Android Annotation

dependency:

dependencies {
    // If you stay on Support Library
    implementation 'com.android.support:support-annotations:28.0.0'    // If you use AndroidX
    implementation 'androidx.annotation:annotation:1.0.1'
}

限定參數型別，類似防呆的做法，像是

private void showToast(Context context, @StringRes strMsg)
{
    Toast.makeText(context, strMsg, Toast.LENGTH_SHORT).show();
}

或是Java與kotlin協作的時候可以用到non-null的判斷

private void showMsg(@NonNull SimpleObj obj)
{
        ...
}

數字範圍判斷：IntRange/FloatRange

public void count(@IntRange(from = 1, to = 100) int times)
{

}

IdRes/LayoutRes/DrawableRes/...[Any]Res

要求某權限：ex.@RequirePermission(Manifest.permission.ACCESS_FINE_LOCATION)