First commit

Homework 8/src/grading/WeightedTotalStrategy.java

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+package grading;
+
+import java.util.*;
+
+/**
+ * An implementation GradingStrategy that applies weights to specific grade keys and weighs each
+ * grade before summing a total.
+ */
+public class WeightedTotalStrategy implements GradingStrategy
+{
+  private Map<String, Double> weights;
+
+  /**
+   * Creates a new instance WeightedTotalStrategy.
+   */
+  public WeightedTotalStrategy()
+  {
+  }
+
+  /**
+   * Creates a new instance WeightedTotalStrategy.
+   * 
+   * @param weights
+   *          A map of keys and weights to be applied to the grades during calculation.
+   */
+  public WeightedTotalStrategy(final Map<String, Double> weights)
+  {
+    this.weights = weights;
+  }
+
+  /**
+   * @param key
+   *          The key of the final totaled grade
+   * @param grades
+   *          The list of grades to calculate the final total grade from
+   * @return A new grade representing the total of the weighted grades
+   */
+  public Grade calculate(final String key, final List<Grade> grades) throws SizeException
+  {
+    if (grades == null || grades.isEmpty())
+    {
+      throw new SizeException();
+    }
+
+    Double total = 0.0;
+
+    for (Grade grade : grades)
+    {
+      Double weight = 1.0;
+      if (weights != null && weights.containsKey(grade.getKey()))
+      {
+        Double mapWeight = weights.get(grade.getKey());
+        weight = Math.max(mapWeight, 0.0);
+      }
+
+      total += Missing.doubleValue(grade.getValue()) * weight;
+    }
+
+    return new LeafGrade(key, total);
+  }
+}