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darkhyper24darkhyper24
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added bloC design pattern
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‎bloC/Readme.md

Whitespace-only changes.

‎bloC/etc/bloC.png

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‎bloC/etc/bloC.puml

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@startuml
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package com.iluwatar.bloc {
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class State {
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- value : int
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+ State(value : int)
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+ getValue() : int
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}
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interface StateListener<T> {
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+ onStateChange(state : T)
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}
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interface ListenerManager<T> {
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+ addListener(listener : StateListener<T>)
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+ removeListener(listener : StateListener<T>)
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+ getListeners() : List<StateListener<T>>
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}
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class BloC {
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- currentState : State
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- listeners : List<StateListener<State>>
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+ BloC()
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+ addListener(listener : StateListener<State>)
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+ removeListener(listener : StateListener<State>)
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+ getListeners() : List<StateListener<State>>
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- emitState(newState : State)
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+ increment()
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+ decrement()
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}
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class Main {
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+ main(args : String[])
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}
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ListenerManager <|.. BloC
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StateListener <|.. BloC
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BloC o-- State
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BloC *-- StateListener
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}
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@enduml

‎bloC/pom.xml

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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<groupId>com.iluwatar</groupId>
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<artifactId>java-design-patterns</artifactId>
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<version>1.26.0-SNAPSHOT</version>
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</parent>
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<artifactId>bloC</artifactId>
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<properties>
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<maven.compiler.source>17</maven.compiler.source>
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<maven.compiler.target>17</maven.compiler.target>
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<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
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</properties>
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<dependencies>
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<dependency>
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<groupId>org.junit.jupiter</groupId>
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<artifactId>junit-jupiter-api</artifactId>
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<scope>test</scope>
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</dependency>
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</dependencies>
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</project>

‎bloC/src/main/java/com/iluwatar/bloc/Bloc.java

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package com.iluwatar.bloc;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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public class Bloc implements ListenerManager<State> {
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private State currentState;
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private final List<StateListener<State>> listeners = new ArrayList<>();
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public Bloc() {
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this.currentState = new State(0);
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}
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@Override
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public void addListener(StateListener<State> listener) {
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listeners.add(listener);
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listener.onStateChange(currentState);
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}
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@Override
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public void removeListener(StateListener<State> listener) {
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listeners.remove(listener);
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}
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@Override
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public List<StateListener<State>> getListeners() {
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return Collections.unmodifiableList(listeners);
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}
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private void emitState(State newState) {
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currentState = newState;
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for (StateListener<State> listener : listeners) {
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listener.onStateChange(currentState);
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}
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}
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public void increment() {
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emitState(new State(currentState.getValue() + 1));
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}
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public void decrement() {
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emitState(new State(currentState.getValue() - 1));
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}
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}
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‎bloC/src/main/java/com/iluwatar/bloc/ListenerManager.java

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package com.iluwatar.bloc;
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import java.util.List;
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public interface ListenerManager<T> {
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void addListener(StateListener<T> listener);
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void removeListener(StateListener<T> listener);
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List<StateListener<T>> getListeners();
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}
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‎bloC/src/main/java/com/iluwatar/bloc/Main.java

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package com.iluwatar.bloc;
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import javax.swing.*;
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import java.awt.*;
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public class Main
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{
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public static void main(String[] args)
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{
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Bloc bloC = new Bloc();
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JFrame frame = new JFrame("BloC example");
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frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
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frame.setSize(400, 300);
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JLabel counterLabel = new JLabel("Counter: 0", SwingConstants.CENTER);
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counterLabel.setFont(new Font("Arial", Font.BOLD, 20));
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JButton incrementButton = new JButton("Increment");
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JButton decrementButton = new JButton("Decrement");
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JButton toggleListenerButton = new JButton("Disable Listener");
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frame.setLayout(new BorderLayout());
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frame.add(counterLabel, BorderLayout.CENTER);
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frame.add(incrementButton, BorderLayout.NORTH);
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frame.add(decrementButton, BorderLayout.SOUTH);
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frame.add(toggleListenerButton, BorderLayout.EAST);
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StateListener<State> stateListener = state -> counterLabel.setText("Counter: " + state.getValue());
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bloC.addListener(stateListener);
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toggleListenerButton.addActionListener(e ->
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{
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if (bloC.getListeners().contains(stateListener))
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{
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bloC.removeListener(stateListener);
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toggleListenerButton.setText("Enable Listener");
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} else
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{
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bloC.addListener(stateListener);
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toggleListenerButton.setText("Disable Listener");
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}
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}
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);
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incrementButton.addActionListener(e -> bloC.increment());
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decrementButton.addActionListener(e -> bloC.decrement());
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frame.setVisible(true);
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}
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}

‎bloC/src/main/java/com/iluwatar/bloc/State.java

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package com.iluwatar.bloc;
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public class State
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{
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private final int value;
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public State(int value)
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{
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this.value = value;
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}
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public int getValue()
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{
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return value;
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}
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}

‎bloC/src/main/java/com/iluwatar/bloc/StateListener.java

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package com.iluwatar.bloc;
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public interface StateListener<T>
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{
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void onStateChange(T state);
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}

‎bloC/src/test/java/com/iluwatar/bloc/BlocTest.java

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package com.iluwatar.bloc;
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import org.junit.jupiter.api.BeforeEach;
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import org.junit.jupiter.api.Test;
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import java.util.concurrent.atomic.AtomicInteger;
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import static org.junit.jupiter.api.Assertions.*;
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class BlocTest {
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private Bloc bloc;
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private AtomicInteger stateValue;
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@BeforeEach
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void setUp() {
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bloc = new Bloc();
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stateValue = new AtomicInteger(0);
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}
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@Test
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void initialState() {
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assertTrue(bloc.getListeners().isEmpty(), "No listeners should be present initially.");
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}
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@Test
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void IncrementUpdateState() {
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bloc.addListener(state -> stateValue.set(state.getValue()));
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bloc.increment();
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assertEquals(1, stateValue.get(), "State should increment to 1");
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}
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@Test
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void DecrementUpdateState() {
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bloc.addListener(state -> stateValue.set(state.getValue()));
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bloc.decrement();
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assertEquals(-1, stateValue.get(), "State should decrement to -1");
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}
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@Test
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void addingListener() {
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bloc.addListener(state -> {});
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assertEquals(1, bloc.getListeners().size(), "Listener count should be 1.");
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}
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@Test
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void removingListener() {
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StateListener<State> listener = state -> {};
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bloc.addListener(listener);
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bloc.removeListener(listener);
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assertTrue(bloc.getListeners().isEmpty(), "Listener count should be 0 after removal.");
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}
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@Test
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void multipleListeners() {
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AtomicInteger secondValue = new AtomicInteger();
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bloc.addListener(state -> stateValue.set(state.getValue()));
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bloc.addListener(state -> secondValue.set(state.getValue()));
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bloc.increment();
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assertEquals(1, stateValue.get(), "First listener should receive state 1.");
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assertEquals(1, secondValue.get(), "Second listener should receive state 1.");
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}
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}

‎pom.xml

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<module>function-composition</module>
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<module>microservices-distributed-tracing</module>
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<module>microservices-idempotent-consumer</module>
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<module>bloC</module>
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</modules>
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<repositories>
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<repository>

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