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

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

Java代码

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;

}

Java代码

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

——————-你懂的————————

Apple,1

Facebook,2

Twitter,3

Youtube,4

Telerik,5

Google,6

google guava代码：

Java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());

}

Java代码

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);

}

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Java代码

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

不静之心

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

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不静之心

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

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