JAVA8新特性学习总结

• 函数式编程
• 流
• Ｏptional类
• 日期时间API
• Base64

一、函数式编程

函数式编程的基本理论不再讲述，说一下个人的理解，函数式编程的直接好处是代码层次的复用与抽象，使代码更简洁，复用度更高

以下实例完成一下对象的数据比较过程，对比非函数化编程与函数化编程的优缺点，期望对大家有所帮助。以下是对苹果重量进行排序的过程
1、创建一个Apple实体类：

public class Apple {
    private Integer weight; //重量
    private String color; //颜色

    public Apple(Integer weight, String color) {
        this.weight = weight;
        this.color = color;
    }

    public Integer getWeight() {
        return weight;
    }

    public void setWeight(Integer weight) {
        this.weight = weight;
    }

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }

    @Override
    public String toString() {
        return "Apple{" +
                "weight=" + weight +
                ", color='" + color + '\'' +
                '}';
    }
}

2、JAVA7中的实现：

    @Test
    public void testJava7() {
        //创建苹果列表
        List appleList = Arrays.asList(
                new Apple(36, "green")
                , new Apple(45, "red")
                , new Apple(89, "orange")
                , new Apple(102, "red")
                , new Apple(39, "green")
        );
        //排序前
        System.out.println(appleList);
        //排序
        appleList.sort(new Comparator() {
            @Override
            public int compare(Apple o1, Apple o2) {
                return o1.getWeight().compareTo(o2.getWeight());
            }
        });
        //排序后
        System.out.println(appleList);
    }

3、JAVA8中实现排序

    @Test
    public void testJava8() {
        List appleList = Arrays.asList(
                new Apple(36, "green")
                , new Apple(45, "red")
                , new Apple(89, "orange")
                , new Apple(102, "red")
                , new Apple(39, "green")
        );
        //排序前
        System.out.println(appleList);
        appleList.sort(Comparator.comparing(Apple::getWeight));
        //排序后
        System.out.println(appleList);
    }

// todo 20190729 未完待更.................