package com.ddy;
public class User {
private Integer id;
private String name;
private String address;
private String phone;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name == null ? null : name.trim();
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address == null ? null : address.trim();
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone == null ? null : phone.trim();
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.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;
User other = (User) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
return true;
}
public User(Integer id) {
super();
this.id = id;
}
}
Person根据id重写了equals和hashCode方法；这样HashSet添加people的时候会将id重复的people对象视为同一个people对象。
package com.ddy;
import java.util.HashSet;
import java.util.Set; public class Test {
public static void main(String[] args) {
User user1 = new User(1);
User user2 = new User(1);
Set<User> users = new HashSet<>();
users.add(user2);
users.add(user1);
System.out.println(users);
}
}
输出结果：[com.ddy.User@20]