利用apache Collections和google guava对list和map进行过滤和排序

    在工作中，我们常常需要对List或者Map等集合结果过滤或者排序，这里我通过使用apache commons和google guava中的方法，简单实现了一下，方便以后使用。

    例子中使用的是apache commons3.1和google-guava14，最新版本是18

    apache项目下载地址：http://projects.apache.org/indexes/quick.html

    apache Collectoins下载地址：http://commons.apache.org/proper/commons-collections/

    apache代码如下：

    对List中的对象按不同属性排序，请看此

package com.umapp.test;

public class UserGuava {
	private String name;
	private int age;
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + age;
		result = prime * result + ((name == null) ? 0 : name.hashCode());
		return result;
	}
	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		UserGuava other = (UserGuava) obj;
		if (age != other.age)
			return false;
		if (name == null) {
			if (other.name != null)
				return false;
		} else if (!name.equals(other.name))
			return false;
		return true;
	}
	public UserGuava(){
		
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
}

 

 

    

package com.umapp.test;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.commons.collections.Predicate;
import org.apache.commons.collections.iterators.FilterIterator;
import org.apache.commons.collections.iterators.UniqueFilterIterator;

public class TestApache {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		List<UserGuava> list = new ArrayList<UserGuava>();
		UserGuava user = new UserGuava();
		user.setAge(1);
		user.setName("Apple");
		list.add(user);
		user = new UserGuava();
		user.setAge(2);
		user.setName("Facebook");
		list.add(user);
		user = new UserGuava();
		user.setAge(3);
		user.setName("Twitter");
		list.add(user);
		user = new UserGuava();
		user.setAge(4);
		user.setName("Youtube");
		list.add(user);
		user = new UserGuava();
		user.setAge(5);
		user.setName("Telerik");
		list.add(user);
		user = new UserGuava();
		user.setAge(6);
		user.setName("Google");
		list.add(user);
		user = new UserGuava();
		user.setAge(6);
		user.setName("Google");
		list.add(user);
        Predicate predicate=new Predicate(){           
			@Override
			public boolean evaluate(Object arg0) {
				UserGuava u = (UserGuava)arg0;
				return u.getAge()>2;
			}
        };
        Iterator<?> iterator=new FilterIterator(list.iterator(),predicate);
        while(iterator.hasNext()){
        	UserGuava u = (UserGuava)iterator.next();
            System.out.println(u.getName()+","+u.getAge());
        }
        System.out.println("-------------------你懂的------------------------");
        Iterator iterator1=new UniqueFilterIterator(list.iterator());
        while(iterator1.hasNext()){
        	UserGuava u = (UserGuava)iterator1.next();
            System.out.println(u.getName()+","+u.getAge());
        }
	}

}

 
 

 

    打印结果：

      Twitter,3

      Youtube,4

      Telerik,5

      Google,6

      Google,6

-------------------你懂的------------------------

      Apple,1

      Facebook,2

      Twitter,3

      Youtube,4

      Telerik,5

      Google,6

 

      google guava代码：

     

package com.umapp.test;

import java.util.Comparator;

public class NameComparator implements Comparator<UserGuava> {
    @Override
    public int compare(UserGuava user, UserGuava user1) {
        return user.getName().compareTo(user1.getName());
    }
}

 

 

   

package com.umapp.test;

import java.util.Comparator;

public class AgeComparator implements Comparator<UserGuava> {
    @Override
    public int compare(UserGuava user, UserGuava user1) {
        return user.getAge() > user1.getAge() ? 1 : (user.getAge() == user1.getAge() ? 0 : -1);
    }
}

 

 

