Java Tutorials

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Java Functional Interfaces

    Java 8 introduced Lambda Expressions, These expressions depends on Functional Interfaces. A Functional Interface is an Interface which has only one Abstract method, and also it can have static and default methods. It can optionally be decorated with @FunctionalInterface Annotation.

Earlier java(i.e before JDK8) , an interfaces can be implemented using class/anonymous class. An anonymous class is a class which has no class name, and can implement interface methods.

Functional interfaces can be used as a return type for lambda expressions and method references.

Java 8 Consumer Interfaces takes generic argument and returns nothing.

Java Framework Built-in Consumer Functional Interfaces.

• IntConsumer
• LongConsumer
• DoubleConsumer

Consumer Interfaces
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Consumer
BiConsumer
ObjIntConsumer
ObjLongConsumer
ObjDoubleConsumer