集合排序TreeSet

package com.collection.test1;

public class UserModule1 implements Comparable{
// 定义一些属性
private String userId, name;
private int age;

public String getUserId() {
return userId;
}

public void setUserId(String userId) {
this.userId &＃61; userId;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name &＃61; name;
}

public int getAge() {
return age;
}

public void setAge(int age) {
this.age &＃61; age;
}

//重写hashCode和equals&＃xff0c;不用每个都比较&＃xff0c;一般只比较userId就行了
&＃64;Override
public int hashCode() {
System.out.println("call hashCode...");
final int prime &＃61; 31;
int result &＃61; 1;
result &＃61; prime * result &＃43; ((userId &＃61;&＃61; null) ? 0 : userId.hashCode());
return result;
}

&＃64;Override
public boolean equals(Object obj) {
System.out.println("call equals...");
if (this &＃61;&＃61; obj)
return true;
if (obj &＃61;&＃61; null)
return false;
if (getClass() !&＃61; obj.getClass())
return false;
UserModule1 other &＃61; (UserModule1) obj;
if (userId &＃61;&＃61; null) {
if (other.userId !&＃61; null)
return false;
} else if (!userId.equals(other.userId))
return false;
return true;
}

//覆盖toString
&＃64;Override
public String toString(){
return "userId&＃61;&＃61;"&＃43;userId&＃43;",age&＃61;&＃61;"&＃43;age&＃43;"&＃xff0c;name&＃61;&＃61;"&＃43;name;
}

&＃64;Override
public int compareTo(Object o) {
// TODO Auto-generated method stub
System.out.println("call compareTo");
//1、对象强制造型
UserModule1 us1&＃61; (UserModule1)o;
//2、比较
System.out.println("this.getUserId()&＃61;&＃61;"&＃43;this.getUserId()&＃43;",us1.getUserId()&＃61;&＃61;"&＃43;us1.getUserId());
if(this.getUserId().compareTo(us1.getUserId())>0){
System.out.println(">>>>");
return 1;
}else if(this.getUserId().compareTo(us1.getUserId())&＃61;&＃61;0){
System.out.println("&＃61;&＃61;&＃61;&＃61;");
return 0;
}else{
System.out.println("<<<");
return -1;
}

}
}

package com.collection.test1;

import java.util.Collection;
import java.util.Iterator;
import java.util.TreeSet;

public class CollectionTest4 {
public static void main(String args[]) {
addMethod();
}

private static void addMethod() {
//Collection col &＃61; new ArrayList();
Collection col &＃61; new TreeSet();
//Collection col &＃61; new HashSet();
UserModule1 user1 &＃61; new UserModule1();
user1.setAge(1);
user1.setName("suus");
user1.setUserId("1");
System.out.println("call set11");
// 调用add&＃xff0c;就会调用hashCode
col.add(user1);


UserModule1 user2 &＃61; new UserModule1();
user2.setAge(2);
user2.setName("suus2");
user2.setUserId("5");
System.out.println("call set22");
col.add(user2);


UserModule1 user3 &＃61; new UserModule1();
user3.setAge(3);
user3.setName("suus3");
user3.setUserId("6");
System.out.println("call set33");
col.add(user3);

// 2enum,Iterator是一个接口&＃xff0c;不能直接new&＃xff0c;
Iterator it &＃61; col.iterator();
while (it.hasNext()) {
// 得到的it是Object类型的
UserModule1 a &＃61; (UserModule1) it.next();
// 如果要想打印自己定义的类的各个对象&＃xff0c;必须要重写toString方法。打印对象的时候&＃xff0c;调用toString方法
System.out.println("a&＃61;&＃61;" &＃43; a);
}

}

}