Java 8 行为参数化

行为参数化

public interface ApplePredicate<T> {
	boolean test(T t);
}

public class AppleWeightPredicate implements ApplePredicate<Apple>{
    public boolean test(Apple apple){
    	return apple.getWeight() > 150; 
    }
}
public class AppleColorPredicate implements ApplePredicate<Apple>{
    public boolean test(Apple apple){
    	return "green".equals(apple.getColor());
    }
}
//传递代码
// filter方法的行为取决于ApplePredicate对象传递的代码，也就是方法的行为参数化
public static<T> List<T> filter(List<T>inventory, ApplePredicate<T> p){
    List<T> result = new ArrayList<>();
    for(T t : inventory){
    	if(p.test(t)){
    	    result.add(t);
    	}
    }
    return result;
}   

List<Apple> heavyApples = filter(inventory, new AppleWeightPredicate());
List<Apple> greenApples2 = filter(inventory, new AppleColorPredicate());
// 匿名类方式
List<Apple> redApples2 = filter(inventory, new ApplePredicate() {
    public boolean test(Apple a){
    	return a.getColor().equals("red"); 
    }
});
//Lambda表达式
List<Apple> greenApples3 = filter(inventory, apple -> "green".equals(apple.getColor()));
List<Apple> heavyApples3 = filter(inventory, apple -> apple.getWeight() > 150);