Android端末でソフトウェアキーのナビゲーションバーの有無を判定 ref: http://qiita.com/ueno-yuhei/items/4bd7c46bf3665bee0cad

file0.java

ViewConfiguration.get(context).hasPermanentMenuKey()

file1.java

public static boolean hasNavigationBar(Context context) {
    Resources res = context.getResources();
    int resourceId = res.getIdentifier("config_showNavigationBar", "bool", "android");
    if (resourceId != 0) {
        String sNavBarOverride = "";
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
            try {
                Class c = Class.forName("android.os.SystemProperties");
                Method m = c.getDeclaredMethod("get", String.class);
                m.setAccessible(true);
vsNavBarOverride = (String) m.invoke(null, "qemu.hw.mainkeys");
            } catch (Throwable e) {
                e.printStackTrace();
                sNavBarOverride = "";
            }
         }
         boolean hasNav = res.getBoolean(resourceId);
         // check override flag (see static block)
         if ("1".equals(sNavBarOverride))
                hasNav = false;
         else if ("0".equals(sNavBarOverride))
                hasNav = true;
                return hasNav;
         } else { // fallback
                return !ViewConfiguration.get(context).hasPermanentMenuKey();
        }
    }