Introduction to lambda expressions

• Introduced in JDK 8.

• Increased the power of expression of the Java language.

• Added new syntax elements and optimized common structures.

• Comparison: Just as generics reshaped Java in the past, lambda expressions are reshaping it today.

• Lambda expressions introduce a more concise and expressive style of programming.

• Promote more functional programming.

Lambda Expression:

• Anonymous method (without name).

• It is not executed in isolation; implements methods of a functional interface.

• Equivalent to a form of anonymous class.

• Lambdas also known as closures (capture variables from their scope).

Functional Interface:

• Contains only one abstract method.

• Represents a single action or purpose.

• Example: Runnable with the run() method.

• Defines the target type of a lambda expression.

• Also called SAM (Single Abstract Method) type.

Rules and Observations

• A lambda expression can only be used in contexts with a specified target type.

• The target type is the expected type of the lambda expression, and it needs to be compatible with the type of the abstract method of the functional interface

• Functional interfaces can include public Object methods (such as equals()) without losing their functional interface status. These methods are considered implicitly implemented.

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