1. Lambda表达式
    1.     @FunctionalInterface
    2.     interface MyOperation{
    3.         abstract float operation(float a, float b);
    4.     }
    6.     @Test
    7.     public void testLambda(){
    8.         float a = 123;
    9.         float b = 234;
    10.         // 有参数、有返回值、多条语句使用{ }
    11.         float ret1 = fun(a, b, (float x, float y) -> {
    12.             System.out.println("求和计算");
    13.             return x + y;
    14.         });
    15.         System.out.println(ret1);
    17.         // 参数类型可省略，仅一条返回值语句，return可省略
    18.         float ret2 = fun(a, b, ( x, y) -> x + y);
    19.         System.out.println(ret2);
    20.     }
    22.     private float fun(float a, float b, MyOperation m){
    23.         return m.operation(a, b);
    24.     }