Predicate接口和Consumer接口

Predicate和Consumer接口是集合操作中常用到的俩个接口：

1、Predicate

public interface Predicate<T>{
	boolean test(T t);//进行某些逻辑判断并返回一个boolean值
}

2、Consumer

public interface Consumer<T>{
	void accept(T t);//对于给定的对象进行操作
}

3、结合实例

• predicate

Predicate<Integer> pre = x -> x >= 5;
System.out.println(pre.test(9));//输出结果为true

• consumer

import java.util.Collection;
import java.util.HashSet;
import java.util.function.Predicate;
import java.util.function.Consumer;

public class PreCon {
    public static void main(String []args){
        Collection<String> c=new HashSet<String>();
        c.add("!");
        c.add("java");
        c.add("hao");
        c.add("ni");
        c.add("zhe");
        System.out.println(findSet(c,obj->System.out.println(obj),obj->((String)obj).length()<3));
        
        //使用Lambda表达式（目标类型是Predicate）过滤集合  
        c.removeIf(ele -> ((String)ele).length() < 10);
        System.out.println(c);  
    }

    public static int findSet(Collection collection, Consumer consumer,
            Predicate predicate) {
        int n = 0;
        for (Object obj : collection) {
            if (predicate.test(obj)) {
                n++;
                consumer.accept(obj);
            }
        }
        return n;
    }
}