重写equals必须重写hashCode
public boolean equals(Object obj){
if(obj instanceof Name){
Name name = (Name) obj;
return (firstName.equals(name.firstName))&&(lastName.equals(name.lastName));
}
return super.equals(obj);
}
public int hashCode(){
return firstName.hashCode();
}
原文：http://www.cnblogs.com/qiantianyu/p/4369790.html