java arrow function with code examples

Java Arrow Function with Code Examples

Java 8 introduced a new feature called "Lambda expressions". A lambda expression is a block of code that can be passed around as an object. Along with lambda expressions, Java 8 also introduced the arrow function, which is a shorthand syntax for writing lambda expressions. Arrow functions enable developers to write more concise and readable code.

What is an Arrow Function?

An arrow function is a shorthand syntax for writing lambda expressions in Java. Instead of using the traditional "lambda" keyword and brackets, an arrow function uses "->" instead. Here is a simple example:

public interface MyInterface {
    int func(int x, int y);
}

public class MyClass {
    public static void main(String[] args) {
        MyInterface add = (x, y) -> x + y;
        System.out.println(add.func(4, 5));
    }
}

In the above code, we have defined an interface "MyInterface" that defines a single method called "func". We then create a new instance of the interface using an arrow function and assign it to a variable "add". The arrow function takes two arguments "x" and "y" and returns the sum of the two.

How does it Work?

The arrow function syntax is as follows:

(parameter list) -> expression

The "parameter list" is a comma-separated list of zero or more parameters that the arrow function takes. The "expression" is the code that is executed when the arrow function is called.

Here is another example:

public interface Greeting {
    String sayHello(String name);
}

public class MyClass {
    public static void main(String[] args) {
        Greeting greet = name -> "Hello " + name;
        System.out.println(greet.sayHello("World"));
    }
}

In the above code, we have defined an interface "Greeting" that defines a single method called "sayHello". We then create a new instance of the interface using an arrow function and assign it to a variable "greet". The arrow function takes a single argument "name" and returns a string "Hello" followed by the name.

Arrow Functions with Optional Braces

An arrow function can have an optional set of braces around the expression. This is useful when the expression is more than one line. Here is an example:

public interface MyInterface {
    void func();
}

public class MyClass {
    public static void main(String[] args) {
        MyInterface printHello = () -> {
            System.out.println("Hello");
            System.out.println("World");
        };
        printHello.func();
    }
}

In the above code, we define an interface "MyInterface" that defines a single method called "func". We then create a new instance of the interface using an arrow function and assign it to a variable "printHello". The arrow function takes no arguments and prints "Hello" and "World" to the console.

Arrow Functions with Multiple Arguments

An arrow function can take multiple arguments by separating them with commas in the parameter list. Here is an example:

public interface MathCalculation {
    int calculate(int x, int y);
}

public class MyClass {
    public static void main(String[] args) {
        MathCalculation add = (x, y) -> x + y;
        MathCalculation subtract = (x, y) -> x - y;
        System.out.println(add.calculate(4, 5));
        System.out.println(subtract.calculate(4, 5));
    }
}

In the above code, we define an interface "MathCalculation" that defines a single method called "calculate". We then create two new instances of the interface using arrow functions – "add" and "subtract". The arrow functions take two arguments "x" and "y" and return the sum and difference of the two, respectively.

Conclusion

Arrow functions in Java are a shorthand syntax for writing lambda expressions. They enable developers to write more concise and readable code. Arrow functions can have optional braces, take multiple arguments, and be used with interfaces to create new instances. Overall, arrow functions in Java are a powerful feature that can help developers write more efficient and maintainable code.

let's dive deeper into the previous topics.

Lambda expressions:

Lambda expressions are a feature introduced in Java 8 that allow us to pass around blocks of code as objects. It's a technique borrowed from functional programming, where functions are first-class citizens. A lambda expression is an anonymous function that doesn't have a name, but does have parameters, a body, and a return type.

Here is an example of a lambda expression:

() -> System.out.println("Hello World");

This lambda expression takes no arguments, has an empty body, and returns void.

Lambda expressions can also be used with parameters, like this:

(s) -> s.length();

This lambda expression takes a single parameter of type String, then returns the length of that string.

Arrow Functions:

Arrow functions are a shorthand syntax for lambda expressions in Java. Arrow functions use -> instead of the traditional lambda keyword and brackets. Arrow functions allow for more concise and readable code.

Here is an example of an arrow function:

(x, y) -> x + y;

This arrow function takes two parameters, x and y, and returns their sum.

Arrow functions can also be used with interfaces to create instances of those interfaces, like this:

Greeting greet = name -> "Hello " + name;

This arrow function takes a single parameter of type String, then returns the string "Hello" followed by the passed-in name.

Optional Braces:

Arrow functions can use optional braces around the block of code that makes up the function body. This is useful when the expression is more than one line or when we want to improve readability.

Here is an example of an arrow function with optional braces:

() -> {
    System.out.println("Hello");
    System.out.println("World");
};

This arrow function takes no parameters, but its body consists of two lines of code. The braces make it more readable.

Multiple Arguments:

Arrow functions can also take multiple arguments by separating them with commas in the parameter list.

Here is an example of an arrow function with multiple arguments:

(x, y) -> x - y;

This arrow function takes two parameters, x and y, and returns their difference.

In conclusion, lambda expressions and arrow functions are powerful features that allow us to write more concise and readable code in Java. Understanding these concepts will help you to write more efficient and maintainable code.

java arrow function with code examples

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