From 7451194aaf573e50eb04849d754b5bc8c0cba05b Mon Sep 17 00:00:00 2001
From: Denis Molony <dmolony@iinet.net.au>
Date: Wed, 1 Mar 2017 07:39:26 +1100
Subject: [PATCH] Value.calculate returns void

---
 .../bytezone/diskbrowser/visicalc/Abs.java    |  4 +-
 .../diskbrowser/visicalc/AbstractValue.java   | 43 +++++-----
 .../bytezone/diskbrowser/visicalc/And.java    |  5 +-
 .../diskbrowser/visicalc/Average.java         |  4 +-
 .../bytezone/diskbrowser/visicalc/Cell.java   | 19 ++---
 .../bytezone/diskbrowser/visicalc/Choose.java |  6 --
 .../diskbrowser/visicalc/Condition.java       |  6 +-
 .../bytezone/diskbrowser/visicalc/Count.java  |  4 +-
 .../bytezone/diskbrowser/visicalc/Error.java  |  6 --
 .../diskbrowser/visicalc/Expression.java      | 11 +--
 .../bytezone/diskbrowser/visicalc/Format.java | 80 ++++++++++++-------
 src/com/bytezone/diskbrowser/visicalc/If.java |  4 +-
 .../bytezone/diskbrowser/visicalc/Int.java    |  3 +-
 .../diskbrowser/visicalc/IsError.java         |  4 +-
 .../bytezone/diskbrowser/visicalc/IsNa.java   |  3 +-
 .../bytezone/diskbrowser/visicalc/Lookup.java |  6 +-
 .../bytezone/diskbrowser/visicalc/Max.java    |  4 +-
 .../bytezone/diskbrowser/visicalc/Min.java    |  4 +-
 src/com/bytezone/diskbrowser/visicalc/Na.java |  6 --
 .../bytezone/diskbrowser/visicalc/Npv.java    |  4 +-
 .../bytezone/diskbrowser/visicalc/Number.java |  6 --
 src/com/bytezone/diskbrowser/visicalc/Or.java |  5 +-
 src/com/bytezone/diskbrowser/visicalc/Pi.java |  6 --
 .../bytezone/diskbrowser/visicalc/Sheet.java  |  2 +-
 .../bytezone/diskbrowser/visicalc/Sum.java    |  4 +-
 .../bytezone/diskbrowser/visicalc/Value.java  |  8 +-
 26 files changed, 111 insertions(+), 146 deletions(-)

diff --git a/src/com/bytezone/diskbrowser/visicalc/Abs.java b/src/com/bytezone/diskbrowser/visicalc/Abs.java
index afbcc0f..09239ad 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Abs.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Abs.java
@@ -10,7 +10,7 @@ public class Abs extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     if (source == null)
     {
@@ -20,7 +20,5 @@ public class Abs extends Function
 
     value = Math.abs (source.getValue ());
     valueType = source.getValueType ();
-
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/AbstractValue.java b/src/com/bytezone/diskbrowser/visicalc/AbstractValue.java
index 51fabdb..f5e0ae7 100644
--- a/src/com/bytezone/diskbrowser/visicalc/AbstractValue.java
+++ b/src/com/bytezone/diskbrowser/visicalc/AbstractValue.java
@@ -47,46 +47,51 @@ public abstract class AbstractValue implements Value
       case NA:
         return "NA";
       case ERROR:
-        return "Error";
+        return "ERROR";
       default:
         return "";
     }
   }
 
-  String getValueText (Value value, int depth)
+  @Override
+  public void calculate ()
+  {
+  }
+
+  // for debugging
+  String getValueText (int depth)
   {
     StringBuilder text = new StringBuilder ();
 
-    String typeText = "  " + value.getTypeText ();
-    if (value.isValueType (ValueType.VALUE))
+    String typeText = "  " + getTypeText ();
+    if (isValueType (ValueType.VALUE))
     {
-      String valueText = String.format ("%f", value.getValue ());
+      String valueText = String.format ("%f", getValue ());
       text.append (String.format ("| %-10s : %-69s |%n", typeText, valueText));
     }
     else
-      text.append (
-          String.format ("| %-10s : %-69s |%n", typeText, value.getValueType ()));
+      text.append (String.format ("| %-10s : %-69s |%n", typeText, getValueType ()));
 
