JDK8代码实践，简单易懂

package com.test.jdk8; import java.util.function.*; public class FunctionalInterfaceTest { public static void main(String[] args) { testFunctionInterface(); testOperationFnInterface(); } private static void testFunctionInterface() { System.out.println("自带的函数式接口"); //Consumer<T> - T作为输入，执行某种动作但没有返回值 Consumer<String> con = (x) -> { System.out.println(x); }; con.accept("hello world"); //Supplier<T> - 没有任何输入，返回T Supplier<String> supp = () -> { return "Supplier"; }; System.out.println(supp.get()); //Predicate<T> -T作为输入，返回的boolean值作为输出 Predicate<String> pre = (x) -> { System.out.print(x); return x.startsWith("op"); }; System.out.println(": " + pre.test("op, hello World")); // Function<T, R> -T作为输入，返回的R作为输出 Function<String, String> function = (x) -> { System.out.print(x + ": "); return "Function"; }; System.out.println(function.apply("hello world")); //BinaryOperator<T> -两个T作为输入，返回一个T作为输出，对于“reduce”操作很有用 BinaryOperator<String> bina = (x, y) -> { System.out.print(x + " " + y); return "BinaryOperator"; }; System.out.println(" " + bina.apply("hello ", "world")); System.out.println(); } private static void testOperationFnInterface() { System.out.println("使用CalcInterface"); CalcInterface<Integer, Integer> addOper1 = (n1, n2) -> { return n1 + n2; }; CalcInterface<Integer, Integer> multiOper1 = (n1, n2) -> { return n1 * n2; }; NumberOperation<Integer, Integer> np = new NumberOperation(13, 10); System.out.println(np.calc1(addOper1)); System.out.println(np.calc1(multiOper1)); System.out.println(np.calc1((n1, n2) -> n1 + n2)); System.out.println(np.calc1((n1, n2) -> n1 * n2)); System.out.println(); System.out.println("使用BinaryOperator"); BinaryOperator<Integer> addOper2 = (n1, n2) -> { return n1 + n2; }; BinaryOperator<Integer> multiOper2 = (n1, n2) -> { return n1 * n2; }; System.out.println(np.calc2(addOper2)); System.out.println(np.calc2(multiOper2)); } @FunctionalInterface public interface CalcInterface<N, V> { V operation(N n1, N n2); } public static class NumberOperation<N extends Number, V extends Number> { private N n1; private N n2; public NumberOperation(N n1, N n2) { this.n1 = n1; this.n2 = n2; } public V calc1(CalcInterface<N, V> ci) { V v = ci.operation(n1, n2); return v; } public N calc2(BinaryOperator<N> ci) { N v = ci.apply(n1, n2); return v; } } }