Thread: Simple inventory System. Sometimes it doesn't update my added book.

import java.util.*;
   public class S10105810_Assignment
   {
      public static void main(String[] args)
      {
         int[] code = new int[20];			// array for codes
         String[] title = new String[20];	// array for booktitles
         double[] price = new double[20];	// array for price of books
         int[] qty = new int[20];			// array for quantity of books
         int count = 0;	
         int choice= 1;                   
         int number =0; 
         int search=0;                   // search when there user enter 1
         int idex=-1;                     // return if search cannot be found
         int key;				              // To enter the book that user want to find
			int serialnum=1;                //  To indicate the s/no of the book that is out of stock. Serial num always at 1 
 
         Scanner input = new Scanner(System.in);
         while(choice != 0)                       // when choice is not 0 to exit. 
         {
            System.out.println("MENU " + "\n" + "====");
            System.out.println("1) Display All Books" + "\n2) Display books that are out of stock" + "\n3)Add new book"+ "\n4)Update Quantity of a book"+ "\n5)Display Lowest Quantity"+ "\n6)Search a book"+ "\n7)Remove a Book"+ "\n0)Exit");
            System.out.print("Enter your option : " );
            choice = input.nextInt();
 
            if(choice==1)
            {
               System.out.println("Option 1. Display all books");
               if(count<=6)
               {
                  if(number>0)
                  {
                   System.out.println("S/No"+"\t"+"Code"+"\t"+"Price"+"\t"+"Quantity"+"\t"+"Title"+"\n----"+"\t"+ "----"+"\t"+ "-----"+"\t"+"-----"+"\t"+"\t"+"-----");
                   for(int i=1;i<count+1;i++)
                   {
                    System.out.println(i + "\t" + code[i-1] + "\t" + price[i-1] + "\t" + qty[i-1] + "\t" +"\t"+ title[i-1]);
                   }
					    if(idex!=-1)
						 {
						  RemovedBook(code,title,price,qty,count,number);
						 }
                  }
                  else
                  {
						 if(idex==-1)
						 {
                    count = initialization(code,title,price,qty);
                    System.out.println("S/No"+"\t"+"Code"+"\t"+"Price"+"\t"+"Quantity"+"\t"+"Title"+"\n----"+"\t"+ "----"+"\t"+ "-----"+"\t"+"-----"+"\t"+"\t"+"-----");
                      for(int i=1;i<count+1;i++)
                    {
                     System.out.println(i + "\t" + code[i-1] + "\t" + price[i-1] + "\t" + qty[i-1] + "\t" +"\t"+ title[i-1]);
                    }
						 }
						 if(idex!=-1)
						 {
						  RemovedBook(code,title,price,qty,count,number);
						 }
                  }
 
               }
               if(count>6)
               {
                  if(number>0)
                  {
                     System.out.println("S/No"+"\t"+"Code"+"\t"+"Price"+"\t"+"Quantity"+"\t"+"Title"+"\n----"+"\t"+ "----"+"\t"+ "-----"+"\t"+"-----"+"\t"+"\t"+"-----");
                     for(int i=1;i<count+1;i++)
                     {
                        System.out.println(i + "\t" + code[i-1] + "\t" + price[i-1] + "\t" + qty[i-1] + "\t" +"\t"+ title[i-1]);
                     }
							if(idex!=-1)
							{
							RemovedBook(code,title,price,qty,count,number);
							}
                  }
                  else
                  {
                     System.out.println("S/No"+"\t"+"Code"+"\t"+"Price"+"\t"+"Quantity"+"\t"+"Title"+"\n----"+"\t"+ "----"+"\t"+ "-----"+"\t"+"-----"+"\t"+"\t"+"-----");
                     for(int i=1;i<count+1;i++)
                     {
                        System.out.println(i + "\t" + code[i-1] + "\t" + price[i-1] + "\t" + qty[i-1] + "\t" +"\t"+ title[i-1]);
                     }
							if(idex!=-1)
							{
							RemovedBook(code,title,price,qty,count,number);
							}
                  }
               }
 