-    if (value instanceof Expression)
+    if (this instanceof Expression)
     {
       text.append (
-          String.format ("| Expression : %-69s |%n", ((Expression) value).fullText ()));
-      for (Value v : (Expression) value)
-        text.append (getValueText (v, depth + 1));
+          String.format ("| Expression : %-69s |%n", ((Expression) this).fullText ()));
+      for (Value v : (Expression) this)
+        text.append (((AbstractValue) v).getValueText (depth + 1));
     }
-    else if (value instanceof Function)
+    else if (this instanceof Function)
     {
       text.append (
-          String.format ("| Function   : %-69s |%n", ((Function) value).fullText));
-      for (Value v : (Function) value)
-        text.append (getValueText (v, depth + 1));
+          String.format ("| Function   : %-69s |%n", ((Function) this).fullText));
+      for (Value v : (Function) this)
+        text.append (((AbstractValue) v).getValueText (depth + 1));
     }
-    else if (value instanceof Condition)
+    else if (this instanceof Condition)
     {
       text.append (
-          String.format ("| Condition  : %-69s |%n", ((Condition) value).fullText));
-      for (Value v : (Condition) value)
-        text.append (getValueText (v, depth + 1));
+          String.format ("| Condition  : %-69s |%n", ((Condition) this).fullText));
+      for (Value v : (Condition) this)
+        text.append (((AbstractValue) v).getValueText (depth + 1));
     }
 
     return text.toString ();
diff --git a/src/com/bytezone/diskbrowser/visicalc/And.java b/src/com/bytezone/diskbrowser/visicalc/And.java
index 9630b9d..ee0f738 100644
--- a/src/com/bytezone/diskbrowser/visicalc/And.java
+++ b/src/com/bytezone/diskbrowser/visicalc/And.java
@@ -16,7 +16,7 @@ class And extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     for (Condition condition : conditions)
     {
@@ -24,10 +24,9 @@ class And extends Function
       if (condition.getValue () == 0)
       {
         value = 0;
-        return this;
+        return;
       }
     }
     value = 1;
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Average.java b/src/com/bytezone/diskbrowser/visicalc/Average.java
index 9853708..a4693a3 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Average.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Average.java
@@ -11,7 +11,7 @@ public class Average extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     double total = 0.0;
     int totalChecked = 0;
@@ -39,7 +39,5 @@ public class Average extends Function
       value = total / totalChecked;
       valueType = ValueType.VALUE;
     }
-
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Cell.java b/src/com/bytezone/diskbrowser/visicalc/Cell.java
index 0679655..2fc47a9 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Cell.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Cell.java
@@ -2,7 +2,6 @@ package com.bytezone.diskbrowser.visicalc;
 
 class Cell extends AbstractValue implements Comparable<Cell>
 {
-  //  private static final DecimalFormat nf = new DecimalFormat ("#####0.00");
   private static final String line = "+----------------------------------------"
       + "--------------------------------------------+";
   private static final String empty = "                                        ";
@@ -10,7 +9,6 @@ class Cell extends AbstractValue implements Comparable<Cell>
   private final Address address;
   private final Sheet parent;
   private CellType cellType;
-  //  private final Format format = new Format ();
   private String expressionText;
   private char cellFormat = ' ';
 
