我检查了我的Android 4.1.2设备上的Locale方法，结果是:

Locale.getDefault().getLanguage()       ---> en      
Locale.getDefault().getISO3Language()   ---> eng 
Locale.getDefault().getCountry()        ---> US 
Locale.getDefault().getISO3Country()    ---> USA 
Locale.getDefault().getDisplayCountry() ---> United States 
Locale.getDefault().getDisplayName()    ---> English (United States) 
Locale.getDefault().toString()          ---> en_US
Locale.getDefault().getDisplayLanguage()---> English
Locale.getDefault().toLanguageTag()     ---> en-US

你可以用这个

boolean isLang = Locale.getDefault().getLanguage().equals("xx");

当“xx”是任何语言代码，如“en”，“fr”，“sp”，“ar”....等等

你可以尝试从系统资源中获取locale:

PackageManager packageManager = context.getPackageManager();
Resources resources = packageManager.getResourcesForApplication("android");
String language = resources.getConfiguration().locale.getLanguage();

再加上约翰·佩尔格里姆的回答

context.getResources().getConfiguration().locale
Locale.getDefault()

是等价的，因为android.text.format.DateFormat类可以互换使用这两者。

private static String zeroPad(int inValue, int inMinDigits) {
    return String.format(Locale.getDefault(), "%0" + inMinDigits + "d", inValue);
}

and

public static boolean is24HourFormat(Context context) {
    String value = Settings.System.getString(context.getContentResolver(),
            Settings.System.TIME_12_24);

    if (value == null) {
        Locale locale = context.getResources().getConfiguration().locale;

    // ... snip the rest ...
}

public class LocalUtils {

    private static final String LANGUAGE_CODE_ENGLISH = "en";


    // returns application language eg: en || fa ...
    public static String getAppLanguage() {
        return Locale.getDefault().getLanguage();
    }

    // returns device language eg: en || fa ...
    public static String getDeviceLanguage() {
        return ConfigurationCompat.getLocales(Resources.getSystem().getConfiguration()).get(0).getLanguage();
    }

    public static boolean isDeviceEnglish() {
        return getDeviceLanguage().equals(new Locale(LANGUAGE_CODE_ENGLISH).getLanguage());
    }

    public static boolean isAppEnglish() {
        return getAppLanguage().equals(new Locale(LANGUAGE_CODE_ENGLISH).getLanguage());
    }


}

Log.i("AppLanguage: ",     LocalUtils.getAppLanguage());
Log.i("DeviceLanguage: ",  LocalUtils.getDeviceLanguage());
Log.i("isDeviceEnglish: ", String.valueOf(LocalUtils.isDeviceEnglish()));
Log.i("isAppEnglish: ",    String.valueOf(LocalUtils.isAppEnglish()));

获取设备语言的正确方法如下:

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
    return context.getResources().getConfiguration().getLocales().get(0);
} else {
    return context.getResources().getConfiguration().locale;
}

希望能有所帮助。