            }
            if(choice==2)
            {
              OutOfStock(code,title,price,qty,count,serialnum);
            }
            if(choice==3)
            {
               count=NewBook(code,title,price,qty,count);
            }
            if(choice==4)
            {
               number=updateQuantity(code,title,price,qty,count,number);
            }
            if(choice==5)
            {
               lowestQuantity(code,title,price,qty,count);
            }
 
            if(choice==6)
            {
				   System.out.println("Option 6. Searching for a book");
               System.out.print("Enter 1 if you wish to proceed with searching for a particular book(0 to skip): ");
               search= input.nextInt();
               while(search==1)
               {
                  System.out.print("Enter the book you want to search for: ");
                  key= input.nextInt();
                  idex = searchingforBook(code,key,count);
                  if(idex == -1)
                  {
                     System.out.println("No such book Exist");
                  }
                  else
                  {
						   System.out.println("S/No"+"\t"+"Code"+"\t"+"Price"+"\t"+"Quantity"+"\t"+"Title"+"\n----"+"\t"+ "----"+"\t"+ "-----"+"\t"+"-----"+"\t"+"\t"+"-----");
							System.out.println(idex + "\t" + code[idex-1] + "\t" + price[idex-1] + "\t" + qty[idex-1] + "\t" +"\t"+ title[idex-1]);
                  }
                  System.out.print("Do you want to continue searching books? 1 to continue, 0 to end: ");
                  search=input.nextInt();
               }	 	
            }
            if(choice==7)
            {
				   System.out.println("Option 7. Removing a book");
               System.out.print("Enter 1 if you wish to proceed with removing a particular book(0 to skip): ");
               search= input.nextInt();
               while(search==1)
               {
                  System.out.print("Enter the book you want to remove: ");
                  key= input.nextInt();
                  idex = removingBook(code,key,count);
                  if(idex == -1)
                  {
                     System.out.println("No such book");
                  }
                  else
                  {
			            code[idex-1]=0;
			            qty[idex-1]=0;
			             title[idex-1]="";
			             price[idex-1]=0;
			             System.out.println("Book of Serial no."+(idex)+" is Removed.");
 
                  }
                  System.out.print("If Continue removing books? Enter 1 to continue or 0 to End Removing book: ");
                  search=input.nextInt();
               }	 	
            }
 
         }				
      }
 
      public static int initialization(int[] code, String[] title, double[] price, int[] qty)
      {
         code[0] = 9877;
         title[0] = "Awaken The Giant Within";
         price[0] = 19.75;
         qty[0] = 6;
         code[1] = 9965;
         title[1] = "Being Happy!";
         price[1] = 17.33;
         qty[1] = 9;
         code[2] = 9126;
         title[2] = "Chicken Soup For The Teenage Soul";
         price[2] = 21.54;
         qty[2] = 0;
         code[3] = 9429;
         title[3] = "Dealing with People You Can't Stand";
         price[3] = 24.03;
         qty[3] = 3;
         code[4] = 9101;
         title[4] = "Emotional Intelligence";
         price[4] = 16.33;
         qty[4] = 11;
         code[5] = 9222;
         title[5] = "Follow Your Heart";
         price[5] = 21.09;
         qty[5] = 15;
         return 6;
      }
 
      public static void OutOfStock (int[] code, String[] title, double[] price, int[] qty, int count, int serialnum)
      {
         System.out.println("Option 2.Display books out of stock");
         System.out.println("S/No"+"\t"+"Code"+"\t"+"Price"+"\t"+"Quantity"+"\t"+"Title"+"\n----"+"\t"+ "----"+"\t"+ "-----"+"\t"+"-----"+"\t"+"\t"+"-----");
         for(int i=1; i<count; i++)
         {
            if(qty[i-1]==0)
            {
               System.out.println(serialnum + "\t" + code[i-1] + "\t" + price[i-1] + "\t" + qty[i-1] + "\t" +"\t"+ title[i-1]);
            }
         }
      }
      public static int NewBook (int[] code, String[] title, double[] price, int[] qty,int count)
      {
         int num=0;
         Scanner input = new Scanner(System.in);
         System.out.print("Enter 1 to enter book or 0 to exit adding book menu:");
         num = input.nextInt();
         while(num==1)
         {
            System.out.println("Option 3. Add new book");
            System.out.print("Enter a new code: ");
            code[count] = input.nextInt();
            input.nextLine();
            System.out.print("Enter a new title: ");
            title[count] = input.nextLine();
            System.out.print("Enter a new price: ");
            price[count] = input.nextDouble();
            System.out.print("Enter a new quantity: ");
            qty[count] = input.nextInt();
            count++;
            System.out.println("One book added");
 
