标签：分享 height 图片 array bsp 技术 system OLE 接口
《JAVA8实战》中的例子
要实现的功能：通过Apple的color或weight属性，对List<Apple>进行筛选。
1、首先定义com.owl.entity.Apple：
package com.owl.entity;
public class Apple { private String color; private Integer weight; public String getColor() { return color; } public void setColor(String color) { this.color = color; } public Integer getWeight() { return weight; } public void setWeight(Integer weight) { this.weight = weight; } }
2、生成一个简单的List<Apple>集合
package com.owl.app; import java.util.ArrayList; import java.util.List; import com.owl.entity.Apple; public class demo { public static void main(String[] args) { List<Apple> appleList = new ArrayList<Apple>(); Apple redApple = new Apple(); redApple.setColor("red"); redApple.setWeight(180); appleList.add(redApple); Apple greenApple = new Apple(); greenApple.setColor("green"); greenApple.setWeight(120); appleList.add(greenApple); } }
3、在com.owl.entity.Apple中定义筛选条件(绿苹果或者重量大于150的苹果)
public static boolean isGreenApple(Apple apple) { return "green".equals(apple.getColor()); } public static boolean isHeavyApple(Apple apple) { return apple.getWeight() > 150; }
4、在com.owl.app.demo中定义接口：
public interface Predicate<T> { boolean test(T t); }
5、在com.owl.app.demo中定义filter方法：
static List<Apple> AppleFilter(List<Apple> apples, Predicate<Apple> p) { List<Apple> resultApples = new ArrayList<Apple>(); for (Apple apple:apples) { if(p.test(apple)) { resultApples.add(apple); } } return resultApples; }
6、在main函数中使用filter筛选苹果
List<Apple> greenAppleSet = AppleFilter(appleList, Apple::isGreenApple); List<Apple> heavyAppleSet = AppleFilter(appleList, Apple::isHeavyApple); System.out.println("=======绿苹果======="); for (Apple apple:greenAppleSet) { System.out.println(apple.getColor()); } System.out.println("=======大苹果======="); for (Apple apple:heavyAppleSet) { System.out.println(apple.getWeight()); }
结果：
为了实现上述功能，除了需要定义筛选条件之外，仍需要定义Predicate<T>和AppleFilter方法未免太过麻烦，通过lambda表达式有更简单的写法：
List<Apple> greenAppleSet = appleList.stream().filter((Apple apple)->apple.getColor().equals("green")).collect(Collectors.toList());
List<Apple> heavyAppleSet = appleList.stream().filter((Apple apple)->apple.getWeight()>150).collect(Collectors.toList());
System.out.println("=======绿苹果=======");
for (Apple apple:greenAppleSet) {
System.out.println(apple.getColor());
}
System.out.println("=======大苹果=======");
for (Apple apple:heavyAppleSet) {
System.out.println(apple.getWeight());
}
标签：分享 height 图片 array bsp 技术 system OLE 接口
原文地址：https://www.cnblogs.com/wsfu/p/10228272.html
