java8已经出了很久,项目中也在使用。其最重要的特性就是Lambda表达式和函数式编程,这让我们的代码可以大大简化,更加优雅。
Lambda表达式
/**
* Created by liubenlong on 2016/11/7.
*/
public class LambdaTest {
/**
* lambda表达式测试
* @param args
*/
public static void main(String args[]){
LambdaTest tester = new LambdaTest();
//with type declaration
MathOperation addition = (int a, int b) -> a + b;
//with out type declaration
MathOperation subtraction = (a, b) -> a - b;
//with return statement along with curly braces
MathOperation multiplication = (int a, int b) -> { return a * b; };
//without return statement and without curly braces
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));
//with parenthesis
GreetingService greetService1 = message -> System.out.println("Hello " + message);
//without parenthesis
GreetingService greetService2 = (message) -> System.out.println("Hello " + message);
greetService1.sayMessage("Mahesh");
greetService2.sayMessage("Suresh");
}
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);
}
}
输出结果:
10 + 5 = 15
10 - 5 = 5
10 x 5 = 50
10 / 5 = 2
Hello Mahesh
Hello Suresh
重要的观点:
jdk中lambda表达式的典型用法:
Arrays.asList( "a", "b", "d" ).forEach( e -> System.out.println( e ) );
Arrays.asList( "a", "b", "d" ).sort( ( e1, e2 ) -> e1.compareTo( e2 ) );