Artemis: Refactor methods for efficiency and modern Java practices

app/src/main/java/control/Single.java

@@ -1,7 +1,10 @@
 package control;
+import java.util.stream.IntStream;
+import java.util.Arrays;
 
 import java.util.Vector;
 
+
 public class Single {
   /**
    * This method is used to calculate the sum of the first n natural numbers.
@@ -11,15 +14,7 @@ public class Single {
    * @return The sum of the first n natural numbers.
    */
   public static int sumRange(int n) {
-    int[] arr = new int[n];
-    int sum = 0;
-    for (int i = 0; i < n; i++) {
-      arr[i] = i;
-    }
-    for (int i : arr) {
-      sum += i;
-    }
-    return sum;
+    return (n * (n - 1)) / 2;
   }
 
   /**
@@ -29,13 +24,7 @@ public static int sumRange(int n) {
    * @return The maximum value in the array.
    */
   public static int maxArray(int[] arr) {
-    int max = 0;
-    for (int i : arr) {
-      if (i > max) {
-        max = i;
-      }
-    }
-    return max;
+    return Arrays.stream(arr).max().getAsInt();
   }
 
   /**
@@ -45,13 +34,6 @@ public static int maxArray(int[] arr) {
    * @param m The modulus.
    */
   public static int sumModulus(int n, int m) {
-    Vector<Integer> multiples = new Vector<Integer>();
-    for (int i = 0; i < n; i++) {
-      if (i % m == 0) {
-        multiples.add(i);
-      }
-    }
-
-    return multiples.stream().mapToInt(Integer::valueOf).sum();
+    return IntStream.range(0, n).filter(i -> i % m == 0).sum();
   }
-}
+}