Java中取两个集合的并集、交加和差集

package org.suk;

import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.List;

/**
* Description: <br/>
* @version V1.0  by 石冬冬-Heil Hitler on  2017/4/7 13:08
*/
public class Test {
/**
* Description: 并集<br>
* @version V1.0 2017/4/7 13:09  by 石冬冬-Heil Hilter（dd.shi02@zuche.com)
* @return
*/
public static void union(){
List<String> list1 = new ArrayList<String>(){{
add("A");
add("B");
add("C");
}};
List<String> list2 = new ArrayList<String>(){{
add("C");
add("D");
add("B");
}};
//求出并集
list1.addAll(list2);
System.out.println(list1);
}

/**
* Description: 交集<br>
* @version V1.0 2017/4/7 13:09  by 石冬冬-Heil Hilter（dd.shi02@zuche.com)
* @return
*/
public static void intersection(){
List<String> list1 = new ArrayList<String>(){{
add("A");
add("B");
add("C");
}};
List<String> list2 = new ArrayList<String>(){{
add("C");
add("D");
add("B");
}};
//求出交集
list1.retainAll(list2);
System.out.println(list1);
}

/**
* Description: 差集<br>
* @version V1.0 2017/4/7 13:09  by 石冬冬-Heil Hilter（dd.shi02@zuche.com)
* @return
*/
public static void diff(){
List<String> list1 = new ArrayList<String>(){{
add("A");
add("B");
add("C");
}};
List<String> list2 = new ArrayList<String>(){{
add("C");
add("D");
add("B");
}};
//求出差集
list1.removeAll(list2);
System.out.println(list1);
}
/**
* Description: 对象集合的交集<br>
* @version V1.0 2017/4/7 13:21  by 石冬冬-Heil Hilter（dd.shi02@zuche.com)
* @param null
* @return
*/
public static void test(){
List<Student> list1 = new ArrayList<Student>(){{
add(new Student("Linda",20));
add(new Student("Bruce",20));
add(new Student("Linda",21));
}};
List<Student> list2 = new ArrayList<Student>(){{
add(new Student("Linda",21));
add(new Student("Bruce",22));
add(new Student("Jack",21));
}};
//求出交集
list1.retainAll(list2);
System.out.println(list1);
}

public static void main(String[] args) {
union();
intersection();
diff();
test();
}
/**
* Description: 内部学生类<br>
* @version V1.0 2017/4/7 13:20  by 石冬冬-Heil Hilter（dd.shi02@zuche.com)
* @param null
* @return
*/
public static class Student{
private String name;
private int age;

public Student(String name, int age) {
this.name = name;
this.age = age;
}

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;
}

@Override
public int hashCode() {
return (this.getName() + String.valueOf(this.getAge())).hashCode();
}

@Override
public boolean equals(Object obj) {
if(null == obj)
return false;
if(obj instanceof Student){
Student other = (Student)obj;
return this.getName().equals(other.getName()) && this.getAge() == other.getAge();
}
return false;
}

@Override
public String toString() {
return MessageFormat.format("[name:{0},age:{1}]",this.getName(),this.getAge());
}
}
}

[A, B, C, C, D, B]
[B, C]
[A]
[[name:Linda,age:21]]