java8 流

实现：赛选苹果

基类

public class Apple {
	private String color;
	private int weight;
	
	
	public String getColor() {
		return color;
	}
	public void setColor(String color) {
		this.color = color;
	}
	public int getWeight() {
		return weight;
	}
	public void setWeight(int weight) {
		this.weight = weight;
	}
	
	public static boolean isGreenApple(Apple apple) {
		return "green".equals(apple.getColor());
	}
	public static boolean isHeavyApple(Apple apple) {
		return apple.getWeight() > 150;
	}
}

　　方法类：

　　　　原始做法　　　
　　　　　public static List<Apple> filterGreenApples(List<Apple> inventory){
			List<Apple> result = new ArrayList<>();
			for (Apple apple: inventory){
				if ("green".equals(apple.getColor())) {
				result.add(apple);
				}
			}
			return result;
		}
		
		public static List<Apple> filterHeavyApples(List<Apple> inventory){
			List<Apple> result = new ArrayList<>();
			for (Apple apple: inventory){
				if (apple.getWeight() > 150) {
				result.add(apple);
				}
			}
			return result;
		}
		
		java8  做法
		//----------------------------------------------------------------------
		static List<Apple> filterApples(List<Apple> inventory,
			Predicate<Apple> p) {
			List<Apple> result = new ArrayList<>();
			for (Apple apple: inventory){
				if (p.test(apple)) {
				result.add(apple);
				}
			}
			return result;
		}
		
		public static void main(String[] args) {
			List<Apple> inventory = new ArrayList<>();
			List<Apple> result = filterApples(inventory, (Apple a)-> "green".equals(a.getColor()));
		}

　知识点：

　

如上图，接口类，可以写default 开头的方法，此方法可以直接写实现，而且，子类不用集成此方法