treeset comparator

; This. Shuxue =Shuxue; This. Yingyu =Yingyu; } PublicStudent () {Super(); } @Override PublicString toString () {return"Student [name=" + name + ", yuwen=" + Yuwen + ", shuxue=" + Shuxue + ", yingyu=" + Yingyu + "]"; }}The comparator is an anonymous inner class, Collections.sort (List,comparatorThe Compare method is then implemented, returning a value of type int, positive negative 0 representing greater than or equal toAdd the content code of I

There are two ways to sort a property of an object in a collection. A. One is to sort the object class to implement the comparable interface CompareTo method, then put the object into the list, then call Collections.sort (list);B. One is not to make any changes to the Sort object class, create the implementation class C of the comparator interface, then put the object into the list, and then call Collections.sort (list, C); A.eg ---------------------

1, the entity class implements the comparable interface, the rewriting CompareTo method Package io; Import Java.text.DateFormat; Import java.text.ParseException; Import Java.text.SimpleDateFormat; Import Java.util.Date; public class Student implements comparable Package io; Import java.util.ArrayList; Import java.util.Collections; Import java.util.List; public class App. {public static void Main (string[] args) { list 2, create a new business class implementation

Because the original sort API is actually the first to compare the number of converted to a string and then compare, so it is not easy to useSo prepare to customize a comparer function:1 //Sort Principle--->sort (arr,compare)2 functionSort (arr,compare) {3 if(compare===undefined) {//If compare is undefined, a compare original comparator is created, converted to a string for comparison, and if a custom comparer is passed in, the custom co

Goal: Achieve the age of the person object, from small to large sort1. Implementation sequencing1 PackageCom.app;23 Importjava.util.ArrayList;4 Importjava.util.Collections;5 ImportJava.util.Comparator;6 Importjava.util.List;7 8 Public classA1extendsb{9 Ten Public Static voidMain (string[] args) { OnelistGetData (); A //Sort - Collections.sort (list, comparator); - the for(person person:list) { -System.out.println ("per

Http://www.verejava.com/?id=169931036202101/** Knowledge Points: Comparative class Comparator title: A class of students according to mathematical results from small to large order of thought: 1. Abstract class: 1.1 Class (Classset) 1.2 Students (St Udent) 2. Find out the class relationship: 2.1 Students belong to class Student-Classset (many to 1) 3. Find class Properties: 3.1 Classset (class name, class number) 3.2 Student (student name, math score)

Copy Code code as follows: Import java.util.ArrayList; Import java.util.Collections; Import Java.util.Comparator; Import java.util.List; public class Comparatortest implements comparator /*** @param args*/public static void Main (string[] args) {listStuentity stud1=new stuentity ();Stud1.setage (10);Stud1.setname ("abc");Stuentity stud2=new stuentity ();Stud2.setage (10);Stud2.setname ("BDC");Stuentity stud3=new stuentity ();Stud3.setage

packagecom.heli.compare;importjava.text.collator;importjava.util.comparator;import java.util.locale;/*** @desc person class. person implements the comparable interface, which means that the person itself supports sorting */publicclassPersonimplements comparable packagecom.heli.compare;importjava.util.arraylist;importjava.util.collections;public Classtest{publicstaticvoidmain (String[]args) {// new ArrayList ( Dynamic array) arraylist Comparator sorted

sorting function has already been implemented in Java APIs. We do not haveWe need to repeat the wheel. The arrays class has a static method sort. With this method, we can import the array we want to sort into the sorting. Because we pass in an array reference, the sorting is complete.The result also uses this reference to change the array. for sorting integers and strings, JDK provides the default implementation. If you want to sort an array of objects, you must implementJava. util.

