Cara nggunakake kelas koleksi ArrayList, Vector lan HashMap sing diwenehake dening Java Collections Framework

Ing artikel iki, kita bakal sinau babagan telung kelas koleksi penting ArrayList , Vector lan HashMap saka Framework Koleksi lan miwiti nggunakake ing kode kita dhewe. Nggunakake kelas koleksi ArrayListlan koleksi Vector, kita bisa nyimpen klompok unsur minangka obyek sing prasaja lan ngapusi kanthi nggunakake macem-macem cara sing kasedhiya ing kelas kasebut. Kelas ArrayListlan Vectorkasedhiya saka paket java.util. Kelas liyane yaiku koleksi, kasedhiya saka paket java.util, iki HashMap, sing ngidini sampeyan nyimpen koleksi pemetaan nilai kunci. Iki ndadekake iku bisa kanggo njupuk Nilai dikarepake saka koleksi nalika tombol dikenal. Coba deleng conto nggunakake kelas koleksi iki siji-siji. Conto 1. Ing conto iki, kita bakal nulis program prasaja nggunakake kelas - Listing koleksi ArrayList 1. Kode eksekusi contone 1

// подключаем класс
import java.util.ArrayList;
public class ArrayListExample {
  static String[] favouriteCharacters = {"Harry", "Ron", "Hermione",  "Snape", "Dumbledore", "Moody", "Riddle", "Fred"};
   int i;
   public ArrayList favouritelist = new ArrayList();
// метод добавляет элементы ‘favouriteCharacters’ в ‘favouritelist’
 private void includeCharacters(String[]favouriteCharacters)
       {
        for (i = 0; i < favouriteCharacters.length; i++) {
            // добавление элементов по одному из массива ‘favouriteCharacters’
            favouritelist.add(favouriteCharacters[i]);
            printCharacters(i);
        }
// добавление элементов, посредством указания позиций
        favouritelist.add(1, "george");
        favouritelist.add(4, "Peter");
    }
// метод выводит элемент ‘favouritelist’ по указанной позиции
    private void printCharacters(int i) {
        System.out.println("Character " + (i + 1) + ":" + favouritelist.get(i));
    }
// метод выводит все элементы ‘favouritelist’
    private void printCharacters() {
        System.out.println("\n");
        for(int i=0;i<favouritelist.size();i++){
        System.out.println("Character" + (i + 1) + ":" + favouritelist.get(i));
    }    }
// метод возвращает размер коллекции ‘favouritelist’
    private int sizeofCharactersList() {
        System.out.println("\n");
        System.out.println("Total No of Characters in Array:" + favouriteCharacters.length);
        System.out.println("Total No of Characters in List:" + favouritelist.size());
        return favouritelist.size();
    }
// метод выводит позицию element ‘favouritelist’ по указанному имени
 public void getCharacterPostion(String characterName) {
     System.out.println("\n");
        System.out.println("The position of the character\t" + characterName + "\tis\t" + favouritelist.indexOf(characterName));
    }
// метод удаляет элемент ‘favouritelist’ по указанному имени
    public void removeCharacter(String characterName) {
        if(favouritelist.size()>favouriteCharacters.length){
        favouritelist.remove(characterName);
        }
        else{
             System.out.println("\n");
             System.out.println("The element\t"+favouritelist.get(favouritelist.indexOf(characterName))+"\tcannot be removed");
        }
        }
// метод удаляет элемент ‘favouritelist’ по указанной позиции
    public void removeCharacter(int i) {
        if(favouritelist.size()>favouriteCharacters.length){
        favouritelist.remove(i);
          }
        else{
            System.out.println("The element\t"+favouritelist.get(i)+"\tcannot be removed");
        }
    }
    public static void main(String args[]) {
        ArrayListExample example = new ArrayListExample();
        example.includeCharacters(favouriteCharacters);
        example.printCharacters();
        int size = example.sizeofCharactersList();
        example.getCharacterPostion("Ron");
        example.removeCharacter("Snape");
        example.removeCharacter(2);
        example.sizeofCharactersList();
        example.removeCharacter("Harry");
         example.removeCharacter(4);
    }
}

Mbukak program iki bakal ngasilake output ing ngisor iki:

Character 1:Harry
Character 2:Ron
Character 3:Hermione
Character 4:Snape
Character 5:Dumbledore
Character 6:Moody
Character 7:Riddle
Character 8:Fred


Character1:Harry
Character2:george
Character3:Ron
Character4:Hermione
Character5:Peter
Character6:Snape
Character7:Dumbledore
Character8:Moody
Character9:Riddle
Character10:Fred


Total No of Characters in Array:8
Total No of Characters in List:10


The position of the character	Ron	is	2


Total No of Characters in Array:8
Total No of Characters in List:8


The element	Harry	cannot be removed
The element	Dumbledore	cannot be removed

Ayo goleki conto program sing diwenehake, langkah demi langkah. Ing conto iki, ing baris pisanan program, kita ngimpor kelas - koleksi ArrayList. Banjur, kita gantian nggawe senar favouriteCharacterssing ngemot jeneng wong lan favouritelistconto koleksi ArrayList. Cara kasebut includeCharacters(args)bisa dipérang dadi rong bagéan. Ing bagean pisanan saka cara, unsur ditambahake saka larik menyang koleksi nggunakake daur ulang. Ing kasus iki, nambah unsur kanggo ArrayListwis rampung ing urutan padha kang dumunung ing Uploaded. Iki kedadeyan amarga kita ora nemtokake posisi kanggo unsur sing ditambahake ing koleksi kasebut. Nanging ing bagean kapindho metode kita, unsur ditambahake nggunakake indeksasi. Ing kasus iki, unsur ditambahake menyang koleksi ing posisi pas sing ditemtokake. Nalika unsur anyar ditambahake ing tengah koleksi ArrayList, unsur sing wis ana ing koleksi sing dumunung ing sanjabane posisi selipan tartamtu saka unsur anyar dipindhah menyang posisi sakteruse saka dhewe, mangkono nambah ukuran koleksi. Nalika kita ndeleng output pisanan, kita bakal weruh:

Total No of Characters in List: 10
Total No of Characters in Array: 8

Iki amarga saliyane Uploaded gadhah 8 unsur, kang ditambahake kanggo ArrayList, kita tegas nambah 2 unsur liyane, mangkono nambah ukuran koleksi kanggo 10. Cara getCharacterPosition(args)njupuk Nilai saka unsur (jeneng wong) lan nampilake posisi. unsur iki ing koleksi ArrayList. Yen ora ana unsur kasebut ing ArrayList, banjur nilai -1 ditampilake. Cara kasebut removeCharacter(args)mbusak nilai unsur sing ditemtokake (jeneng wong) saka koleksi kasebut, minangka argumen minangka indeks saka unsur kasebut utawa unsur kasebut dhewe. Ing kode ndhuwur, kita bisa sok dong mirsani sing ukuran koleksi kita wis dadi 8 tinimbang 10 amarga kasunyatan sing kita wis dibusak 2 unsur saka koleksi. Yen ukuran array lan koleksi padha, cara kasebut ngasilake baris ing ngisor iki:

The element Harry cannot be removed
The element Dumbledore cannot be removed

Eksekusi metode kasebut removeCharacter(args)mung dikondisikake kanthi kasunyatan manawa ukuran koleksi kudu luwih gedhe tinimbang ukuran array. Conto 2. Ing conto iki, kita bakal nulis program prasaja nggunakake kelas - Listing koleksi Vector 2. Kode eksekusi contone 2

// подключаем класс
import java.util.Vector;
public class VectorExample {
    Vector vector=new Vector();
    public void addCharacterandPrint(){
        vector.add("Weasley");
        vector.add("Potter");
        for(int i=0;i<vector.size();i++){
        System.out.println("The characters are\t"+vector.get(i));
        }
    }
    public static void main(String args[]){
        VectorExample example=new VectorExample();
        example.addCharacterandPrint();
        }
}

Mbukak program iki bakal ngasilake output ing ngisor iki:

The characters are Weasley
The characters are Potter

Kode ing ndhuwur mung conto cilik, kasedhiya minangka bukti sing ana ora akeh prabédan antarane koleksi ArrayListlan Vector. Koleksi Vectorbisa dimanipulasi kanthi cara sing padha karo koleksi ArrayList, nggunakake cara sing padha. Conto 3. Ing conto iki, kita bakal nulis program prasaja nggunakake HashMap Listing kelas koleksi 3. Kode eksekusi kanggo Conto 3

// подключаем класс
import java.util.HashMap;
public class HashMapExample {
    HashMap hashMap=new HashMap();
    String Books[]={"Famous Five","Goosebumps","Robinson Crusueo","Nancy Drew","The Cell","The Davinci Code","Harry Potter"};
    public void mapAuthors(){
        hashMap.put("Famous Five","Enid Blyton");
        hashMap.put("Goosebumps","R.L.Stine");
        hashMap.put("Nancy Drew","Carolyn Keene");
        hashMap.put("The Cell","Christopher Pike");
        hashMap.put("The Davinci Code","Dan Brown");
        hashMap.put("Harry Potter","J.K. Rowling");
    }
    public void getBookList(){
        for(int i=0;i<Books.length;i++){
            if(hashMap.containsKey(Books[i])){
                System.out.println("Author"+(i+1)+":\t"+hashMap.get(Books[i])+"\t"+Books[i]);
            }
            else{
                System.out.println("\nThe Imformation about the author of the book\t"+Books[i]+"\tis not available\n");
            }
        }
    }
    public static void main(String args[]){
        HashMapExample hashMapExample=new HashMapExample();
        hashMapExample.mapAuthors();
        hashMapExample.getBookList();
    }
}

Mbukak program iki bakal ngasilake output ing ngisor iki:

Author1: Enid Blyton Famous Five
Author2: R.L.Stine Goosebumps
The Information about the author of the book Robinson Crusueo is not available
Author4: Carolyn Keene Nancy Drew
Author5: Christopher Pike The Cell
Author6: Dan Brown The Davinci Code
Author7: J.K. Rowling Harry Potter

Ayo ndeleng kode ing ndhuwur, langkah demi langkah. Ing program conto iki, kita duwe Uploaded saka strings unsur sing jeneng saka buku misuwur. Cara kasebut mapAuthors()nggawe tampilan judhul buku karo penulise. Tombol ing kene yaiku judhul buku, lan nilai-nilai kasebut minangka penulis buku kasebut. Nalika metode kasebut diarani getBookList(), bakal diulang liwat array Bookslan entuk judhul buku siji-siji. Sabanjure, metode kasebut mriksa manawa ana buku sing duwe penulis dhewe. Kaya sing bisa dideleng, yen metode kasebut ora bisa nemokake penulis buku kasebut, pesen kasebut bakal ditampilake not available. Yen ora, penulis lan bukune ditampilake siji-siji. Kesimpulan: Ing artikel iki, kita sinau sethithik babagan kelas - koleksi ArrayList, Vector, HashMaplan nyoba digunakake ing kode kita dhewe. Artikel asli: Cara nggunakake kelas ArrayList, Vector lan HashMap sing diwenehake dening Java Collections Framework