SoundSettings.java 文件源码

private void initIncreasingRing(PreferenceCategory root) {
    mIncreasingRing = (TwoStatePreference)
            root.findPreference(CMSettings.System.INCREASING_RING);
    mIncreasingRingVolume = (IncreasingRingVolumePreference)
            root.findPreference(KEY_INCREASING_RING_VOLUME);

    if (!mVoiceCapable) {
        if (mIncreasingRing != null) {
            root.removePreference(mIncreasingRing);
            mIncreasingRing = null;
        }
        if (mIncreasingRingVolume != null) {
            root.removePreference(mIncreasingRingVolume);
            mIncreasingRingVolume = null;
        }
    } else {
        if (mIncreasingRingVolume != null) {
            mIncreasingRingVolume.setCallback(mIncreasingRingVolumeCallback);
        }
    }
}