   

package com.umapp.test;

import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Objects;

import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.Collections2;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.Ordering;

public class TestGuava {

	public static void main(String[] args) {
		Map<String, UserGuava> map = Maps.newHashMap();
		List<UserGuava> list = Lists.newArrayList();
		UserGuava user = new UserGuava();
		user.setAge(1);
		user.setName("JetBrains");
		map.put("1", user);
		list.add(user);
		user = new UserGuava();
		user.setAge(2);
		user.setName("Apple");
		list.add(user);
		map.put("2", user);
		user = new UserGuava();
		user.setAge(3);
		user.setName("Telerik");
		list.add(user);
		map.put("3", user);
		user = new UserGuava();
		user.setAge(4);
		user.setName("Google");
		list.add(user);
		map.put("4", user);
		user = new UserGuava();
		user.setAge(5);
		user.setName("Twitter");
		list.add(user);
		map.put("5", user);
		user = new UserGuava();
		user.setAge(2);
		user.setName("Facebook");
		list.add(user);
		map.put("2", user);
		user = new UserGuava();
		user.setAge(1);
		user.setName("Youtube");
		map.put("1", user);
		list.add(user);
		Predicate<UserGuava> preFilter = new Predicate<UserGuava>(){
			@Override
			public boolean apply(UserGuava user) {
				return user.getAge()>2;
			}
		};
		for (Entry<String, UserGuava> e : map.entrySet()) {
			if (preFilter.apply(e.getValue())) {
				UserGuava u= (UserGuava)e.getValue();
				System.out.println("Map-UserGuava="+u.getName()+","+u.getAge());
			}
		}
		System.out.println("-------------------你懂的------------------------");
		for (UserGuava u:list) {
			if (preFilter.apply(u)) {
				System.out.println("List-UserGuava="+u.getName()+","+u.getAge());
			}
		}
		System.out.println("-------------------你懂的------------------------");
		Predicate<UserGuava> p1 = new Predicate<UserGuava> () {  
	        @Override  
	        public boolean apply(UserGuava user) {  
	            if (user == null) {  
	                return false;  
	            }  
	            if (Objects.equals(user.getAge(), 1)) {  
	                return false;  
	            }  
	            return true;  
	        }  
	    };
	    Predicate<UserGuava> p2 = new Predicate<UserGuava> () {  
	        @Override  
	        public boolean apply(UserGuava user) {  
	            if (user == null) {  
	                return false;  
	            }  
	            if (Objects.equals(user.getAge(), 2)) {  
	                return false;  
	            }  
	            return true;  
	        }  
	    };
	    Predicate<UserGuava> unionPredicate = Predicates.and(p1, p2);  
            //两种处理方式
	   // List<UserGuava> newUserList = Lists.newArrayList(Iterators.filter(list.iterator(), unionPredicate));
	    Collection<UserGuava> newUserList =(Collection<UserGuava>) Collections2.filter(list, unionPredicate);
	    for (UserGuava u:newUserList) {
			System.out.println("List-IN-UserGuava="+u.getName()+","+u.getAge());
		}
	    System.out.println("-------------------你懂的------------------------");
            //先按年龄，再按名称排序
	    Comparator<UserGuava> userComparator = Ordering
                .from(new AgeComparator()).compound(new NameComparator());

        Collections.sort(list, userComparator);
        for (UserGuava u:list) {
			System.out.println("List-Sort-UserGuava="+u.getName()+","+u.getAge());
		}
	}

}

    打印结果：

 

     Map-UserGuava=Telerik,3

     Map-UserGuava=Twitter,5

     Map-UserGuava=Google,4

-------------------你懂的------------------------

     List-UserGuava=Telerik,3

     List-UserGuava=Google,4

     List-UserGuava=Twitter,5

-------------------你懂的------------------------

     List-IN-UserGuava=Telerik,3

     List-IN-UserGuava=Google,4

     List-IN-UserGuava=Twitter,5

-------------------你懂的------------------------

     List-Sort-UserGuava=JetBrains,1

     List-Sort-UserGuava=Youtube,1

     List-Sort-UserGuava=Apple,2

     List-Sort-UserGuava=Facebook,2

     List-Sort-UserGuava=Telerik,3

     List-Sort-UserGuava=Google,4

     List-Sort-UserGuava=Twitter,5