MissingNullability: android.os.cipher.Xxxx#init(int, Key, int) parameter #1: Missing nullability on parameter `key` in method `init` 需要导包: Framework: import android.annotation.NonNull; import android.annotation.Nullable; Libcore: import android.support.annotation.NonNull; import android.support.annotation.Nullable; 在函数增加注解: public void init(int opmode, @NonNull Key key, int index