Add another Java solution

Author: bcjordan

find_uncoupled_int/solutions/Solution.java

@@ -0,0 +1,34 @@
+class Solution {
+  public static int findUncoupled(int[] integers) {
+    int allXored = 0;
+    for (int i : integers) {
+      allXored ^= i;
+    }
+    return allXored;
+  }
+
+  public static int findUncoupledSet(int[] integers) {
+    Set<Integer> seen = new HashSet<Integer>();
+
+    for (int i : integers) {
+      if (seen.contains(i)) {
+        seen.remove(i);
+      } else {
+        seen.add(i);
+      }
+    }
+
+    for (int uncoupled : seen) {
+      // Will be only one
+      return uncoupled;
+    }
+
+    throw new IllegalArgumentException("Does not contain uncoupled integer.");
+  }
+
+  public static void main(String[] args) {
+    int[] ints = new int[] { 1, 1, 2, 2, 8 };
+    System.out.println(findUncoupled(ints));
+    System.out.println(findUncoupledSet(ints));
+  }
+}