Java Basic Knowledge Enhancement Collection Framework note 47:set set TreeSet guarantee element uniqueness and comparator ordering principle and code implementation (comparator sort)

1. TreeSet guarantee Element uniqueness and comparator ordering principle and code implementation (comparator sort)

(1)Student. Java:

1  Packagecn.itcast_07;2 3  Public classStudent {4     PrivateString name;5     Private intAge ;6 7      PublicStudent () {8         Super();9     }Ten  One      PublicStudent (String name,intAge ) { A         Super(); -          This. Name =name; -          This. Age =Age ; the     } -  -      PublicString GetName () { -         returnname; +     } -  +      Public voidsetName (String name) { A          This. Name =name; at     } -  -      Public intGetage () { -         returnAge ; -     } -  in      Public voidSetage (intAge ) { -          This. Age =Age ; to     } +}

(2)Treesetdemo. Java:

1  Packagecn.itcast_07;2 3 ImportJava.util.Comparator;4 ImportJava.util.TreeSet;5 6 /*7 * Requirements: Please follow the name of the length of the order8  * 9 * TreeSet Sets the principle of guaranteed element ordering and uniquenessTen * Uniqueness: is based on whether the return of the comparison is determined by the.  One * Sort: A * A: Natural sorting (elements are comparative) - * Allow the class that the element belongs to to implement the natural sort interface comparable - * B: Comparator sort (set with comparison) the * Let the construction method of the collection receive a subclass object of the comparer interface Comparator -  */ -  Public classTreesetdemo { -      Public Static voidMain (string[] args) { +         //To create a collection object -         //treeset<student> ts = new treeset<student> ();//Natural Sort +         //Public TreeSet (Comparator Comparator)//Comparator Sort A         //treeset<student> ts = new treeset<student> (new Mycomparator ()); at  -         //if the parameter of a method is an interface, then the object that really wants to be the implementation class of the interface -         //and the anonymous inner class can implement this. -treeset<student> ts =NewTreeset<student> (NewComparator<student>() { - @Override -              Public intCompare (Student s1, Student S2) { in                 //name Length -                 intnum = S1.getname (). Length ()-s2.getname (). Length (); to                 //name Content +                 intnum2 = num = = 0?s1.getname (). CompareTo (S2.getname ()) - : num; the                 //Age *                 intnum3 = Num2 = = 0? S1.getage ()-s2.getage (): num2; $                 returnnum3;Panax Notoginseng             } -         }); the  +         //Creating Elements AStudent S1 =NewStudent ("Linqingxia", 27); theStudent s2 =NewStudent ("Zhangguorong", 29); +Student s3 =NewStudent ("Wanglihong", 23); -Student S4 =NewStudent ("Linqingxia", 27); $Student S5 =NewStudent ("Liushishi", 22); $Student s6 =NewStudent ("Wuqilong", 40); -Student s7 =NewStudent ("Fengqingy", 22); -Student S8 =NewStudent ("Linqingxia", 29); the  -         //adding elementsWuyi Ts.add (S1); the ts.add (S2); - Ts.add (S3); Wu Ts.add (S4); - Ts.add (S5); About Ts.add (S6); $ Ts.add (S7); - Ts.add (S8); -  -         //Traverse A          for(Student s:ts) { +System.out.println (S.getname () + "---" +s.getage ()); the         } -     } $}

The results of the operation are as follows:

Java basic Knowledge Hardening Collection Framework note 47:set set TreeSet guarantee element uniqueness and comparator ordering principle and code implementation (comparator sort)