Add all the A tasks

Task/Accumulator-factory/Java/accumulator-factory-1.java

@@ -0,0 +1,16 @@
+public class Accumulator {
+    private double sum;
+    public Accumulator(double sum0) {
+        sum = sum0;
+    }
+    public double call(double n) {
+        return sum += n;
+    }
+
+    public static void main(String[] args) {
+        Accumulator x = new Accumulator(1);
+        x.call(5);
+        System.out.println(new Accumulator(3));
+        System.out.println(x.call(2.3));
+    }
+}