Assignment No.11 after correction

2 files changed, 71 insertions, 47 deletions

diff --git a/src/de/fhswf/in/inf/java1/aufgabe11/UPN.java b/src/de/fhswf/in/inf/java1/aufgabe11/UPN.java
index 25b939e..f8938fc 100644
--- a/src/de/fhswf/in/inf/java1/aufgabe11/UPN.java
+++ b/src/de/fhswf/in/inf/java1/aufgabe11/UPN.java
@@ -43,52 +43,43 @@ public class UPN
 
       for (String string : upnString.split("\\s+"))
       {
-         try
-         {
-            upnStack.add(Double.valueOf(string));
-         }
-         catch (NumberFormatException e)
-         {
-            double operand1 = 0;
-            double operand2 = 0;
-            if (upnStack.size() < 2)
-            {
-               throw new IllegalStateException(
-                     "Two operands are needed for an operation.");
-            }
 
-            operand2 = upnStack.pop();
-            operand1 = upnStack.pop();
+         Double[] operands = null;
 
-            switch (string)
-            {
-               case "+":
-                  upnStack.add(operand1 + operand2);
-                  break;
-               case "-":
-                  upnStack.add(operand1 - operand2);
-                  break;
-               case "*":
-                  upnStack.add(operand1 * operand2);
-                  break;
-               case "/":
-                  if (operand2 == 0)
-                  {
-                     throw new IllegalArgumentException("Divisor can't be 0.");
-                  }
-                  upnStack.add(operand1 / operand2);
-                  break;
-               case "%":
-                  if (operand2 == 0)
-                  {
-                     throw new IllegalArgumentException("Divisor can't be 0.");
-                  }
-                  upnStack.add(operand1 % operand2);
-                  break;
-               default:
+         switch (string)
+         {
+            case "+":
+               operands = fetch();
+               upnStack.add(operands[0] + operands[1]);
+               break;
+            case "-":
+               operands = fetch();
+               upnStack.add(operands[0] - operands[1]);
+               break;
+            case "*":
+               operands = fetch();
+               upnStack.add(operands[0] * operands[1]);
+               break;
+            case "/":
+               divisorZero();
+               operands = fetch();
+               upnStack.add(operands[0] / operands[1]);
+               break;
+            case "%":
+               divisorZero();
+               operands = fetch();
+               upnStack.add(operands[0] % operands[1]);
+               break;
+            default:
+               try
+               {
+                  upnStack.add(Double.valueOf(string));
+               }
+               catch (NumberFormatException e)
+               {
                   throw new IllegalArgumentException("String: \"" + string
-                        + "\" is not a valid operator.");
-            }
+                        + "\" is not a valid operator nor a valid operand.");
+               }
          }
       }
    }
@@ -102,9 +93,42 @@ public class UPN
    {
       if (upnStack.empty())
       {
-         throw new IllegalStateException("UPN stack is empty.");
+         throw new IllegalArgumentException("UPN stack is empty.");
       }
       return upnStack.peek();
    }
+   
+   /**
+    * Checks if Divisor will be zero.
+    *
+    */
+   private void divisorZero()
+   {
+      if (upnStack.peek() == 0.0)
+      {
+         throw new IllegalArgumentException("Divisor can't be 0.");
+      }
+   }
+
+   /**
+    * Checks if there are two values on the stack and returns them.
+    *
+    * @return The two top most doubles from the stack.
+    */
+   private Double[] fetch()
+   {
+      if (upnStack.size() < 2)
+      {
+         throw new IllegalArgumentException(
+               "Two operands are needed for an operation.");
+      }
+
+      Double[] ret = new Double[2];
+
+      ret[1] = upnStack.pop();
+      ret[0] = upnStack.pop();
+
+      return ret;
+   }
 
 }
diff --git a/src/de/fhswf/in/inf/java1/aufgabe11/UpnMain.java b/src/de/fhswf/in/inf/java1/aufgabe11/UpnMain.java
index a0f8a00..31ca70d 100644
--- a/src/de/fhswf/in/inf/java1/aufgabe11/UpnMain.java
+++ b/src/de/fhswf/in/inf/java1/aufgabe11/UpnMain.java
@@ -4,7 +4,7 @@
 package de.fhswf.in.inf.java1.aufgabe11;
 
 /**
- * A class that povides a main.
+ * A class that provides a main.
  *
  * @author $Author: $
  * @version $Revision: $, $Date: $ UTC
@@ -18,7 +18,6 @@ public final class UpnMain
     */
    private UpnMain()
    {
-      // TODO Auto-generated constructor stub
    }
 
    /**
@@ -33,7 +32,8 @@ public final class UpnMain
       UPN test = new UPN();
       
       test.calculate("5 3 - 2 * 10 9 - / 10 6 - 8 6 - 2 * / -");
-
+      System.out.println(test.getResult());
+      test.calculate("5 3 - 2 * 10 9 - / 10 6 - 8 6 - 2 * / -");
       System.out.println(test.getResult());
 
    }