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A java.util.function.Function
is a Java 8 functional interface whose sole purpose is to return any result
by working on a single input argument. It accepts an argument of type T
and returns a result of type
R
, by applying specified logic on the input via the apply
method. The
interface definition shown here:
package java.util.function; @FunctionalInterface public interface Function<T extends Object, R extends Object> { public R apply(T t); ... }
A Function
interface is used in cases when you want to encapsulate some code into a method which accepts some value as
an input parameter and then returns another value after performing required operations on the input. The input parameter type and
the return type of the method can either be same or different:
Function<String, Boolean> f = s -> new Boolean(s); System.out.println(f.apply("TRUE")); System.out.println(f.apply("true")); System.out.println(f.apply("Java8")); System.out.println(f.apply(null));
Output:
true true false false
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