@@ -72,6 +70,8 @@ class Cell extends AbstractValue implements Comparable<Cell>
 
   void setValue (String command)
   {
+    assert cellType == CellType.EMPTY;
+
     if (!command.isEmpty () && command.charAt (0) == '"')
     {
       label = command.substring (1);
@@ -143,10 +143,11 @@ class Cell extends AbstractValue implements Comparable<Cell>
         return Format.justify (empty, colWidth, ' ');
 
       case VALUE:
-        if (value == null)
-          calculate ();
+        if (!isValueType (ValueType.VALUE))
+          return Format.justify (value.getText (), colWidth, 'R');
+
         char formatChar = cellFormat != ' ' ? cellFormat : globalFormat;
-        return Format.format (value, formatChar, colWidth);
+        return " " + Format.format (value, formatChar, colWidth - 1);
 
       default:
         assert false;
@@ -193,10 +194,10 @@ class Cell extends AbstractValue implements Comparable<Cell>
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     if (value != null && value.isValueType (ValueType.VALUE))
-      return this;
+      return;
 
     if (value == null)
     {
@@ -208,7 +209,7 @@ class Cell extends AbstractValue implements Comparable<Cell>
 
     value.calculate ();
 
-    return this;
+    return;
   }
 
   public String getDebugText ()
@@ -240,7 +241,7 @@ class Cell extends AbstractValue implements Comparable<Cell>
         if (value == null)
           text.append (String.format ("| Value      : %-69s |%n", "null"));
         else
-          text.append (getValueText (value, 0));
+          text.append (((AbstractValue) value).getValueText (0));
         break;
 
       default:
diff --git a/src/com/bytezone/diskbrowser/visicalc/Choose.java b/src/com/bytezone/diskbrowser/visicalc/Choose.java
index 3609006..2f40660 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Choose.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Choose.java
@@ -17,10 +17,4 @@ public class Choose extends Function
     range = new Range (rangeText);
     source = new Number (sourceText);
   }
-
-  @Override
-  public Value calculate ()
-  {
-    return null;
-  }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Condition.java b/src/com/bytezone/diskbrowser/visicalc/Condition.java
index 995e4ab..780f487 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Condition.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Condition.java
@@ -49,7 +49,7 @@ class Condition extends AbstractValue implements Iterable<Value>
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     value = 0;
 
@@ -67,7 +67,7 @@ class Condition extends AbstractValue implements Iterable<Value>
 
     if (conditionExpression.isValueType (ValueType.ERROR)
         || valueExpression.isValueType (ValueType.ERROR))
-      return this;
+      return;
 
     double conditionResult = conditionExpression.getValue ();
     double valueResult = valueExpression.getValue ();
@@ -86,8 +86,6 @@ class Condition extends AbstractValue implements Iterable<Value>
       value = conditionResult >= valueResult ? 1 : 0;
     else
       System.out.printf ("Unexpected comparator result [%s]%n", comparator);
-
-    return this;
   }
 
   @Override
diff --git a/src/com/bytezone/diskbrowser/visicalc/Count.java b/src/com/bytezone/diskbrowser/visicalc/Count.java
index a34867b..d80d912 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Count.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Count.java
@@ -11,7 +11,7 @@ class Count extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     value = 0;
     valueType = ValueType.VALUE;
@@ -31,7 +31,5 @@ class Count extends Function
       if (cell.getValue () != 0.0)
         value++;
     }
-
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Error.java b/src/com/bytezone/diskbrowser/visicalc/Error.java
index f86e54a..07623e2 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Error.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Error.java
@@ -13,10 +13,4 @@ class Error extends Function
   {
     return 0;
   }
-
-  @Override
-  public Value calculate ()
-  {
-    return this;
-  }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Expression.java b/src/com/bytezone/diskbrowser/visicalc/Expression.java
index e3316bf..b335a19 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Expression.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Expression.java
@@ -29,7 +29,6 @@ class Expression extends AbstractValue implements Iterable<Value>
   // [.3*(B4+B7+B8+B9)]
   // [+N12+(P12*(.2*K12+K9-O12))]
 
-  //  private final List<Value> values = new ArrayList<Value> ();
   private final List<String> operators = new ArrayList<String> ();
   private final List<String> signs = new ArrayList<String> ();
 
