java - How can I correctly remove an Object from ArrayList? -

i’m trying remove object arraylist. each item object has 3 attributes; 1. itemnum 2. info 3. cost. have 3 classes, 1. item class defines single items stored in catalog. 2. catalog class maintains list of item objects. 3 client class w/main method. have sets , gets in item class , have arraylist in catalog. in client, have prompt “enter in itemnum remove. how correctly remove item object arraylist based on search itemnum? below code , i’ve tried far.

 public class item   {  private int itemnum;   private string info;   private double cost;   private int itemnum;      public item()   {   //start constructor      itemnum = 0;   //default values      info = "x";      cost = 0;   }   //end constructor    public catalogitem(int newitemnum, string newinfo, double newcost)   {   //start overload constructor      this.itemnum = newitemnum;      this.info = newinfo;      this.cost = newcost;   }   //end overload constructor 

//below set/gets itemnum. have sets/gets cost , info, choose not include space

  public int getitemnum()   {   //start itemnum accessor      return itemnum;    }   //end getitemnum    public void setitemnum(int newitemnum)   {   //start itemnum mutator      this.itemnum = newitemnum;   }   //end setitemnum   }   //end item class    public boolean equals(catalogitem obj)   {   //start equals      if (itemid == obj.itemid)         return true;      else         return false;   }   //end equals 

//below catalog class

 import java.util.*;    public class catalog  {   //start class   private arraylist<catalogitem> listofobjects = new arraylist<catalogitem>(100);   //creates arraylist   item newitem = new item(newitemnum, newinfo, newcost);       public void remove(int id)   {   //start remove      int item = id;       (int index = 0; index < listofobjects.size();        index++)         if (newitem.getitemid() == item)   //if item in inventory matches item number passed           listofobjects.remove(index);  //removes based on index, i’ve tried listofobjects.remove(item);     /*   i’ve tried enhanced loop      (catalogitem obj : listofobjects)         if (newitem.getitemid() == item)            listofobjects.remove(newitem);         */     }   //end remove 

}

//below main. receives input user regarding itemnum, info, , cost

 import java.util.*;   //allows use of scanner class     public class client   {   //start client class    public static void main(string[] args)   {   //start main      catalog serv = new catalog();   //creates instance of catalog class      scanner scan = new scanner(system.in);   //creates instance of scanner class called scan               system.out.print("\nenter in item id want remove: ");                 id = scan.nextint();               serv.remove(id);   //sends id catalog class removed  }   //end main  }   //end class 

it compiles fine, doesn't remove based on found index. great.

override equals method in item class. can use itemnum check equality of objects in equals method.

then use arraylist remove(object o) method delete object. remove method uses equals internally find object removed.

edit:

you not overriding equals method properly, here right signature , implementation:

@override public boolean equals(object obj) {     if (this == obj)         return true;     if (obj == null)         return false;     if (getclass() != obj.getclass())         return false;     item other = (item) obj;     if (itemnum != other.itemnum)         return false;     return true; }