The definition and special function realization of java--set frame TreeMap

Import Java.util.scanner;import java.util.set;import java.util.treemap;/* * Requirements: "AABABCABCDABCDE", Gets the number of occurrences of each letter in a string requires results: A (5) B (4) C (3) d (2) e (1) * * Analysis: * A: Define a string (can be improved for keyboard entry) * B: Define a TREEMAP set * key: Character * Value: Integer * C: Convert a string to a character array * D: Iterate through the character array to get each character * E: Take the character you just got as a key into the collection to find the value, see the return value * is null: The key is not present, the character as a key, 1 as the value of the store * is NOT NULL: The key exists, the value of 1 Then override store the key and value * F: Define the string buffer variable * G: Iterate through the collection, get the keys and values, perform the stitching as required * H: Convert the string buffer to a string output * * Input: Linqingxia * Results: result:a (1) G (1) I (3) L (1) n (2) Q (1) x (1) */public class Treemapdemo {public static void main (string[] args) {//define a string (can be improved for keyboard entry) Scanner sc = new Scanner ( system.in); System.out.println ("Please enter a string:"); String line = Sc.nextline ();//define a TreeMap collection Treemap<character, integer> TM = new Treemap<character, integer> ();//Convert a string to a character array char[] CHS = Line.tochararray ();//Iterate through the character array, get each character for (char Ch:chs) {///take the obtained character as a key into the collection to find the value, see the return value of the integer i = Tm.get (ch);//IS null: Indicates that the key does not exist, put the character as a key, and 1 as the value to store if (i = = null) {tm.put (ch, 1);} else {//is NOT NULL: Indicates that the key exists, adds a value of 1, and then overrides store the key and value I++;tm.put (Ch,i);}} Defines the string buffer variableVolume StringBuilder sb= new StringBuilder ();//Iterate through the collection, get the keys and values, and make the stitching set<character> set = Tm.keyset () as required; for (Character key: Set) {Integer value = Tm.get (key); Sb.append (Key). Append ("("). Append (Value). Append (")");} Converts a string buffer to a string output of the strings result = Sb.tostring (); SYSTEM.OUT.PRINTLN ("Result:" +result);}}

Import Java.util.set;import java.util.treemap;/* * TreeMap: is the implementation of the map interface based on the red-black tree. *  * hashmap<string,string> * Key: String * Value: String */public class Treemapdemo {public static void main (string[] Ar GS) {//Create collection Object treemap<string, string> tm = new treemap<string, string> ();//create element and add element tm.put ("Hello", "Hello"); Tm.put ("World"), Tm.put ("Java", "Javanese"), Tm.put ("World", "Worlds 2"), Tm.put ("Java ee", "java ee");//Traversal collection set<string> Set = Tm.keyset (); for (string key:set) {String value = Tm.get (key); SYSTEM.OUT.PRINTLN (key + "---" + value);}}}

Import Java.util.comparator;import java.util.set;import java.util.treemap;/* * treemap<student,string> * key: Student * Value: String */public class TreeMapDemo2 {public static void main (string[] args) {//Create collection Object Treemap<student, Strin g> TM = new treemap<student, string> (new comparator<student> () {@Overridepublic int compare (Student s1, St Udent s2) {//main condition int num = s1.getage ()-s2.getage ();//Secondary condition int num2 = num = = 0? s1.getname (). CompareTo (S2.getname ()): Num;return num2;}); /Create student object Student S1 = new Student ("Koh Phangan", 30); Student s2 = new Student ("Willow Xia Hui", 35); Student s3 = new Student ("Tong Pak Fu", 33); Student S4 = new Student ("燕青", 32); Student S5 = new Student ("Tong Pak Fu", 33);//Storage element Tm.put (S1, "Song Dynasty"), Tm.put (S2, "Yuan Dynasty"), Tm.put (S3, "Ming Dynasty"), Tm.put (S4, "Qing Dynasty"); Tm.put (S5 , "Han Dynasty");//traverse set<student> set = Tm.keyset (); for (Student key:set) {String value = Tm.get (key); System.out.println (Key.getname () + "---" + key.getage () + "---" + value);}}}

Import Java.util.arraylist;import java.util.hashmap;import java.util.set;/* * In order to better meet the requirements: * This time the data is regarded as a student object. * * Preach Wisdom Podcast * BJ Beijing Campus * JC Basic class * Brigitte 27 * Wind Qingyang * JY Employment class * Gigi 28 * Wu Xin * SH Shanghai Campus * JC Basic class * Guo Meimei 20 * sharp Brother X JY Employment class * Luo yufeng 21 * Ma Zheng 23 * GZ Guangzhou Campus * JC Basic class * Leehom 30 * Li Jinglei * JY Employment class * Lang 31 * spokesperson * XA Xian Campus * JC Basic class * Fan Bingbing 27 * Elina * JY Employment class * Li Bingbing 28 * Zhangzhihao */public CL Hashmapdemo {public static void main (string[] args) {//Create large collection hashmap<string, hashmap<string, arraylist< student>>> Czbkmap = new hashmap<string, hashmap<string, arraylist<student>>> ();// Beijing Campus Data hashmap<string, arraylist<student>> bjczbkmap = new hashmap<string, arraylist<student> > (); arraylist<student> array1 = new arraylist<student> (); Student S1 = new Student ("Brigitte", 27); Student s2 = new Student ("Wind Qing"), Array1.add (S1); Array1.add (S2); arraylist<student> array2 = new arraylist<student> (); Student s3 = new Student ("Gigi", 28); Student S4 = new Student ("Wu Xin"); arrAy2.add (S3), Array2.add (S4), Bjczbkmap.put ("Basic Course", array1), Bjczbkmap.put ("Employment Class", array2), Czbkmap.put ("Beijing Campus", BJCZBKMAP);//You can practice it yourself//Shanghai Campus Data do//Guangzhou campus Data do//XI ' an campus data hashmap<string, arraylist<student>> Xaczbkmap = New hashmap<string, arraylist<student>> (); arraylist<student> array3 = new arraylist<student> (); Student S5 = new Student ("Fan Bingbing", 27); Student s6 = new Student ("Elina", +) Array3.add (S5); Array3.add (S6); arraylist<student> array4 = new arraylist<student> (); Student s7 = new Student ("Li Bingbing", 28); Student s8 = new Student ("Zhangzhihao"), Array4.add (S7), Array4.add (S8), Xaczbkmap.put ("Basic Class", Array3), Xaczbkmap.put ("Employment Class", ARRAY4); Czbkmap.put ("Xi ' an campus", xaczbkmap);//Traverse collection set<string> Czbkmapset = Czbkmap.keyset (); for (String Czbkmapkey: Czbkmapset) {System.out.println (Czbkmapkey); hashmap<string, arraylist<student>> czbkmapvalue = Czbkmap.get (Czbkmapkey); set<string> Czbkmapvalueset = Czbkmapvalue.keyset (); for (String CZBKMAPVALUEKEY:CZBKmapvalueset) {System.out.println ("\ T" + czbkmapvaluekey); arraylist<student> Czbkmapvaluevalue = Czbkmapvalue.get (Czbkmapvaluekey); for (Student S:czbkmapvaluevalue) { System.out.println ("\t\t" + s.getname () + "---" + s.getage ());}}}}

The definition and special function realization of java--set frame TreeMap