Java Collection Framework (HashSet custom elements are the same, overriding hashcode and the Equals method)

/*hashset Basic Operation
*--set: Elements are unordered, the order of deposit and withdrawal is inconsistent, the elements cannot be duplicated
* (use hash to determine if the same object)
*----HashSet: The underlying data structure is a hash table,
* The method of ensuring data uniqueness is to invoke the Hashcode () method that is deposited into the element
* and Equals (Object obj) method
* The Equals method is called only if the hashcode value is the same
*
* */

1 ImportJava.util.HashSet;2 ImportJava.util.Iterator;3  Public classStudentcode {4     5      Public Static voidMain (String []args) {6         //define HashSet, and add data7HashSet hs=NewHashSet ();8Hs.add (NewPerson ("Lisi", 11));9Hs.add (NewPerson ("Zhangsan", 22));TenHs.add (NewPerson ("Lisi", 22)); OneHs.add (NewPerson ("Lisi", 11)); A         //traversing data (when outputting data with iterators, data operations can only be performed with iterators: Adding and removing changes, not working with objects) -          for(Iterator it=hs.iterator (); It.hasnext ();) { -Person p=(person) it.next (); theSystem.out.println ("Name:" +p.getname () + ", Age:" +p.getage ()); -         } -     } - } + classperson{ -     PrivateString name; +     Private intAge ; APerson (String name,intAge ) { at          This. name=name; -          This. age=Age ; -     } -      PublicString GetName () { -         return  This. Name; -     } in      Public intGetage () { -         return  This. Age; to     } +     //override the Hashcode () method to return a fixed hash value -      Public inthashcode () { the         return60; *     } $     //override the Equals (Object obj) method to define the required comparison of variablesPanax Notoginseng      Public Booleanequals (Object obj) { -         //determine if the incoming obj is a variable that is transformed by a person the         if(! (objinstanceofPerson )) +             return false; A         //transforms a person object onto an incoming object thePerson p=(person) obj; +         //determine whether two objects are of equal name and age, and equal are considered to be the same object -         return  This. Name.equals (P.getname ()) && This. age==p.getage (); $     } $}

Java Collection Framework (HashSet custom elements are the same, overriding hashcode and the Equals method)