Quick sort recursion

Question

this is my version of quick sort
i cant seem to figure out how to make it a recursive code
any line of code that helps me do this, along with an explanation of why it works will be welcomed. Recursion is just too hard to picture inside my head
    public static String[] quickSort (String[] A, int start, int end){
        //if size is 1 return
        if (A.length < 2 ) return A;
        int pivotIndex = start;
            //do the partition
            for (int i=pivotIndex+1; i<end; i++){
                if (compareStrings(A,A[pivotIndex])){
swapString(A, pivotIndex+1, i);
swapString(A, pivotIndex, pivotIndex+1);
pivotIndex++;
return A;

Answer 1

when i take the return type out of the method, aka i make it void, and i write those two lines i am getting a runtime error
this is the code
    public static void quickSort (String[] A, int start, int end){
        //if size is 1 return
        if (A.length < 2 ) return;
        int pivotIndex = start;
            //do the partition
            for (int i=pivotIndex+1; i<end; i++){
                if (compareStrings(A,A[pivotIndex])){
swapString(A, pivotIndex+1, i);
swapString(A, pivotIndex, pivotIndex+1);
pivotIndex++;
quickSort(A, start, pivotIndex);
quickSort(A, pivotIndex+1, end);
this is how i call it
        String[]  data2 = new String[10];
        data2[0]= "5";
        data2[1]= "2";
        data2[2]= "9";
        data2[3]= "7";
        data2[4]="8";
        data2[5]= "0";
        data2[6]="3";
        data2[7]= "1";
        data2[8]="4";
        data2[9]= "6";
        quickSort(data2);
        System.out.println("");
        System.out.println("============================================");
        System.out.println("");
        for (int i=0; i < data.length; i++) {System.out.println(data2);}