What is -> in Java?

What is -> in Java?

I'd be happy to explain what => is in Java.

In programming, => is an operator that means "returns". It's used to indicate the return type of a method or a value returned by a function. For example:

public int add(int a, int b) {
return a + b;
}

In this case, add() returns an integer, which can be represented as int => int where "int" is the return type.

In functional programming, => is used as an arrow operator to separate the input from the output. For instance:

Function func = (s) => s.length();

Here, func is a function that takes a string and returns its length. The (s) => s.length() part is saying "given an input s, return its length".

In lambda expressions, => is used to define anonymous functions. For example:

List list = Arrays.asList("apple", "banana");
list.sort((a, b) => a.compareTo(b));

Here, the lambda expression (a, b) => a.compareTo(b) defines an anonymous function that takes two strings and compares them lexicographically.

In Java 8, => is used in method references, which allow you to refer to existing methods as if they were lambda expressions. For example:

List list = Arrays.asList("apple", "banana");
list.sort(String::compareTo);

Here, the String::compareTo expression refers to the compareTo() method of the String class.

In summary, => is a powerful operator in Java that allows you to define functions, methods, and lambda expressions. It's used extensively in functional programming and data processing, making your code more concise and expressive.

What is -> in Java?

I'm happy to respond in English!

The -> symbol in Java is known as the "arrow operator" or "lambda arrow". It's used to declare a lambda expression, which is a shorthand way to create an anonymous function (also known as a closure) that can be executed later.

The -> symbol is often read as "goes to" or "maps to", indicating that the value on the left side of the operator will be transformed into the value on the right side. In other words, it's like saying: "take this thing, and transform it into that thing".

Here's a simple example:

String[] strings = {"hello", "world", "lambda"};
List upperCaseStrings = Arrays.stream(strings)
.map(s -> s.toUpperCase())
.collect(Collectors.toList());

In this code, we're using the map method to transform each string in the strings array into uppercase. The lambda expression (s -> s.toUpperCase()) is executed for each string, and the result is collected into a new list.

Lambda expressions are often used with functional programming APIs like Java 8's Stream API, which provides a way to process streams of data in a declarative manner (i.e., without explicitly writing loops). Lambda expressions can also be used as method arguments or as event handlers.

Here's another example:

Button button = new Button("Click me!");
button.setOnAction(event -> System.out.println("Button clicked!"));

In this code, we're using a lambda expression to handle the onAction event of a Button. When the button is clicked, the lambda expression will execute and print "Button clicked!" to the console.

The arrow operator has many uses in Java, including:

Overall, the -> symbol is a powerful and concise way to express functional programming concepts in Java!