SortTest.java with ALL SORTS COMPLETE

public class SortTest{

  public static void main(String args[]){
    int theArray[] = {4,2,5,1,3,18,0,9,6};
    //selectionSort(theArray);
    //insertionSort(theArray);
    mergeSort(theArray, 0, theArray.length - 1);
    for(int j = 0; j < theArray.length; j++){
      System.out.print(theArray[j] + " ");
    }
    System.out.println(" ");
  }

  public static void selectionSort(int a[ ]){
    int minIndex, min;
    for(int i = 0; i < a.length - 1; i++){//keeps track of swap position
      minIndex = i;
      min = a[i];
      for(int j = i + 1; j < a.length; j++){//finds the minIndex
        if(a[j] < min){
          minIndex = j;
          min = a[j];
        }
      }
      //swap after finding min
      int temp = a[i];
      a[i] = a[minIndex];
      a[minIndex] = temp;
    }
  }

  public static void insertionSort(int a[ ]){
    int itemToInsert, j;
    boolean keepGoing;
    //On kth pass, insert item k into its correct position
    //among the first k elements in the array
    for(int k = 1; k < a.length; k++){
      //Go backwards through the sorted part of the array
      //looking for the correct spot for the kth element
      itemToInsert = a[k];
      j = k - 1;
      keepGoing = true;
      while( j >= 0 && keepGoing == true ){
        if(itemToInsert < a[j]){
          //If element is less than a[j], shift to the right to make room
          a[j+1] = a[j];
          j--;
          if( j == -1 ){//If we are at the leftmost element, insert
            a[0] = itemToInsert;
          }
        }
        else{//The correct place for the element is found, insert
          keepGoing = false;
          a[j+1] = itemToInsert;
        }
      }
    }
  }

  //This does the initial splitting step
  public static void mergeSort(int a[ ], int left, int right){
    if(right == left) return;
    int middle = (left + right) / 2;
    mergeSort(a, left, middle);//recursion (left half)
    mergeSort(a, middle + 1, right);//recursion (right half)
    merge(a, left, middle, right);//seen soon
  }

  //This does the final step of merging
  public static void merge(int a[], int left, int middle, int right){
    //Temporary array to build the merged list
    int tempArr[] = new int[right - left + 1];

    int index1 = left;
    int index2 = middle + 1;
    int indx = 0;

    //Loop until one of the sublists is finished, adding the smaller
    //of the first elements of each sublist to the merged list
    while(index1 <= middle && index2 <= right){
      if(a[index1] < a[index2]){
        tempArr[indx] = a[index1];
        index1++;
      }
      else{
        tempArr[indx] = a[index2];
        index2++;
      }
      indx++;
    }

    //Add to the merged "list" the remaining elements of whichever
    //"sublist" is not yet finished
    while( index1 <= middle ){
      tempArr[indx] = a[index1];
      index1++;
      indx++;
    }
    while( index2 <= right){
      tempArr[indx] = a[index2];
      index2++;
      indx++;
    }

    //Copy the merged list from the tempArr into the a array
    for( indx = 0; indx < tempArr.length; indx++ ){
      a[left + indx ] = tempArr[indx];
    }

  }
}