Java: Please don't copy previous incorrect codes posted in this site before!

In this project, the students are required to implement the following algorithms: Insert Sort, Select Sort, Quick Sort, and Merge Sort. One file is given: ProjOne.java. Please study this file to understand what is going on. This file shall not be modified. One file is to implement: MySort.java. In this file, the students must provide the following public interface: public static void insertSort(int [] arr); public static void selectSort(int [] arr); public static void quickSort(int [] arr); public static void mergeSort(int [] arr); The quick sort and merge sort must be implemented by using recursive thinking. So the students may provide the following private static methods: // merge method // merge two sorted portions of given array arr, namely, from start to middle // and from middle + 1 to end into one sorted portion, namely, from start to end private static void merge(int [] arr, int start, int middle, int end); // merge sort recursive version // sort the portion of giving array arr, from begin to end private static void mergeSortRecursive(int [] arr, int begin, int end); // find pivot point for quick sort private static int pivot(int [] arr, int begin, int end); // quick sort recursive version // sort the portion of giving array arr, from begin to end private static void quickSortRecursive(int [] arr, int begin, int end); The student need to have and only have the above public and private static methods in his/her implementation of MySort class. /** ProjOne.java * This is the main function for Project One. * This class is given to students. * * * @version Jan 30, 2019 */ import java.util.*; public class CSCI251ProjOne { public static final int RANGE = 100000; /** * Randomly fill up the given array with integers from 0 to 100000 */ public static void fillArray(int [] arr) { Random randGen = new Random(); for(int i = 0; i < arr.length; i++) arr[i] = randGen.nextInt(RANGE); } /** * copy the content in second array to first array. We assume * two array has same size * @param firstArray the destination of copy action * @param secondArray the source of copy action */ public static void copy(int [] firstArray, int [] secondArray) { for(int i = 0; i < secondArray.length; i++) firstArray[i] = secondArray[i]; } /** * isSorted * @return true if the array is sorted from least to largest * or is sorted from largest to least */ public static boolean isSorted(int [] arr) { if(arr.length <= 1) return true; int index = 0; while(index < arr.length-1 && arr[index] == arr[index+1]) { index++; } // bypass first equal elements if(index == arr.length - 1) return true; // all elements are the same else if(index < arr.length - 1 && arr[index] > arr[index+1]) // possible descend { for(int i = index+2; i < arr.length; i++) if(arr[i] > arr[i-1]) return false; } else // sort for ascend { for(int i = index+2; i < arr.length; i++) if(arr[i] < arr[i-1]) return false; } return true; } /** * test the sort with given array. The test array will not be modified * @param arr The array that is used to test the sort. The array will not be modified * @name The name of sort method that is to be tested */ public static void testSort(int [] arr, String name) { long totalTime = 0; int [] a = new int[arr.length]; copy(a, arr); // copy arr to a // get start time long start = Calendar.getInstance().getTimeInMillis(); if(name.equals("Insert Sort")) MySorts.insertSort(a); else if(name.equals("Select Sort")) MySorts.selectSort(a); else if(name.equals("Quick Sort")) MySorts.quickSort(a); else if(name.equals("Merge Sort")) MySorts.mergeSort(a); long end = Calendar.getInstance().getTimeInMillis(); if(isSorted(a)){ totalTime = end - start; System.out.println("Execution time for " + name + " is: " + totalTime + " milliseconds"); } else System.out.println("The " + name + " did not work properly"); } /** * display the test menu */ public static void displayMenu() { System.out.println("***************************"); System.out.println("* MENU *"); System.out.println("* 1. Fill Array *"); System.out.println("* 2. Select Sort *"); System.out.println("* 3. Insert Sort *"); System.out.println("* 4. Quick Sort *"); System.out.println("* 5. Merge Sort *"); System.out.println("* 6. Quit *"); System.out.println("***************************"); } public static void main(String [] args){ int choice; int [] arr = new int[RANGE]; Scanner input = new Scanner(System.in); do{ displayMenu(); System.out.println("Enter you choice: "); choice = input.nextInt(); switch(choice){ case 1: // generate a new random filled array fillArray(arr); break; case 2: // select sort testSort(arr, "Select Sort"); break; case 3: // insert sort testSort(arr, "Insert Sort"); break; case 4: // quick sort testSort(arr, "Quick Sort"); break; case 5: // merge sort testSort(arr, "Merge Sort"); break; case 6: // quit System.out.println("Make sure that you have good documentation!"); break; default: // wrong choice } }while(choice != 6); } }