Three: Public classmyclass{ Public stringMyProperty1 {Get;Set; } Public stringMyProperty2 {Get;Set; }} Public classMyclassiequalitycomparer:iequalitycomparer{ Public BOOLEquals (MyClass x, MyClass y) {if(ReferenceEquals (x,NULL))return false; if(ReferenceEquals (Y,NULL))return false; if(ReferenceEquals (x, y))return true; returnx.myproperty1.equals (y.myproperty1); } Public intGetHashCode (MyClass obj) {returnobj. Myproperty1.gethashcode (); }}Usage:List. Distinct (new myclassiequal

Business requirements:Descending by number of participants, then by rank and ascendingNumber of people: pertotal, ranking of the sum: ranktotalFull code:@Overridepublic jsonobject gettopunitofgameranking (listkey part code (in the same number of cases, compare the sum of the rankings):listExamples of comparator in Java

Define binary operation class Binarytree{class node{private node left;//index private node right;//index private comparable data;public node (comparable　　This method is generally not recommended, direct recommendation, implements comparable, implement Comparato () methodJava:comparable Comparator, define binary operation class

Review. Record it by the way! Use collections. SortAndArrays.sortThere are two methods for sorting objects. The comparable interface of sorting objects overrides the compareto method and transmits the parameters for implementing the comparator interface to the sort method. The following sortobject object, the two methods are implemented. Package Oliver. java. Test. Sort; Test code: Package Oliver. java. test. sort;

+ mid +1; -DataType * End2 = arr + to +1; $DataType * temp = (DataType *)malloc(To- from+1)*sizeof(DataType)); $DataType * p =temp; - while((First1! = end1) (first2! =end2)) -*p++ = ((*compar) (First1, first2)? *first1++: *first2++); the if(First1 = =end1) - {Wuyi while(First2! =end2) the*p++ = *first2++; - } Wu Else - { About while(First1! =end1) $*p++ = *first1++; - } -p =temp; - for(inti = from; I ) AArr[i] = *p++; + Free(temp); the

public class CompareToImplementsComparator implements Comparator { 　　　 public int compare(Object o1, Object o2) { 　　　　　　int i=(Integer)o1; 　　　　　 　int j=(Integer)o2; 　　　　　 　if(i>j){ 　　　　　　　　return 1; 　　　　　　 　} 　　　　　return 0; 　　　　　} @SuppressWarnings("unchecked") public static void main(String[] args) { 　List 　for(int i=10;i>0;i--){ 　　　　　 list.add(i); 　} 　Collections.sort(list, new CompareToImplementsComparator()); 　　for(int j=0;j 　　　　　 　System.out.prin

PackageCom.swift;Importjava.util.ArrayList;Importjava.util.Collections;ImportJava.util.Comparator;Importjava.util.List; Public classMax_substring_test { Public Static voidMain (string[] args) {/** Maximum common substring of several strings*/String str1= "Eriousdfndnfdlk"; String str2= "Dkgfdkgkdjgdjgjksjgksgjsdkjsdierioe"; String STR3= "Ldskfjdskierundsnfjerioejrejrheruer3j43j4hj3"; String Sub; ListNewArraylist(); for(inti = 0; I ) {Sub= str1.substring (0, i); if(Str2.indexof (s

((String) O1, (string) O2);}else if (O1 instanceof Integer) {return compare ((integer) O1, (integer) O2);}else if (O1 instanceof person) {return compare (person) O1, (person) O2);}else {SYSTEM.ERR.PRINTLN ("No suitable comparator found");return 1;}}public int Compare (string O1, string O2) {string S1 = (string) O1;String s2 = (string) O2;/** SYSTEM.OUT.PRINTLN ("s1==" +s1+ "s2==" +s2);* Remove the array adjacent to the two surname FirstName or name L

In practice, we often have to implement some of the more bizarre sort. For example, in a group of [1,3,5,8,4,6,5], keep the original order unchanged, in the order of size. and establish a mapping relationship. (after sorting, use O (1) complexity to query the position of the first large number in the original array)such as thisIndex 0 1 2 3 4 5 6Arr 1 3 5 8 4 6 5Sort 6 5 2 0 4 1 3 For the algorithm party, this time can hand tear a fast platoon or merge and so on. (But if it's in the game,

Package com; Import java.util.ArrayList; Import java.util.Collections; Import Java.util.Comparator; Import java.util.List; public class Comparatordemo {public list 1, Comparator Collections.sort (list 2, T implements the comparable interface Collections.sort (list

TreeMap, Comparable, and Comparator in JavaWe know that the storage location of HashMap is stored according to the hashCode of the key object, while that of TreeMap is stored according to the hashCode, it is stored according to the compareTo method of the implemented Comparable interface. As long as the returned result of compareTo is 0, the two objects are equal, so there will be no two objects, the put method overwrites the previous one. We don't ev