-the-flag-parameter-means-and-range-of-possible-min-and-max-of-droid