# JNI Zero Refactoring Examples

## 1. Instance Methods

**Before:**

```cpp
void TokenAndroid::FromJavaToken(JNIEnv* env, const JavaRef<jobject>& j_token) {
  uint64_t high = Java_TokenBase_getHighForSerialization(env, j_token);
}
```

**After:**

```cpp
// In .h
static base::Token FromJavaToken(JNIEnv* env, const JavaRef<JTokenBase>& j_token);

// In .cc
...
base::Token TokenAndroid::FromJavaToken(JNIEnv* env, const JavaRef<JTokenBase>& j_token) {
  uint64_t high = static_cast<uint64_t>(j_token->getHighForSerialization(env));
}
```

## 2. Static Methods

**Before:**

```cpp
void ApplicationStatusListener::NotifyApplicationStateChange(ApplicationState state) {
  Java_ApplicationStatus_registerThreadSafeNativeApplicationStateListener(AttachCurrentThread());
}
```

**After:**

```cpp
// In .cc
...
void ApplicationStatusListener::NotifyApplicationStateChange(ApplicationState state) {
  JApplicationStatusClass::registerThreadSafeNativeApplicationStateListener(AttachCurrentThread());
}
```

## 3. System Classes (e.g., ParcelFileDescriptor)

**Before:**

```cpp
int ContentUriGetFd(const JavaRef<jobject>& java_parcel_file_descriptor) {
  int fd = Java_ContentUriUtils_getFd(env, java_parcel_file_descriptor);
}
```

**After:**

```cpp
// In .cc
...
int ContentUriGetFd(const JavaRef<jobject>& java_parcel_file_descriptor) {
  int fd = JContentUriUtilsClass::getFd(env, java_parcel_file_descriptor);
}
```

## 4. Converting ScopedJavaLocalRef<jobject>()

**Before:**

```cpp
return ScopedJavaLocalRef<jobject>();
```

**After:**

```cpp
return nullptr;
```

## 5. Arrays

### Creating Object Arrays

**Before:**

```cpp
jobjectArray j_strs = env->NewObjectArray(size, string_clazz, nullptr);
```

**After:**

```cpp
ScopedJavaLocalRef<JArray<jstring>> strs = NewStringArray(env, size);
```

### Accessing Elements

**Before:**

```cpp
jobject j_obj = env->GetObjectArrayElement(j_array, index);
ScopedJavaLocalRef<MyClass> obj = AdoptRef(env, static_cast<MyClass>(j_obj));

jstring j_str = static_cast<jstring>(env->GetObjectArrayElement(j_strs, index));
std::string str = ConvertJavaStringToUTF8(env, j_str);
```

**After:**

```cpp
ScopedJavaLocalRef<JMyClass> obj = array.Get(env, index);

std::string str = strs.GetAs<std::string>(env, index);
```

### Setting Elements

**Before:**

```cpp
env->SetObjectArrayElement(j_array, index, value.obj());
```

**After:**

```cpp
array.Set(env, index, value);
```

### Iterating Arrays

**Before:**

```cpp
jsize length = env->GetArrayLength(j_array);
for (jsize i = 0; i < length; ++i) {
  ScopedJavaLocalRef<jstring> j_str = AdoptRef(env, static_cast<jstring>(env->GetObjectArrayElement(j_array, i)));
  std::string str = ConvertJavaStringToUTF8(env, j_str);
  // ...
}
```

**After:**

```cpp
for (auto str : strs.CreateView(env)) {
  std::string s = str.ConvertTo<std::string>(env);
  // ...
}
```

### Primitive Arrays

**Before:**

```cpp
jbyteArray j_array = ...;
jbyte* bytes = env->GetByteArrayElements(j_array, nullptr);
jsize length = env->GetArrayLength(j_array);
std::string_view sv(reinterpret_cast<char*>(bytes), length);
// ...
env->ReleaseByteArrayElements(j_array, bytes, JNI_ABORT);
```

**After:**

```cpp
ScopedJavaLocalRef<JArray<int8_t>> array = ...;
JArrayViewCritical<int8_t> array_view = array.CreateViewCritical(env);
std::string_view sv = array_view.as_string_view();
```

*(Note: `JArrayViewCritical` automatically releases the elements when it goes
out of scope.)*