Implement `FromJava` for `Option<T>`

1 files changed, 21 insertions, 1 deletions

diff --git a/mullvad-jni/src/from_java.rs b/mullvad-jni/src/from_java.rs
index 526a83e1fb..11b98ad753 100644
--- a/mullvad-jni/src/from_java.rs
+++ b/mullvad-jni/src/from_java.rs
@@ -1,4 +1,8 @@
-use jni::{objects::JString, JNIEnv};
+use jni::{
+    objects::{JObject, JString},
+    JNIEnv,
+};
+use std::ops::Deref;
 
 pub trait FromJava<'env> {
     type JavaType: 'env;
@@ -6,6 +10,22 @@ pub trait FromJava<'env> {
     fn from_java(env: &JNIEnv<'env>, source: Self::JavaType) -> Self;
 }
 
+impl<'env, T> FromJava<'env> for Option<T>
+where
+    T: FromJava<'env>,
+    T::JavaType: Deref<Target = JObject<'env>>,
+{
+    type JavaType = T::JavaType;
+
+    fn from_java(env: &JNIEnv<'env>, source: Self::JavaType) -> Self {
+        if source.is_null() {
+            None
+        } else {
+            Some(T::from_java(env, source))
+        }
+    }
+}
+
 impl<'env> FromJava<'env> for String {
     type JavaType = JString<'env>;