lambda表達(dá)式.png
Lambda 表達(dá)式的簡(jiǎn)單例子:
// 1. 不需要參數(shù),返回值為 5
() -> 5
// 2. 接收一個(gè)參數(shù)(數(shù)字類型),返回其2倍的值
x -> 2 * x
// 3. 接受2個(gè)參數(shù)(數(shù)字),并返回他們的差值
(x, y) -> x – y
// 4. 接收2個(gè)int型整數(shù),返回他們的和
(int x, int y) -> x + y
// 5. 接受一個(gè) string 對(duì)象,并在控制臺(tái)打印,不返回任何值(看起來(lái)像是返回void)
(String s) -> System.out.print(s)
public class Java8Tester {
public static void main(String args[]){
Java8Tester tester = new Java8Tester();
// 類型聲明
MathOperation addition = (int a, int b) -> a + b;
// 不用類型聲明
MathOperation subtraction = (a, b) -> a - b;
// 大括號(hào)中的返回語(yǔ)句
MathOperation multiplication = (int a, int b) -> { return a * b; };
// 沒(méi)有大括號(hào)及返回語(yǔ)句
MathOperation division = (int a, int b) -> a / b;
System.out.println("10 + 5 = " + tester.operate(10, 5, addition));
System.out.println("10 - 5 = " + tester.operate(10, 5, subtraction));
System.out.println("10 x 5 = " + tester.operate(10, 5, multiplication));
System.out.println("10 / 5 = " + tester.operate(10, 5, division));
// 不用括號(hào)
GreetingService greetService1 = message ->
System.out.println("Hello " + message);
// 用括號(hào)
GreetingService greetService2 = (message) ->
System.out.println("Hello " + message);
greetService1.sayMessage("Runoob");
greetService2.sayMessage("Google");
}
interface MathOperation {
int operation(int a, int b);
}
interface GreetingService {
void sayMessage(String message);
}
private int operate(int a, int b, MathOperation mathOperation){
return mathOperation.operation(a, b);
}
}
輸出結(jié)果為:
$ javac Java8Tester.java
$ java Java8Tester
10 + 5 = 15
10 - 5 = 5
10 x 5 = 50
10 / 5 = 2
Hello Runoob
Hello Google
