Author: alegru

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class Test { public static void main(String[] args) { List<String> cities = new ArrayList<>(Arrays.asList(“New York”, “Berlin”, “Bangkok”, “London”)); List<String> modifiedList = cities.stream() .map(String::toUpperCase) .collect(Collectors.toList()); modifiedList.forEach(System.out::println); } } Output: NEW YORK BERLIN BANGKOK LONDON List<List<String>> cities = new ArrayList<>(); cities.add(new ArrayList<>(Arrays.asList(“Paris”, “London”))); cities.add(new ArrayList<>(Arrays.asList(“New York”, “Berlin”))); class Test { public static void main(String[] args) { List<List<String>>…

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class Test { public static void main(String[] args) { List<String> cities = new ArrayList<>(Arrays.asList(“New York”, “Paris”, “London”, “Monte Carlo”, “Berlin”)); cities.stream() .map(city -> city.toUpperCase()) .forEach(city -> System.out.println(city)); } } Output: NEW YORK PARIS LONDON MONTE CARLO BERLIN class Test { public static void main(String[] args) { List<String> cities = new ArrayList<>(Arrays.asList(“New York”, “Paris”, “London”, “Monte…

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@FunctionalInterface interface MyInterface { Message send(String message); } class Message { public Message(String message) { System.out.println(message); } } class Test { public static void main(String[] args) { MyInterface myInterface = Message::new; myInterface.send(“Hello!”); } } Output: Hello! class Message { public Message(String message) { System.out.println(message); } public Message(String message1, String message2) { System.out.println(message1 + message2); }…

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@FunctionalInterface interface Drawable { void draw(); } class Test { public void drawCircle() { System.out.println(“Drawing circle…”); } public static void main(String[] args) { Test test = new Test(); Drawable drawable = () -> test.drawCircle(); drawable.draw(); } } Output: Drawing circle… @FunctionalInterface interface Drawable { void draw(); } class Test { public void drawCircle() { System.out.println(“Drawing…

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@FunctionalInterface public interface Supplier<T> { /** * Gets a result. * * @return a result */ T get(); } class Test { public static void main(String[] args) { Supplier<String> supplier = () -> “Java”; System.out.println(supplier.get()); } } Output: Java class User { private String name; private String username; private String membershipType; private String address; public…

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@FunctionalInterface public interface BinaryOperator<T> extends BiFunction<T,T,T> { /** * Returns a {@link BinaryOperator} which returns the lesser of two elements * according to the specified {@code Comparator}. * * @param <T> the type of the input arguments of the comparator * @param comparator a {@code Comparator} for comparing the two values * @return a {@code…

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@FunctionalInterface public interface UnaryOperator<T> extends Function<T, T> { /** * Returns a unary operator that always returns its input argument. * * @param <T> the type of the input and output of the operator * @return a unary operator that always returns its input argument */ static <T> UnaryOperator<T> identity() { return t -> t;…

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@FunctionalInterface public interface BiPredicate<T, U> { /** * Evaluates this predicate on the given arguments. * * @param t the first input argument * @param u the second input argument * @return {@code true} if the input arguments match the predicate, * otherwise {@code false} */ boolean test(T t, U u); /** * Returns a…

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@FunctionalInterface public interface Predicate<T> { /** * Evaluates this predicate on the given argument. * * @param t the input argument * @return {@code true} if the input argument matches the predicate, * otherwise {@code false} */ boolean test(T t); /** * Returns a composed predicate that represents a short-circuiting logical * AND of this…

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@FunctionalInterface public interface BiConsumer<T, U> { /** * Performs this operation on the given arguments. * * @param t the first input argument * @param u the second input argument */ void accept(T t, U u); /** * Returns a composed {@code BiConsumer} that performs, in sequence, this * operation followed by the {@code after}…

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@FunctionalInterface public interface Consumer<T> { /** * Performs this operation on the given argument. * * @param t the input argument */ void accept(T t); /** * Returns a composed {@code Consumer} that performs, in sequence, this * operation followed by the {@code after} operation. If performing either * operation throws an exception, it is…

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Java has evolved over the years to support functional programming, which is a programming paradigm that emphasizes writing code in terms of functions. In Java, functional programming is made possible with the help of functional interfaces, which are interfaces that define a single abstract method. Functional interfaces can be implemented using lambda expressions or method…

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