JAVA 函数式参数

  @Test
    public void t1() {
        funcTestCase("a", String::toUpperCase);
    }

    public void funcTestCase(String a, function<String, String> func) {
        System.out.println(func.apply(a));
    }
    @FunctionalInterface
     interface function<T, R> {

//        T apply();

        R apply(T t);
    }