DecimalFormat: Fix memory leak

DecimalFormat keeps a list of FieldPosition attributes for use
by formatToCharacterIterator(). However, all format() methods add
attributes to this list, even if they are not needed. Also, the
list is only cleared by formatToCharacterIterator() (which might
not be called at all).

Fix this by only recording attribute information when required,
and clearing the list immediately after use.

Fixes #28 (BZ#30977)

Author: phvega

java/text/DecimalFormat.java

@@ -313,20 +313,30 @@ public int hashCode()
    * @return The String representation of this long.
    */
   public final StringBuffer format(Object obj, StringBuffer sbuf, FieldPosition pos)
+  {
+    return format(obj, sbuf, pos, false);
+  }
+
+  private StringBuffer format(Object obj, StringBuffer sbuf, FieldPosition pos,
+                              boolean addAttrs)
   {
     if (obj instanceof BigInteger)
       {
         BigDecimal decimal = new BigDecimal((BigInteger) obj);
-        formatInternal(decimal, true, sbuf, pos);
+        formatInternal(decimal, true, sbuf, pos, addAttrs);
         return sbuf;
       }
     else if (obj instanceof BigDecimal)
       {
-        formatInternal((BigDecimal) obj, true, sbuf, pos);
+        formatInternal((BigDecimal) obj, false, sbuf, pos, addAttrs);
         return sbuf;
       }
+    else if (obj instanceof Number)
+      {
+        return format(((Number) obj).doubleValue(), sbuf, pos, addAttrs);
+      }
 
-    return super.format(obj, sbuf, pos);
+    throw new IllegalArgumentException("Cannot format given Object as a Number");
   }
 
   /**
@@ -341,6 +351,12 @@ else if (obj instanceof BigDecimal)
    */
   public StringBuffer format(double number, StringBuffer dest,
                              FieldPosition fieldPos)
+  {
+    return format(number, dest, fieldPos, false);
+  }
+
+  private StringBuffer format(double number, StringBuffer dest,
+                              FieldPosition fieldPos, boolean addAttrs)
   {
     // special cases for double: NaN and negative or positive infinity
     if (Double.isNaN(number))
@@ -384,7 +400,7 @@ else if (Double.isInfinite(number))
       {
         // get the number as a BigDecimal
         BigDecimal bigDecimal = new BigDecimal(String.valueOf(number));
-        formatInternal(bigDecimal, false, dest, fieldPos);
+        formatInternal(bigDecimal, false, dest, fieldPos, addAttrs);
       }
 
     return dest;
@@ -401,9 +417,15 @@ else if (Double.isInfinite(number))
    */
   public StringBuffer format(long number, StringBuffer dest,
                              FieldPosition fieldPos)
+  {
+    return format(number, dest, fieldPos, false);
+  }
+
+  private StringBuffer format(long number, StringBuffer dest,
+                              FieldPosition fieldPos, boolean addAttrs)
   {
     BigDecimal bigDecimal = new BigDecimal(String.valueOf(number));
-    formatInternal(bigDecimal, true, dest, fieldPos);
+    formatInternal(bigDecimal, true, dest, fieldPos, addAttrs);
     return dest;
   }
 
@@ -430,9 +452,7 @@ public AttributedCharacterIterator formatToCharacterIterator(Object value)
       IllegalArgumentException("Cannot format given Object as a Number");
 
     StringBuffer text = new StringBuffer();
-    attributes.clear();
-    super.format(value, text, new FieldPosition(0));
-
+    format(value, text, new FieldPosition(0), true);
     AttributedString as = new AttributedString(text.toString());
 
     // add NumberFormat field attributes to the AttributedString
@@ -444,6 +464,7 @@ public AttributedCharacterIterator formatToCharacterIterator(Object value)
         as.addAttribute(attribute, attribute, pos.getBeginIndex(),
                         pos.getEndIndex());
       }
+    attributes.clear();
 
