/** This class sorts an array, using the merge sort algorithm. */ public class MergeSorter { private int[] a; /** Constructs a merge sorter. @param anArray the array to sort */ public MergeSorter(int[] anArray) { a = anArray; } /** Sorts the array managed by this merge sorter. */ public void sort() { if (a.length <= 1) return; int[] first = new int[a.length / 2]; int[] second = new int[a.length - first.length]; // Copy the first half of a into first, the second half into second for (int i = 0; i < first.length; i++) { first[i] = a[i]; } for (int i = 0; i < second.length; i++) { second[i] = a[first.length + i]; } MergeSorter firstSorter = new MergeSorter(first); MergeSorter secondSorter = new MergeSorter(second); firstSorter.sort(); secondSorter.sort(); merge(first, second); } /** Merges two sorted arrays into the array managed by this merge sorter. @param first the first sorted array @param second the second sorted array */ private void merge(int[] first, int[] second) { int iFirst = 0; // Next element to consider in the first array int iSecond = 0; // Next element to consider in the second array int j = 0; // Next open position in a // As long as neither iFirst nor iSecond is past the end, move // the smaller element into a while (iFirst < first.length && iSecond < second.length) { if (first[iFirst] < second[iSecond]) { a[j] = first[iFirst]; iFirst++; } else { a[j] = second[iSecond]; iSecond++; } j++; } // Note that only one of the two loops below copies entries // Copy any remaining entries of the first array while (iFirst < first.length) { a[j] = first[iFirst]; iFirst++; j++; } // Copy any remaining entries of the second half while (iSecond < second.length) { a[j] = second[iSecond]; iSecond++; j++; } } }
Here is the tester class provided:
import java.util.Arrays; /** This class tests the MergeSorter class to sort an array of strings. */ public class MergeSorterTester { public static void main(String[] args) { String[] a = { "Able", "was", "I", "ere", "I", "saw", "Elba" }; MergeSorter m = new MergeSorter(a); m.sort(); System.out.println(Arrays.toString(a)); System.out.println("Expected: [Able, Elba, I, I, ere, saw, was]"); } }
The error I keep getting is that on the tester class on line 12:
MergeSorter m = new MergeSorter(a);
I keep getting the error: The constructor MergeSorter(String []) is undefined
I'm sorta new to programming so I would really appreciate any help. Thanks.