Lecture 80:-  Lambda Expressions Syntax

The syntax of lambda expressions in Java is as follows:

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(parameters) -> expression or statement block

Here's a breakdown of the components:

1. Parameters:
   • The parameters are a comma-separated list of formal parameters enclosed in parentheses ( ). If the lambda takes no parameters, you can leave the parentheses empty. If there is only one parameter, you can omit the parentheses. For multiple parameters, separate them with commas.
   • Example with no parameters: () -> expression
   • Example with one parameter: (int x) -> expression
   • Example with multiple parameters: (int x, int y) -> expression
2. Arrow Operator:
   • The arrow operator -> separates the parameters from the body of the lambda expression.
   • It indicates that the parameters are being passed to the body of the lambda expression.
   • Example: (x, y) -> expression
3. Expression or Statement Block:
   • The body of the lambda expression can be either a single expression or a block of multiple statements.
   • If the body is a single expression, you can omit the curly braces { }.
   • If the body is a block of statements, you need to enclose them in curly braces { }.
   • If the body is a block, you may need to include a return statement explicitly to return a value.
   • Examples:
     • Single expression: (x, y) -> x + y
     • Statement block: (x, y) -> { int sum = x + y; return sum; }

Here are some more examples of lambda expressions with different syntax:

1. Lambda expression with no parameters and a single expression:

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   () -> "Hello, World!"

2. Lambda expression with one parameter and a single expression:

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   (String name) -> "Hello, " + name

3. Lambda expression with two parameters and a statement block:

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   (int a, int b) -> {    int sum = a + b;    return sum; }

4. Lambda expression with no parameters and a statement block:

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   () -> {    System.out.println("This is a lambda expression."); }

5. Lambda expression with a functional interface:

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   Predicate<Integer> isEven = (n) -> n % 2 == 0;

Lambda expressions are used to provide a concise implementation of functional interfaces and are widely used in Java 8 and later versions to simplify functional programming and functional-style operations on collections and streams.