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;
     }
 }