两个概念函数式接口函数式接口就是只显式声明一个抽象方法的接口。为保证方法数量不多不少，java8提供了一个专用注解@FunctionalInterface，这样，当接口中声明的抽象方法多于或少于一个时就会报错。如下图所示：Lambda表达式Lambda表达式本质上是一个匿名方法。让我们来看下面这个例子：public int add(int x, int y) {
return x + y;
Lazy frogThere was once a frog who live in the depth of the unknown wells, one day he wanted to walk out.But he was lazy, climb three meters daytime and night will fall two meters.If given the well de
# Spark Lazy Evaluation
## Introduction
In Apache Spark, lazy evaluation is a critical concept that improves the efficiency and performance of data processing. Lazy evaluation refers to the postpone
