Android M Light and Dark status bar programmatically - how to make it dark again?

Question

In the Android M we have ability to make status bar icons dark. To do that we can specify attribute in the theme\'s xml:

Answer 1

I base on @Aracem and @Carlos Hernández Gil but I think it will easy to understand if we use bitwise XOR (^ operator in Java)

private void setLightStatusBar(Activity activity) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        int flags = activity.getWindow().getDecorView().getSystemUiVisibility(); // get current flag
        flags |= View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;   // add LIGHT_STATUS_BAR to flag
        activity.getWindow().getDecorView().setSystemUiVisibility(flags); 
        activity.getWindow().setStatusBarColor(Color.GRAY); // optional
    }
}

private void clearLightStatusBar(Activity activity) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        int flags = activity.getWindow().getDecorView().getSystemUiVisibility(); // get current flag
        flags = flags ^ View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR; // use XOR here for remove LIGHT_STATUS_BAR from flags
        activity.getWindow().getDecorView().setSystemUiVisibility(flags);
        activity.getWindow().setStatusBarColor(Color.GREEN); // optional
    }
}

Explain

First, look at SYSTEM_UI_FLAG_LIGHT_STATUS_BAR and setSystemUiVisibility

/**
 * Flag for {@link #setSystemUiVisibility(int)}: Requests the status bar to draw in a mode that
 * is compatible with light status bar backgrounds.
 */
public static final int SYSTEM_UI_FLAG_LIGHT_STATUS_BAR = 0x00002000;

public void setSystemUiVisibility(int visibility) {
    if (visibility != mSystemUiVisibility) {
        mSystemUiVisibility = visibility;
        ...
    }
}

I think 2 lines code below is quite hard to understand

flags |= View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR; // for set light status bar
flags = flags ^ View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR; // for clear light status bar

At first look, I just think we can use simple like

flags = View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR; // for set light status bar
flags = 0; // for clear light status bar (0 <=> LIGHT_STATUS_BAR <=> default systemUiVisibility)

But we should use | and ^ because
Example, we want to set both status bar and navigationbar to light, then we will use

flags = View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR | View.View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;
activity.getWindow().getDecorView().setSystemUiVisibility(flags);

When we don't want status bar is light anymore, we can use

flags = View.View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;
activity.getWindow().getDecorView().setSystemUiVisibility(flags);

OR

flags = activity.getWindow().getDecorView().getSystemUiVisibility();
flags = flags ^ View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR; 
activity.getWindow().getDecorView().setSystemUiVisibility(flags);

To know more why we use | and ^, I think the tutorial below may help https://medium.com/@JakobUlbrich/flag-attributes-in-android-how-to-use-them-ac4ec8aee7d1 Here is my understand. Hope this help