https://github.com/noties/listeners

Simple data structure with iteration and adding/removal of elements without copying of underlying collection
https://github.com/noties/listeners

android ui-listeners

Last synced: about 2 months ago
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Simple data structure with iteration and adding/removal of elements without copying of underlying collection

• Host: GitHub
• URL: https://github.com/noties/listeners
• Owner: noties
• License: apache-2.0
• Created: 2017-12-20T14:11:46.000Z (about 7 years ago)
• Default Branch: master
• Last Pushed: 2018-01-13T18:22:38.000Z (almost 7 years ago)
• Last Synced: 2023-07-07T14:17:23.018Z (over 1 year ago)
• Topics: android, ui-listeners
• Language: Java
• Homepage:
• Size: 62.5 KB
• Stars: 1
• Watchers: 3
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Listeners<T>

[![listeners](https://img.shields.io/maven-central/v/ru.noties/listeners.svg?label=listeners)](http://search.maven.org/#search|ga|1|g%3A%22ru.noties%22%20AND%20a%3A%22listeners%22)

Simple data structure for listeners and observers that allows adding/removing elements whilst iterating without copying underlying collection. Aimed for use in one thread (for example some UI events listeners)

```java

interface MyListener {

    void apply(@NonNull MyListenersStore store);

}

```

```java

class MyListenersStore {

    private final Listeners listeners = Listeners.create();

    void register(@NonNull MyListener listener) {

        listeners.add(listener);

    }

    void unregister(@NonNull MyListener listener) {

        listeners.remove(listener);

    }

    void notifyListeners() {

        for (MyListener listener : listeners.begin()) {

            listener.apply(this);

        }

    }

}

```

Then, `MyListener` can be implemented like this:

```java

class MyListenerImpl implements MyListener {

    @Override

    public void apply(@NonNull MyListenersStore store) {

        // do something here

        doSomething();

        // and unregister

        store.unregister(this);

    }

}

```

### Limitations

Only one iteration can happen at a time

```java

for (MyListener listener1 : listeners.begin()) {

    for (MyListener listener2 : listeners.begin()) { // will throw

    }

}

```

The same if listener itself triggers notification:

```java

class MyListenerImpl implements MyListener {

    @Override

    public void apply(@NonNull MyListenersStore store) {

        store.notifyListeners(); // will throw

    }

}

```

If you plan to iterate on part of collection (for example with early break or some condition), explicit `end()` must be called.

```java

for (MyListener listener : listeners.begin()) {

    if (!isValid()) {

        break;

    }

}

listeners.end();

```

## License

```

  Copyright 2017 Dimitry Ivanov ([email protected])

  Licensed under the Apache License, Version 2.0 (the "License");

  you may not use this file except in compliance with the License.

  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software

  distributed under the License is distributed on an "AS IS" BASIS,

  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  See the License for the specific language governing permissions and

  limitations under the License.

```