# 函数式接口 ## Java8 函数式接口一览 ~~~ // Function<T, R> -T作为输入，返回的R作为输出 Function<String,String> fun = (x) -> {System.out.print(x+": ");return "Function";}; System.out.println(function.apply("hello world")); //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 false;}; System.out.println(": "+pre.test("hello World")); //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()); //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")); ~~~ ## 自定义函数式 ~~~ @FunctionalInterface ~~~