            System.out.print("Do you want to continue? 1 for Yes, 0 for no");
            num = input.nextInt();
         }
         return count;
      }
      public static int updateQuantity (int[] code, String[] title, double[] price, int[] qty,int count, int num2)
      {
         System.out.println("Option 4. Update quantity");
         int quantity=0;
         Scanner input = new Scanner(System.in);
         System.out.println("S/No"+"\t"+"Code"+"\t"+"Price"+"\t"+"Quantity"+"\t"+"Title"+"\n----"+"\t"+ "----"+"\t"+ "-----"+"\t"+"-----"+"\t"+"\t"+"-----");
         for(int i=1;i<count+1;i++)
         {
          System.out.println(i + "\t" + code[i-1] + "\t" + price[i-1] + "\t" + qty[i-1] + "\t" +"\t"+ title[i-1]);
         }
         System.out.print("Enter the Serial Number of the book to update the quantity: ");
         num2=input.nextInt();
         System.out.print("Enter quantity to increase or decrease: ");
         quantity=input.nextInt();
         qty[num2-1] = qty[num2-1] + quantity;
         System.out.println("Quantity updated");
 
         return num2;
      }
      public static void lowestQuantity (int[] code, String[] title, double[] price, int[] qty,int count)
      {
		   System.out.println("Option 5. Lowest quantity");
         int lowestquantity = qty[0];
         String bookTitle="";
         for (int i=1;i<count+1;i++)
         {
            if (qty[i]<lowestquantity)
            {
               lowestquantity=qty[i];
               bookTitle=title[i];
            }
         }
         System.out.println("Lowest quantity book is "+bookTitle+" at "+lowestquantity);
      }
      public static int searchingforBook (int[] code,int searchKey,int count)
      {
         for(int i=1;i<count+1;i++)
         { 
            if(code[i]==searchKey)
            {
               return i+1;
            }
         }
         return -1;
      }
      public static int removingBook (int[] code,int searchKey,int count)
      {
         for(int i=1;i<count+1;i++)
         { 
            if(code[i]==searchKey)
            {
               return i+1;
            }
         }
         return -1;
      }
		public static void RemovedBook(int[] code, String[] title, double[] price, int[] qty,int count,int num2)
		{
	   System.out.println("S/No"+"\t"+"Code"+"\t"+"Price"+"\t"+"Quantity"+"\t"+"Title"+"\n----"+"\t"+ "----"+"\t"+ "-----"+"\t"+"-----"+"\t"+"\t"+"-----");
       for(int i=1;i<count+1;i++)
       {
        System.out.println(i + "\t" + code[i-1] + "\t" + price[i-1] + "\t" + qty[i-1] + "\t" +"\t"+ title[i-1]);
       }
		}
 
   }

Firstly, whenever you add a book, it should always display the serial number as well as the code,title,price and quantity. However, it doesn't show up sometimes when i try to add a book. The book isn't added into the array. I tried to debug, but i can't seem to find the problem. The debugger isn't showing any problems. Moreover, if i try to add a book with price=0 and quantity =0, it doesn't show up too.

That is WAY too much code for us to wade through. Please read the link in my signature on asking questions the smart way. Code you post should be in the form of an SSCCE, and you should very clearly state what's happening and what you expected to happen. Have you run through this with a debugger, or with a piece of paper and a pencil? Where does the code's behavior differ from what you thought it would do?

You forgot the highlight tags. I added them for you this time.

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cccccccccccccccccccc . thanks

cccccccccccccccccccccccccccc. thank you