Check for navigation bar

问题

I am trying to check to see whether the android navigation bar is present on load so that I can adjust a layout accordingly, does anyone have any suggestions?

This is the navigation bar I am trying to detect:

P.S. All I have found so far are \'bad\' ways to try and remove the bar, which I dont want to do.

回答1:

Took me some time but I've found a more reliable way than relying on hasPermanentMenuKey() which doesn't work for newer phones like the HTC One which have no menu key but do have home & back keys so don't need (or show) the soft navigation bar. To get around this try the following code which checks for a back button too:

boolean hasMenuKey = ViewConfiguration.get(context).hasPermanentMenuKey();
boolean hasBackKey = KeyCharacterMap.deviceHasKey(KeyEvent.KEYCODE_BACK);

if(!hasMenuKey && !hasBackKey) {
    // Do whatever you need to do, this device has a navigation bar
}

回答2:

There's no reliable way to check for a navigation bar. Using KeyCharacterMap.deviceHasKey you can check if certain physical keys are present on the device, but this information is not very useful since devices with physical keys can still have a navigation bar. Devices like the OnePlus One, or any device running a custom rom, have an option in the settings that disables the physical keys, and adds a navigation bar. There's no way to check if this option is enabled, and deviceHasKey still returns true for the keys that are disabled by this option.

This is the closest you can get:

boolean hasBackKey = KeyCharacterMap.deviceHasKey(KeyEvent.KEYCODE_BACK);
boolean hasHomeKey = KeyCharacterMap.deviceHasKey(KeyEvent.KEYCODE_HOME);

if (hasBackKey && hasHomeKey) {
    // no navigation bar, unless it is enabled in the settings
} else {
    // 99% sure there's a navigation bar
}

If the back and home button are not both physically present on the device, it must have a navigation bar, because the user otherwise wouldn't be able to navigate at all. However, you can never be 100% sure about this, since manufacturers can implement deviceHasKey wrong.

回答3:

Another solution (a part of my class UtilsUISystem )

    public static boolean hasNavBar (Resources resources)
    {
        //Emulator
        if (Build.FINGERPRINT.startsWith("generic"))
            return true;

        int id = resources.getIdentifier("config_showNavigationBar", "bool", "android");
        return id > 0 && resources.getBoolean(id);
    }

回答4:

Here is a quick answer that combines Pauland's and Philask's solutions. I'm afraid I don't have enough devices available to test if it works everywhere, though. I'd be interested to hear others' results.

boolean hasNavBar(Context context) {
    Resources resources = context.getResources();
    int id = resources.getIdentifier("config_showNavigationBar", "bool", "android");
    if (id > 0) {
        return resources.getBoolean(id);
    } else {    // Check for keys
        boolean hasMenuKey = ViewConfiguration.get(context).hasPermanentMenuKey();
        boolean hasBackKey = KeyCharacterMap.deviceHasKey(KeyEvent.KEYCODE_BACK);
        return !hasMenuKey && !hasBackKey;
    }
}

回答5:

you could add this code to your activity's onCreate() method:

 View decorView = getWindow().getDecorView();
decorView.setOnSystemUiVisibilityChangeListener
        (new View.OnSystemUiVisibilityChangeListener() {
            @Override
            public void onSystemUiVisibilityChange(int visibility) {
                if ((visibility & View.SYSTEM_UI_FLAG_HIDE_NAVIGATION) == 0) {
                    // TODO: The navigation bar is visible. Make any desired
                    // adjustments to your UI, such as showing the action bar or
                    // other navigational controls.
                } else {
                    // TODO: The navigation bar is NOT visible. Make any desired
                    // adjustments to your UI, such as hiding the action bar or
                    // other navigational controls.
                }
            }
        });

回答6:

This method worked for me

    int id = getResources().getIdentifier("config_showNavigationBar","bool","android");
        boolean result = id > 0 && getResources().getBoolean(id);
//
        if(result) {

            // Do whatever you need to do, this device has a soft Navigation Bar
        }

It worked for me and tested in many devices.

回答7:

Something that should probably work better is to measure the screen.

Starting with API 17 there's getWindowManager().getDefaultDisplay().getRealSize(), which can be compared to size returned by getWindowManager().getDefaultDisplay().getSize().

If you get different results I think it's safe to say that there is a nav bar and if you get the same results there isn't one. One thing to pay attention to is your target SDK and supported screens, which might cause the result of getSize() to be scaled if Android thinks your app wouldn't work well on the current device without scaling.

Below API 17 you can measure the screen via getWindowManager().getDefaultDisplay().getMetrics() in both landscape and portrait mode, and again, different results probably mean there's a nav bar.

However, if you get the same results, you don't actually know, as phones can keep the nav bar on the shorter edge even when in landscape. An educated guess would be that if either the width or the height is 4% to 8% smaller than standard sizes like 1280x800, 1280x720, 1024x600, while the other dimension is equal, then again there probably is a nav bar. Don't bet on it, though. There are too many resolutions, which differ too little from one another for this to work well.

回答8:

boolean hasNavBar(Context context) {
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
        // navigation bar was introduced in Android 4.0 (API level 14)
        Resources resources = context.getResources();
        int id = resources.getIdentifier("config_showNavigationBar", "bool", "android");
        if (id > 0) {
            return resources.getBoolean(id);
        } else {    // Check for keys
            boolean hasMenuKey = ViewConfiguration.get(context).hasPermanentMenuKey();
            boolean hasBackKey = KeyCharacterMap.deviceHasKey(KeyEvent.KEYCODE_BACK);
            return !hasMenuKey && !hasBackKey;
        }
    } else {
        return false;
    }
}

回答9:

I see the answers above, I want to indicate that the "not exist" can be regard as the height of 0; so it can be like this:

public static int getScreenH(Context context) {
    DisplayMetrics dm = new DisplayMetrics();
    dm = context.getResources().getDisplayMetrics();
    int h = dm.heightPixels;
    return h;
}

public static int getDpi(Context context) {

    DisplayMetrics displayMetrics1 = context.getResources().getDisplayMetrics();
    int height1 = displayMetrics1.heightPixels;

    int dpi = 0;
    WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    Display display = windowManager.getDefaultDisplay();
    DisplayMetrics displayMetrics = new DisplayMetrics();

    @SuppressWarnings("rawtypes")
    Class c;
    try {
        c = Class.forName("android.view.Display");
        @SuppressWarnings("unchecked")
        Method method = c.getMethod("getRealMetrics", DisplayMetrics.class);
        method.invoke(display, displayMetrics);
        dpi = displayMetrics.heightPixels;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return dpi;
}

public static int getBottomStatusHeight(Context context) {
    int totalHeight = getDpi(context);

    int contentHeight = getScreenH(context);

    return totalHeight - contentHeight;
}

```

回答10:

Solution: Only devices without permanent hardware keys have the navigation bar hence you can check for the API version and use hasPermanentMenuKey() to find hardware keys

 boolean hasMenuKey = ViewConfiguration.get(context).hasPermanentMenuKey();

来源：https://stackoverflow.com/questions/16092431/check-for-navigation-bar