@@ -144,12 +143,12 @@ class Expression extends AbstractValue implements Iterable<Value>
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     if (values.size () == 0)
     {
       System.out.println ("nothing to calculate: " + text);
-      return this;
+      return;
     }
 
     try
@@ -163,7 +162,7 @@ class Expression extends AbstractValue implements Iterable<Value>
       else
       {
         valueType = thisValue.getValueType ();
-        return this;
+        return;
       }
 
       String sign = signs.get (0);
@@ -181,7 +180,7 @@ class Expression extends AbstractValue implements Iterable<Value>
         else
         {
           valueType = thisValue.getValueType ();
-          return this;
+          return;
         }
 
         sign = signs.get (i);
@@ -211,8 +210,6 @@ class Expression extends AbstractValue implements Iterable<Value>
       valueType = ValueType.ERROR;
       e.printStackTrace ();
     }
-
-    return this;
   }
 
   private String checkBrackets (String input)
diff --git a/src/com/bytezone/diskbrowser/visicalc/Format.java b/src/com/bytezone/diskbrowser/visicalc/Format.java
index 26c4c41..10d2769 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Format.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Format.java
@@ -2,45 +2,63 @@ package com.bytezone.diskbrowser.visicalc;
 
 import java.text.DecimalFormat;
 
-import com.bytezone.diskbrowser.visicalc.Value.ValueType;
-
 public class Format
 {
   private static final DecimalFormat nf = new DecimalFormat ("#####0.00");
 
   static String format (Value value, char formatChar, int colWidth)
   {
-    if (!value.isValueType (ValueType.VALUE))
-      return justify (value.getText (), colWidth, formatChar);
+    double actualValue = value.getValue ();
+    if (actualValue == -0.0)
+      actualValue = 0;
 
-    if (formatChar == 'I')
+    switch (formatChar)
     {
-      String integerFormat = String.format ("%%%d.0f", colWidth);
-      return String.format (integerFormat, value.getValue ());
-    }
-    else if (formatChar == '$')
-    {
-      String currencyFormat = String.format ("%%%d.%ds", colWidth, colWidth);
-      return String.format (currencyFormat, nf.format (value.getValue ()));
-    }
-    else if (formatChar == '*')
-    {
-      String graphFormat = String.format ("%%-%d.%ds", colWidth, colWidth);
-      // this is not finished
-      return String.format (graphFormat, "********************");
-    }
-    else
-    {
-      // this could be improved
-      String numberFormat = String.format ("%%%d.5f", colWidth + 6);
-      String val = String.format (numberFormat, value.getValue ());
-      while (val.endsWith ("0"))
-        val = ' ' + val.substring (0, val.length () - 1);
-      if (val.endsWith ("."))
-        val = ' ' + val.substring (0, val.length () - 1);
-      if (val.length () > colWidth)
-        val = val.substring (val.length () - colWidth);
-      return val;
+      case 'L':
+      case 'R':
+      case ' ':
+        // this could be improved
+        String numberFormat = String.format ("%%%d.5f", colWidth + 6);
+        String val = String.format (numberFormat, actualValue);
+
+        while (val.endsWith ("0"))
+          val = val.substring (0, val.length () - 1);
+        if (val.endsWith ("."))
+          val = val.substring (0, val.length () - 1);
+        if (val.startsWith ("0."))
+          val = val.substring (1);
+
+        if (val.length () > colWidth)
+          val = val.substring (val.length () - colWidth);
+
+        //      System.out.printf ("len:%d fmt: %s%n", val.length (), formatChar);
+        if (val.startsWith (" ") && formatChar == 'L')
+        {
+          String leftFormat = String.format ("%%-%ds", colWidth);
+          val = String.format (leftFormat, val.trim ());
+        }
+
+        return val;
+
+      case 'I':
+        String integerFormat = String.format ("%%%d.0f", colWidth);
+        String result = String.format (integerFormat, actualValue);
+        if (result.length () > colWidth)
+          return ">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>".substring (0, colWidth);
+        return result;
+
+      case '$':
+        String currencyFormat = String.format ("%%%d.%ds", colWidth, colWidth);
+        return String.format (currencyFormat, nf.format (actualValue));
+
+      case '*':
+        String graphFormat = String.format ("%%-%d.%ds", colWidth, colWidth);
+        // this is not finished
+        return String.format (graphFormat, "********************");
+
+      default:
+        System.out.printf ("[%s]%n", formatChar);
+        return "??????????????????????".substring (0, colWidth);
     }
   }
 
