Java, add a value to list<pair> -

i'm struggling getting value list<integer> list<pair<integer,integer>>. pair class written me enclose. ideas how it? prefer make deep copy instead of copying references. believe getting value list works fine, problem inserting value listpair.

i'd grateful suggestions.

public class pair<l,r>{     private l key;     private r value;       public pair(l key, r value)     {         this.key = key;         this.value = value;     }      public l getl() {return key;}     public r getr() {return value;}     public void setl(l key) {this.key = key;}     public void setr(r value) {this.value = value;} }  it's how create list(in main()) send function creatematrix list<integer> numberscopy = new arraylist<integer>();      public static void creatematrix(list<integer> list,list<list<pair<integer,integer>>> matrix)     {                collections.sort(list); //sortuje listę         collections.reverse(list); //odwraca kolejnosc         int key = 0;         list<pair<integer,integer>> listpair = new arraylist<pair<integer,integer>>();         for(int i=0;i<list.size();i++)         {             listpair.setr(i) = list.get(i); //elements of list should saved value in pair<integer, integer>         }  } 

for me map.entry<k,v> implementation can call put(k key, v value) function.

https://docs.oracle.com/javase/7/docs/api/java/util/map.html