Operasi Dasar Queue

Sebuah queue berisi beberapa elemen dengan tipe yang sama; disusun berurutan. Operasi queue terjadi pada kedua ujungnya. Penambahan di satu ujung (depan), penghapusan di ujung yang lain (belakang).

Contoh Program:

Source Code appQueue:

package pkgQueue;
import java.util.Scanner;
public class appQueue {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int Pilih = 0;
        int NoAnt = 0;
        cQueue q = new cQueue();
        do{
            System.out.println("");
            System.out.println("MENU PROGRAM QUEUE");
            System.out.println("1. Enqueue");
            System.out.println("2. Dequeue");
            System.out.println("3. Print");
            System.out.println("4. Exit");
            System.out.println("");
            System.out.print("Pilihan : ");
            Pilih = input.nextInt();
            switch(Pilih){
                case 1 :
                    NoAnt++;
                    System.out.println("");
                    System.out.println("ENQUEUE");
                    System.out.print("Masukkan NPM : ");
                    String np = input.next();
                    String no = String.valueOf(NoAnt);
                    cObject b = new cObject(no,np);
                    q.enqueue(b);
                    break;
                case 2 :
                    System.out.println("");
                    System.out.println("DEQUEUE");
                    cObject t = q.dequeue();
                    if(t == null){
                        System.out.println("KOSONG");
                    }else{
                        System.out.println(t.getNPM()+" Keluar");
                    }
                    break;
                case 3 :
                    System.out.println("");
                    System.out.println("PRINT");
                    q.print();
                    break;
                case 4 :
                    System.out.println("");
                    System.out.println("EXIT");
                    System.out.println("Terima Kasih");
                    break;
            }
        }while(Pilih!=4);
    }
}

Source Code cObject :

package pkgQueue;
public class cQueue {
    cObject front, rear;
    int size;
    cQueue(){
        front = rear = null;
        size = 0;
        System.out.println("Objet Queue dibuat...");
    }
    public void enqueue(cObject baru){
        if(rear == null){
            front = rear = baru;
        }else{
            //Jika queue terisi
            rear.next = baru;
            baru.prev = rear;
            rear = baru;
        }
        size++;
        System.out.println("Enqueue Sukses...");
    }
    public cObject dequeue(){
        if(rear == null){
            System.out.println("Queue Kosong...");
            return(null);
        }else if(front.next == null){
            cObject t = front;
            front = rear = null;
            System.out.println("Dequeue Sukses...");
            size--;
            return(t);
        }else{
            cObject t = front.next;
            cObject t2 = null;
            t2.next = null;
            front = t;
            front.prev = null;
            System.out.println("Dequeue Sukses...");
            size--;
            return(t2);
        }
    }
    public void print(){
        System.out.println("Isi Queue "+size+" : ");
        for(cObject t = front; t != null; t = t.next){
            System.out.println(t.getNoAnt()+"\t"+t.getNPM());
        }
        System.out.println("");
    }
}

Source Code cObject:

package pkgQueue;
public class cObject {
    private String NPM;
    private String NoAnt;
    cObject next, prev;
    cObject (String no, String np){
        NoAnt = no;
        NPM   = np;
        System.out.println("Objet "+np+" Dibuat...");
    }
    public String getNoAnt(){
        return NoAnt;
    }
    public String getNPM(){
        return NPM;
    }
    
}