Add all the A tasks

Task/Averages-Simple-moving-average/Java/averages-simple-moving-average.java

@@ -0,0 +1,38 @@
+import java.util.LinkedList;
+import java.util.Queue;
+public class MovingAverage {
+    private final Queue<Double> window = new LinkedList<Double>();
+    private final int period;
+    private double sum;
+
+    public MovingAverage(int period) {
+        assert period > 0 : "Period must be a positive integer";
+        this.period = period;
+    }
+
+    public void newNum(double num) {
+        sum += num;
+        window.add(num);
+        if (window.size() > period) {
+            sum -= window.remove();
+        }
+    }
+
+    public double getAvg() {
+        if (window.isEmpty()) return 0; // technically the average is undefined
+        return sum / window.size();
+    }
+
+    public static void main(String[] args) {
+        double[] testData = {1,2,3,4,5,5,4,3,2,1};
+        int[] windowSizes = {3,5};
+        for (int windSize : windowSizes) {
+            MovingAverage ma = new MovingAverage(windSize);
+            for (double x : testData) {
+                ma.newNum(x);
+                System.out.println("Next number = " + x + ", SMA = " + ma.getAvg());
+            }
+            System.out.println();
+        }
+    }
+}