lambda 是 java 8 引入的新特性,lambda 能替换简单的函数和类,简化了代码,提升了代码可读性java
(Type1 param1, Type2 param2, ...) -> { statement1; statement2; ... return statementX; }
java 里面没有函数对象,因此提供了不少只有一个方法的接口,这类接口被称为函数式接口,这些接口能够用 lambda 表达式来构造git
Predicate<Integer> greater10 = x -> x > 10; Consumer<Integer> print = x -> System.out.println(x); Function<Integer, String> intToString = x -> Integer.valueOf(x).toString(); Supplier<Integer> randInt = () -> ThreadLocalRandom.current().nextInt(); Comparator<Integer> less = (x, y) -> y - x; UnaryOperator<Integer> power = x -> x * x; BinaryOperator<Integer> add = (x, y) -> x + y; BiConsumer<Integer, String> printis = (i, s) -> System.out.println(i + s); Runnable run = () -> System.out.println("hello world");
lambda 表达式能够直接引用类或者对象的方法,语法: <object|class>::method
github
也能够用 <class>::new
引用无参构造函数,带参构造函数能够用上面的 lambda 语法构造less
Consumer<Integer> print = System.out::println; Predicate<String> empty = String::isEmpty; Supplier<Date> date = Date::new;