java - index of in Arraylist<ABC> compare with other Arraylist -

i trying find index of element in arraylist based on value of 1 of properties, giving me -1.

//returnabclinklist method returns abc linked list , cannot use index of on linked list trying convert arraylist list<abc> temp=new arraylist<abc>(somemethod.returnabclinklist());       list<xyz> other=new arraylist<xyz>(); 

lets abc has 3 fields (rollnum, name, state) , xyz has 5 fields, 3 of in common abc (rollnum, name, state, secondname, dob). want iterate through 1 list , find each corresponding element in other list, based on rollnum values being same. goal fill out other corresponding fields (name , state). here's tried:

iterator<abc> itr = abclist.iterator(); while(itr.hasnext()){   abc tempabc=itr.next();   int index = xyzlist.indexof(tempabc.rollnum()); //this comes -1 } 

the problem indexof() returning -1. can implementation?

actual working snippet

import java.util.arraylist; import java.util.iterator; import java.util.list;  public class testlists {      public static void main(string[] args){          list<xyz> temp=new arraylist<xyz>();          list<abc> other=new arraylist<abc>();          abc ab=new abc();         abc ab1=new abc();         ab.rollnum=111;         ab.name="mak";         other.add(ab);          ab1.rollnum=222;         ab1.name="dak";         other.add(ab1);          xyz abd=new xyz();         xyz abd1=new xyz();          abd1.namedb="mak";         abd1.rollnumdb=111;         temp.add(abd1);          abd.namedb="ponty";         abd.rollnumdb=456;         temp.add(abd);           iterator<xyz> itr=temp.iterator();             while(itr.hasnext()){             xyz tempxyz=itr.next();             int index=other.indexof(tempxyz.getrollnumdb()); //this comes -1             other.get(index) //get data             //add more values tempxyz              });     } } 

pojo

public class abc {      int rollnum;     string name;     string state;     public int getrollnum() {         return rollnum;     }     public void setrollnum(int rollnum) {         this.rollnum = rollnum;     }     public string getname() {         return name;     }     public void setname(string name) {         this.name = name;     }      }     public string getstate() {         return name;     }     public void setstate(string name) {         this.name = name;     }  } 

note: tried implementing equals in xyz pojo still no luck

the argument indexof hidden inside xyz object instance, not of type xyz. in case have iterate through xyz list, rollnum out of it, , compare.

in general i'd recommend having @ map. save xyz elements rollnum key, somemap.get(rollnum) gives corresponding xyz element.