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

xinxuaw231

http://www.jiancool.com/article/50723356810/
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