diff --git a/src/com/bytezone/diskbrowser/visicalc/If.java b/src/com/bytezone/diskbrowser/visicalc/If.java
index 5c8ca59..e4c7965 100644
--- a/src/com/bytezone/diskbrowser/visicalc/If.java
+++ b/src/com/bytezone/diskbrowser/visicalc/If.java
@@ -24,7 +24,7 @@ class If extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     valueType = ValueType.VALUE;
     condition.calculate ();
@@ -59,8 +59,6 @@ class If extends Function
       else
         value = expFalse.getValue ();
     }
-
-    return this;
   }
 
   @Override
diff --git a/src/com/bytezone/diskbrowser/visicalc/Int.java b/src/com/bytezone/diskbrowser/visicalc/Int.java
index a9c3eba..30a504b 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Int.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Int.java
@@ -9,11 +9,10 @@ public class Int extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     Expression exp = new Expression (parent, functionText);
     value = (int) exp.getValue ();
     valueType = exp.getValueType ();
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/IsError.java b/src/com/bytezone/diskbrowser/visicalc/IsError.java
index 54c2bd8..f4520ed 100644
--- a/src/com/bytezone/diskbrowser/visicalc/IsError.java
+++ b/src/com/bytezone/diskbrowser/visicalc/IsError.java
@@ -10,14 +10,12 @@ class IsError extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     if (cell == null)
       cell = parent.getCell (functionText);
 
     value = cell == null ? 1 : cell.isValueType (ValueType.ERROR) ? 1 : 0;
     valueType = ValueType.VALUE;
-
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/IsNa.java b/src/com/bytezone/diskbrowser/visicalc/IsNa.java
index 4cc9044..0e87cc9 100644
--- a/src/com/bytezone/diskbrowser/visicalc/IsNa.java
+++ b/src/com/bytezone/diskbrowser/visicalc/IsNa.java
@@ -10,7 +10,7 @@ public class IsNa extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     if (expression == null)
       expression = new Expression (parent, functionText);
@@ -18,6 +18,5 @@ public class IsNa extends Function
     expression.calculate ();
     value = expression.getValue ();
     valueType = expression.getValueType ();
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Lookup.java b/src/com/bytezone/diskbrowser/visicalc/Lookup.java
index f15f5b5..5cbdfcd 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Lookup.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Lookup.java
@@ -18,7 +18,7 @@ class Lookup extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     if (source == null)
     {
@@ -30,7 +30,7 @@ class Lookup extends Function
     if (!source.isValueType (ValueType.VALUE))
     {
       valueType = source.getValueType ();
-      return this;
+      return;
     }
 
     double sourceValue = source.getValue ();
@@ -54,8 +54,6 @@ class Lookup extends Function
       value = adjacentCell.getValue ();
       valueType = ValueType.VALUE;
     }
-
-    return this;
   }
 
   // @LOOKUP(B8,F3...F16)
diff --git a/src/com/bytezone/diskbrowser/visicalc/Max.java b/src/com/bytezone/diskbrowser/visicalc/Max.java
index 18c5dde..a9afee6 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Max.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Max.java
@@ -11,7 +11,7 @@ class Max extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     value = Double.MIN_VALUE;
     int totalChecked = 0;
@@ -38,7 +38,5 @@ class Max extends Function
       valueType = ValueType.NA;
     else
       valueType = ValueType.VALUE;
-
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Min.java b/src/com/bytezone/diskbrowser/visicalc/Min.java
index 51ce4f1..d80c4ce 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Min.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Min.java
@@ -11,7 +11,7 @@ class Min extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     value = Double.MAX_VALUE;
     int totalChecked = 0;
@@ -38,7 +38,5 @@ class Min extends Function
       valueType = ValueType.NA;
     else
       valueType = ValueType.VALUE;
-
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Na.java b/src/com/bytezone/diskbrowser/visicalc/Na.java
index 02e4bb4..a01a737 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Na.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Na.java
@@ -13,10 +13,4 @@ public class Na extends Function
   {
     return 0;
   }
-
-  @Override
-  public Value calculate ()
-  {
-    return this;
-  }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Npv.java b/src/com/bytezone/diskbrowser/visicalc/Npv.java
index 8b9faca..83d706a 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Npv.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Npv.java
@@ -21,7 +21,7 @@ public class Npv extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     value = 0;
     valueType = ValueType.VALUE;
@@ -40,7 +40,5 @@ public class Npv extends Function
 
