java.util.function.Function is a functional interface as part of java.util.function package which is introduced in Java 8. It is an in-built Functional Interface. This function expects one argument and produces a result. In this post, we are going to see several implementations of Function Interface using different examples.
java.util.function.Function Interface in Java 8 with Examples...!!! Click To TweetLook at java.util.function.Function Javadoc description below:
Function Interface contains 4 methods:
apply
compose
andThen
identity
Lets understand above mentioned methods thorough various examples:
Example 1. ‘apply’ method
Below example shows how to use ‘apply’ method of ‘Function’ interface using Lambda expression.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | import java.util.function.Function; public class FunctionInterfaceJava8Example_with_apply { public static void main(String[] args) { System.out.println("Function Interface - 'apply' example \n"); Function <Integer, Integer> functionObj = i -> i * 2; System.out.println("Double of 5 : " + functionObj.apply(5)); } } |
Output:
1 2 3 | Function Interface - 'apply' example Double of 5 : 10 |
Example 2. ‘andThen’ & ‘compose’ methods
Below example shows how to use ‘andThen’ & ‘compose’ methods of ‘Function’ interface using Lambda expression.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | import java.util.function.Function; public class FunctionInterfaceJava8Example_with_andThen_Compose { public static void main(String[] args) { System.out.println("Function Interface - 'andThen' & 'compose' example \n"); Function <Integer, Integer> functionObj1 = i -> i * 10; Function <Integer, Integer> functionObj2 = i -> i / 2; //andThen operation System.out.println("Result of 'andThen' method: " + functionObj1.andThen(functionObj2).apply(4)); //compose operation System.out.println("Result of 'compose' method: " + functionObj1.compose(functionObj2).apply(4)); } } |
Output:
1 2 3 4 | Function Interface - 'andThen' & 'compose' example Result of 'andThen' method: 20 Result of 'compose' method: 20 |
Do you like this Post? – then check my other helpful posts:
- Passing Function as a Parameter in another Method in Java 8
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