Java OOP: referencing subclass object -

i have arrayclass , mergesortarray extends it. , mergesortarray contains mergesort() method. however, since used super call constructor superclass, not know how refer mergesortarray (the subclass object / array) , pass parameter in mergesort method. in fact, feasible ? know can in non- oop way. however, keen know how in oop way.

please correct me if have said incorrect, new java , want learn more it.

// arrayclass object     import java.util.*;     import java.io.*;     import java.math.*;  public class arrayclass{     public int[] input_array;     public int nelems;      public arrayclass(int max){         input_array = new int [max];         nelems = 0;     }      public void insert(int value){         input_array[nelems++] = value;     }      public void display(){         for(int j = 0; j < nelems; j++){             system.out.print(input_array[j] + " ");         }         system.out.println("");     }  }    import java.io.*; import java.util.*; import java.math.*;  class mergesortarray extends arrayclass{      public mergesortarray(int max){         super(max);     }      public void methodone(){         int[] output_array = new int[super.nelems];         mergesort( // ************* // ,output_array,0, super.nelems -1);       }        ................ } 

i not sure should put replace ****** such can pass mergesortarray parameter mergesort method.

there isn't mergesortarray. inherit input_array (and no need super.nelems inherit too),

 mergesort( input_array, output_array, 0, nelems - 1); 

your sub-class inherit protected or greater visibility (not private), arrayclass gives both public fields

public int[] input_array; public int nelems; 

they should protected , have accessor methods (getters).

protected int[] input_array; protected int nelems; public int size() {   return nelems; } public int[] getinputarray() {   return input_array; }