Java-How to swap 2 array elements and use toString to output each swap of shell-sort?

I'm still very new to Java and this is an assignment for school where I'm to create a ShellSort class and driver class. The ShellSort class should create and populate an array of n size, and contains a shell sort method using the following pseudo-code:

This is the code I have so far:

import java.util.*;

public class ShellArray {
    int array[] = null;
    int size=0;
    Random random = new Random();
    int gap = 0;

    public ShellArray (int size) {
        this.size = size;

        array=new int[size];
        for (int i = 0; i<size; i++) {
            this.array[i]=random.nextInt(100);
        }


        System.out.println("Your array is: ");
        for(int i=0; i<size;i++) {
            System.out.print(" " +array[i] + " ");
        }
    }


public int[] shellSort(int size) {

        gap = size/2;

        do {
            boolean swapflag = true;
            do {
                swapflag = false;
                for (int s = 0; s<(size-gap);s++) {
                    if (array[s] > array[s+gap]) {

                        //swap array[s] with array[s+gap]

                        swapflag = true;

                        }
                    }
                }
            while (swapflag != false);
        }while (gap>0);

        gap = gap/2;
    }


    public String toString () {

         //to output array results of each swap
    }

}

I'm lost as to how to swap array[s] with array[s+gap] and how to use toString to output array at each swap.

I've tried using a "temp" variable to put array[s] in, so I can put array[s+gap] into array[s]'s index, but I received "ShellArray@7c53a9eb" error?

Any help will be much appreciated! Thank you.

1. To print your array, use System.out.println(Arrays.toString(array))

2. To swap array element,

   if (array[s] > array[s + gap]) { int temp = array[s]; array[s] = array[s + gap]; array[s + gap] = temp; // swap array[s] with array[s+gap] swapflag = true; }

In addition, it seems gap = gap/2; is should be inside the first do while loop.