Iterator Pattern

Iterator Pattern: provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation.

Example

Spare.java

package com.iteratorpattern.example;

public class Spare {
 private String name;
 private String description;
 private float price;
 
 public Spare(String name, String description, float price) {
  this.name = name;
  this.description = description;
  this.price = price;
 }
 public String getName() {
  return name;
 }
 public String getDescription() {
  return description;
 }
 public float getPrice() {
  return price;
 }
}

BikeSpare.java

package com.iteratorpattern.example;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class BikeSpare implements SpareList {
 List spareList = new ArrayList<>();

 public BikeSpare() {
  spareList.add(new Spare("Head Light Assembly", "Head Light holder and blub set", 700));
  spareList.add(new Spare("Piston", "Piston with bearing", 1500));
  spareList.add(new Spare("Tyres", "Front and back tyres", 1200));
 }

 @Override
 public Iterator createIterator() {
  return new BikeSpareItearator(spareList);
 }

}

CarSpare.java

package com.iteratorpattern.example;

import java.util.Iterator;

public class CarSpare implements SpareList {
 public final int MAXITEMS = 3;
 Spare[] spareItems = new Spare[MAXITEMS];
 public int noofItems = 0;
 
 public CarSpare(){
  addItem(new Spare("Bumpers", "Front and Rear Bumper Assembly", 4000));
  addItem(new Spare("CrankShaft", "CrankShaft with bearings", 2500));
  addItem(new Spare("audio player", "audio player with usb and aux connectivity", 1000));
 }
 
 public void addItem(Spare spare){
  if (noofItems >= MAXITEMS) {
   System.out.println("can't add more spares");
  } else {
   spareItems[noofItems] = spare;
   noofItems++;
  }
 }
 
 public Iterator createIterator(){
  return new CarSpareIterator(spareItems);
 }

}

TruckSpare.java

package com.iteratorpattern.example;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class TruckSpare implements SpareList {
 Map spareList = new HashMap<>();

 public TruckSpare() {
  String name = "Front Grill";
  spareList.put(name,new Spare(name, "Front Grill Assembly", 3000));
  name = "Horn Assembly";
  spareList.put(name,new Spare(name, "Horn with Holders Assembly", 1500));
  name = "Seat Covers";
  spareList.put(name,new Spare(name, "set of seat covers", 1200));
 }

 @Override
 public Iterator createIterator() {
  return spareList.values().iterator();
 }

}

SpareList.java

package com.iteratorpattern.example;
import java.util.Iterator;

public interface SpareList {
 public Iterator createIterator();
}

BikeSpareItearator.java

package com.iteratorpattern.example;

import java.util.Iterator;
import java.util.List;

public class BikeSpareItearator implements Iterator {
 
 List sparesList;
 int position;

 public BikeSpareItearator(List sparesList) {
  this.sparesList = sparesList;
 }

 @Override
 public boolean hasNext() {
  if(position>=sparesList.size()){
   return false;
  }else{
   return true;
  }
 }

 @Override
 public Spare next() {
  Spare spareItem = sparesList.get(position);
  position++;
  return spareItem;
 }

}

CarSpareItearator.java

package com.iteratorpattern.example;

import java.util.Iterator;

public class CarSpareIterator implements Iterator {
 
 Spare[] spareItems;
 int position;


 public CarSpareIterator(Spare[] spareItems) {
  this.spareItems = spareItems;
 }

 @Override
 public boolean hasNext() {
  if(position>=spareItems.length||spareItems[position]==null){
   return false;
  }else{
   return true;
  }
 }

 @Override
 public Spare next() {
  Spare spareItem = spareItems[position];
  position++;
  return spareItem;
 }

}

Dealer.java

package com.iteratorpattern.example;

import java.util.Iterator;
import java.util.List;

public class Dealer {
 private List spareList;

 public Dealer(List spareList) {
  this.spareList = spareList;
 }
 
 public void listMenu(){
  for (SpareList spare : spareList) {
   listMenu(spare.createIterator());
  }
 }
 
 public void listMenu(Iterator iterator){
  while (iterator.hasNext()) {
   Spare spare = (Spare) iterator.next();
   System.out.format("Item Name %s with Description %s is of price %.2f \n", spare.getName(), spare.getDescription(), spare.getPrice());
  }
 }
}

GarageTestDrive.java

package com.iteratorpattern.example;

import java.util.ArrayList;
import java.util.List;

public class GarageTestDrive {
 public static void main(String[] args) {
  List spareList = new ArrayList<>();
  spareList.add(new BikeSpare());
  spareList.add(new CarSpare());
  spareList.add(new TruckSpare());
  Dealer dealer = new Dealer(spareList);
  dealer.listMenu();
 }
}

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