       double temp = cell.getValue ();
     }
-
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Number.java b/src/com/bytezone/diskbrowser/visicalc/Number.java
index e57115b..4defdb9 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Number.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Number.java
@@ -22,10 +22,4 @@ class Number extends AbstractValue
   {
     return String.format ("Number: %f", value);
   }
-
-  @Override
-  public Value calculate ()
-  {
-    return this;
-  }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Or.java b/src/com/bytezone/diskbrowser/visicalc/Or.java
index acc6fd2..a3029fd 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Or.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Or.java
@@ -16,7 +16,7 @@ class Or extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     for (Condition condition : conditions)
     {
@@ -24,10 +24,9 @@ class Or extends Function
       if (condition.getValue () == 1)
       {
         value = 1;
-        return this;
+        return;
       }
     }
     value = 0;
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Pi.java b/src/com/bytezone/diskbrowser/visicalc/Pi.java
index 2e9801e..66391e0 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Pi.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Pi.java
@@ -7,10 +7,4 @@ class Pi extends Function
     super (parent, text);
     value = Math.PI;
   }
-
-  @Override
-  public Value calculate ()
-  {
-    return this;
-  }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Sheet.java b/src/com/bytezone/diskbrowser/visicalc/Sheet.java
index 6439e5a..fd39181 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Sheet.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Sheet.java
@@ -21,7 +21,7 @@ public class Sheet
   private final Map<Integer, Cell> columnOrderCells = new TreeMap<Integer, Cell> ();
   private final List<String> lines = new ArrayList<String> ();
 
-  private char globalFormat;
+  private char globalFormat = ' ';
 
   private final Map<Integer, Integer> columnWidths = new TreeMap<Integer, Integer> ();
   private int columnWidth = 12;
diff --git a/src/com/bytezone/diskbrowser/visicalc/Sum.java b/src/com/bytezone/diskbrowser/visicalc/Sum.java
index 5a63890..ecac450 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Sum.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Sum.java
@@ -11,7 +11,7 @@ class Sum extends Function
   }
 
   @Override
-  public Value calculate ()
+  public void calculate ()
   {
     value = 0;
     valueType = ValueType.VALUE;
@@ -30,7 +30,5 @@ class Sum extends Function
 
       value += cell.getValue ();
     }
-
-    return this;
   }
 }
\ No newline at end of file
diff --git a/src/com/bytezone/diskbrowser/visicalc/Value.java b/src/com/bytezone/diskbrowser/visicalc/Value.java
index b260157..308d520 100644
--- a/src/com/bytezone/diskbrowser/visicalc/Value.java
+++ b/src/com/bytezone/diskbrowser/visicalc/Value.java
@@ -7,15 +7,15 @@ interface Value
     VALUE, ERROR, NA
   }
 
-  public double getValue ();
+  public double getValue ();          // if ValueType == VALUE
 
-  public String getText ();
+  public String getText ();           // if ValueType != VALUE
 
   public boolean isValueType (ValueType valueType);
 
   public ValueType getValueType ();
 
-  public Value calculate ();
+  public void calculate ();
 
-  public String getTypeText ();
+  public String getTypeText ();       // Number/Function/Expression etc
 }
\ No newline at end of file