Assignment No.12 implements interface and abstract classes

1 files changed, 51 insertions, 0 deletions

diff --git a/src/de/fhswf/in/inf/java1/aufgabe12/BinaryOperator.java b/src/de/fhswf/in/inf/java1/aufgabe12/BinaryOperator.java
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index 0000000..ef007bd
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+++ b/src/de/fhswf/in/inf/java1/aufgabe12/BinaryOperator.java
@@ -0,0 +1,51 @@
+/**

+ * 

+ */

+package de.fhswf.in.inf.java1.aufgabe12;

+

+import java.util.Stack;

+

+/**

+ * An abstract class for calculations with unary operators.

+ *

+ * @author $Author: $

+ * @version $Revision: $, $Date: $ UTC

+ */

+public abstract class BinaryOperator implements Operator

+{

+   /*

+    * (non-Javadoc)

+    * 

+    * @see de.fhswf.in.inf.java1.aufgabe12.Operator#eval(java.util.Stack)

+    */

+   @Override

+   public final void eval(Stack<Double> stack)

+   {

+      if (stack == null)

+      {

+         throw new IllegalArgumentException("Stack must not be null.");

+      }

+

+      if (stack.size() < 2)

+      {

+         throw new IllegalArgumentException(

+               "Unary operation requires one operand.");

+      }

+

+      double d2 = stack.pop();

+      double d1 = stack.pop();

+

+      stack.push(eval(d1, d2));

+   }

+

+   /**

+    * This class implements the calculation.

+    *

+    * @param d1

+    *           The first operator.

+    * @param d2

+    *           The second operator.

+    * @return The result of the calculation.

+    */

+   abstract double eval(double d1, double d2);

+}