Struct jni::objects::JList

pub struct JList<'local, 'other_local_1: 'obj_ref, 'obj_ref> { /* private fields */ }

Wrapper for JObjects that implement java/util/List. Provides methods to get, add, and remove elements.

Looks up the class and method ids on creation rather than for every method call.

Implementations

impl<'local, 'other_local_1: 'obj_ref, 'obj_ref> JList<'local, 'other_local_1, 'obj_ref>

pub fn from_env( env: &mut JNIEnv<'local>, obj: &'obj_ref JObject<'other_local_1> ) -> Result<JList<'local, 'other_local_1, 'obj_ref>>

Create a map from the environment and an object. This looks up the necessary class and method ids to call all of the methods on it so that exra work doesn’t need to be done on every method call.

pub fn get<'other_local_2>( &self, env: &mut JNIEnv<'other_local_2>, idx: jint ) -> Result<Option<JObject<'other_local_2>>>

Look up the value for a key. Returns Some if it’s found and None if a null pointer would be returned.

pub fn add(&self, env: &mut JNIEnv<'_>, value: &JObject<'_>) -> Result<()>

Append an element to the list

pub fn insert( &self, env: &mut JNIEnv<'_>, idx: jint, value: &JObject<'_> ) -> Result<()>

Insert an element at a specific index

pub fn remove<'other_local_2>( &self, env: &mut JNIEnv<'other_local_2>, idx: jint ) -> Result<Option<JObject<'other_local_2>>>

Remove an element from the list by index

pub fn size(&self, env: &mut JNIEnv<'_>) -> Result<jint>

Get the size of the list

pub fn pop<'other_local_2>( &self, env: &mut JNIEnv<'other_local_2> ) -> Result<Option<JObject<'other_local_2>>>

Pop the last element from the list

Note that this calls size() to determine the last index.

pub fn iter<'list>( &'list self, env: &mut JNIEnv<'_> ) -> Result<JListIter<'list, 'local, 'obj_ref, 'other_local_1>>

Get key/value iterator for the map. This is done by getting the EntrySet from java and iterating over it.

The returned iterator does not implement std::iter::Iterator and cannot be used with a for loop. This is because its next method uses a &mut JNIEnv to call the Java iterator. Use a while let loop instead:

let mut iterator = list.iter(env)?;

while let Some(obj) = iterator.next(env)? {
    let obj: AutoLocal<JObject> = env.auto_local(obj);

    // Do something with `obj` here.
}

Each call to next creates a new local reference. To prevent excessive memory usage or overflow error, the local reference should be deleted using JNIEnv::delete_local_ref or JNIEnv::auto_local before the next loop iteration. Alternatively, if the list is known to have a small, predictable size, the loop could be wrapped in JNIEnv::with_local_frame to delete all of the local references at once.

Trait Implementations

impl<'local, 'other_local_1: 'obj_ref, 'obj_ref> AsRef<JList<'local, 'other_local_1, 'obj_ref>> for JList<'local, 'other_local_1, 'obj_ref>

fn as_ref(&self) -> &JList<'local, 'other_local_1, 'obj_ref>

Converts this type into a shared reference of the (usually inferred) input type.

impl<'local, 'other_local_1: 'obj_ref, 'obj_ref> AsRef<JObject<'other_local_1>> for JList<'local, 'other_local_1, 'obj_ref>

fn as_ref(&self) -> &JObject<'other_local_1>

Converts this type into a shared reference of the (usually inferred) input type.