From 02e042bc2fe8e5f308d7436cffea9494153fb3bc Mon Sep 17 00:00:00 2001
From: Schankula Christopher <schankuc@mcmaster.ca>
Date: Fri, 2 Mar 2018 16:45:25 -0500
Subject: [PATCH] make MergeSort and GeneralCompare typesafe
---
src/sort/GeneralCompare.java | 4 +--
src/sort/MergeSort.java | 47 ++++++++----------------------------
2 files changed, 12 insertions(+), 39 deletions(-)
diff --git a/src/sort/GeneralCompare.java b/src/sort/GeneralCompare.java
index b5d51af..72b8e86 100644
--- a/src/sort/GeneralCompare.java
+++ b/src/sort/GeneralCompare.java
@@ -1,5 +1,5 @@
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);
}
diff --git a/src/sort/MergeSort.java b/src/sort/MergeSort.java
index a764c57..2927578 100644
--- a/src/sort/MergeSort.java
+++ b/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++];
- }*/
-
}
}
--
GitLab