1.使用HashSet之前,一定要实现存储对象的hashCode(),equals(),
2.HashSet使用不当(存储对象的hash值改变),可能会造成内存泄漏
import java.util.HashSet;
import java.util.Set;
public class MemoryLeap {
public static void main(String[] args){
Set<Person> set = new HashSet<Person>();
Person p1 = new Person("唐僧","pwd1",25);
Person p2 = new Person("孙悟空","pwd2",26);
Person p3 = new Person("猪八戒","pwd3",27);
set.add(p1);
set.add(p2);
set.add(p3);
System.out.println(set.size());//输出3
p3.setAge(2);//p3的hash值改变,
set.remove(p3);//remove不掉
set.add(p3);//添加成功!!
System.out.println(set.size());//输出4
}
}
**************************Person类代码如下**********************************
public class Person {
public String name;
public String pwd;
public int age;
public Person(String name,String pwd,int age){
this.age=age;
this.name=name;
this.pwd=pwd;
}
public void setAge(int age){
this.age=age;
}
@Override
public boolean equals( Object obj){
return (this.name.equals(((Person) obj).name));
}
@Override
public int hashCode(){
return this.name.hashCode()+age;
}
}