make MergeSort and GeneralCompare typesafe

src/sort/GeneralCompare.java

 package sort;
 
-public interface GeneralCompare {
-	public int compare(Comparable a1, Comparable a2);
+public interface GeneralCompare<T> {
+	public int compare(Comparable<T> a1, Comparable<T> a2);
 }

src/sort/MergeSort.java

@@ -3,11 +3,9 @@ package sort;
 import java.lang.reflect.Array;
 
 public class MergeSort{
-
-	private static Comparable[] aux;
 	
 	public static void main(String[] args) {
-		GeneralCompare b1;
+		GeneralCompare<Integer> b1;
 		b1 = (a1, a2) -> (Integer) a1 - (Integer) a2;
 		Integer[] test = {3, 4, 2, 1, 5, 7, 9, 10, 11};
 		//Integer[] test = {2, 1};
@@ -18,23 +16,24 @@ public class MergeSort{
 		}
 	}
 
-	public static void sort(Comparable[] x, int lo, int hi, GeneralCompare gc) {
-		aux = new Comparable[x.length];
-		sortWrapped(x, lo, hi, gc);
+	public static <T> void sort(Comparable<T>[] x, int lo, int hi, GeneralCompare<T> gc) {
+		Comparable<T>[] aux;
+		aux = (Comparable<T>[]) new Comparable[x.length];
+		sortWrapped(x, lo, hi, gc, aux);
 	}
 	
-	private static void sortWrapped(Comparable[] x, int lo, int hi, GeneralCompare gc) {
+	private static <T> void sortWrapped(Comparable<T>[] x, int lo, int hi, GeneralCompare<T> gc, Comparable<T>[] aux) {
 		int n = hi - lo; 
 		if(n < 1)
 			return;
 		// Recursively sort each half of the array
 		int mid = lo + (n/2);
-		sortWrapped(x, lo, mid, gc);
-		sortWrapped(x, mid+1, hi, gc);
-		merge(x, lo, hi, gc);
+		sortWrapped(x, lo, mid, gc, aux);
+		sortWrapped(x, mid+1, hi, gc, aux);
+		merge(x, lo, hi, gc, aux);
 	}
 
-	private static void merge(Comparable[] x, int lo, int hi, GeneralCompare gc){
+	private static <T> void merge(Comparable<T>[] x, int lo, int hi, GeneralCompare<T> gc, Comparable<T>[] aux){
 
 		int n = hi - lo;
 		int mid = lo + (n/2);
@@ -58,31 +57,5 @@ public class MergeSort{
 			else
 				x[k] = aux[i++];
 		}
-		
-		/*
-		int i = 0;
-		// Merging two sorted arrays
-		while (i <= n) {
-			if (gc.compare(aux[lo], aux[mid]) > 0)
-				x[i++] = aux[mid++]; 
-			else
-				x[i++] = aux[lo++];
-		}
-		*/
-
-
-		/*
-		// Is this portion sorting the aux array? Check
-		for(int k = 1; k <= n; k++){
-			if(i > j-1)
-				x[k] = aux[j++];
-			else if(j > n)
-				x[k] = aux[i++];
-			else if(gc.compare(aux[j+1],aux[1]) < 0)// ?
-				x[k] = aux[j++]; 
-			else 
-				x[k] = aux[i++];
-		}*/
-
 	}
 }