     // return the CharacterIterator from AttributedString
     return as.getIterator();
@@ -1764,9 +1785,10 @@ else if (ch == patternSeparator)
    * @param isLong A boolean that indicates if this BigDecimal is a real
    * decimal or an integer.
    * @param fieldPos Use to keep track of the formatting position.
+   * @param addAttrs If true, attribute information will be recorded.
    */
   private void formatInternal(BigDecimal number, boolean isLong,
-                              StringBuffer dest, FieldPosition fieldPos)
+                              StringBuffer dest, FieldPosition fieldPos, boolean addAttrs)
   {
     // The specs says that fieldPos should not be null, and that we
     // should throw a NPE, but it seems that in few classes that
@@ -1798,7 +1820,8 @@ private void formatInternal(BigDecimal number, boolean isLong,
 
         _multiplier = negativePatternMultiplier;
 
-        addAttribute(Field.SIGN, attributeStart, dest.length());
+        if (addAttrs)
+          addAttribute(Field.SIGN, attributeStart, dest.length());
       }
     else
       {
@@ -1930,7 +1953,8 @@ private void formatInternal(BigDecimal number, boolean isLong,
       }
 
     // add the INTEGER attribute
-    addAttribute(Field.INTEGER, attributeStart, dest.length());
+    if (addAttrs)
+      addAttribute(Field.INTEGER, attributeStart, dest.length());
 
     // ...update field position, if needed, and return...
     if ((fieldPos.getField() == INTEGER_FIELD ||
@@ -1940,7 +1964,7 @@ private void formatInternal(BigDecimal number, boolean isLong,
         fieldPos.setEndIndex(endIndexInt);
       }
 
-    handleFractionalPart(dest, fractPart, fieldPos, isLong);
+    handleFractionalPart(dest, fractPart, fieldPos, isLong, addAttrs);
 
     // and the exponent
     if (this.useExponentialNotation)
@@ -1949,15 +1973,17 @@ private void formatInternal(BigDecimal number, boolean isLong,
 
         dest.append(symbols.getExponential());
 
-        addAttribute(Field.EXPONENT_SYMBOL, attributeStart, dest.length());
+        if (addAttrs)
+          addAttribute(Field.EXPONENT_SYMBOL, attributeStart, dest.length());
         attributeStart = dest.length();
 
         if (exponent < 0)
           {
             dest.append(symbols.getMinusSign());
             exponent = -exponent;
 
-            addAttribute(Field.EXPONENT_SIGN, attributeStart, dest.length());
+            if (addAttrs)
+              addAttribute(Field.EXPONENT_SIGN, attributeStart, dest.length());
           }
 
         attributeStart = dest.length();
@@ -1971,7 +1997,8 @@ private void formatInternal(BigDecimal number, boolean isLong,
         for (int i = 0; i < exponentLength; ++i)
           dest.append(exponentString.charAt(i));
 
-        addAttribute(Field.EXPONENT, attributeStart, dest.length());
+        if (addAttrs)
+          addAttribute(Field.EXPONENT, attributeStart, dest.length());
       }
 
     // now include the suffixes...
@@ -1993,9 +2020,10 @@ private void formatInternal(BigDecimal number, boolean isLong,
    * @param fractPart
    * @param fieldPos
    * @param isLong
+   * @param addAttrs
    */
   private void handleFractionalPart(StringBuffer dest, String fractPart,
-                                    FieldPosition fieldPos, boolean isLong)
+                                    FieldPosition fieldPos, boolean isLong, boolean addAttrs)
   {
     int dotStart = 0;
     int dotEnd = 0;
@@ -2071,10 +2099,10 @@ else if (!this.decimalSeparatorAlwaysShown)
           }
       }
 
-    if (addDecimal)
+    if (addAttrs && addDecimal)
       addAttribute(Field.DECIMAL_SEPARATOR, dotStart, dotEnd);
 
-    if (addFractional)
+    if (addAttrs && addFractional)
       addAttribute(Field.FRACTION, fractStart, fractEnd);
 
     if ((fieldPos.getField() == FRACTION_FIELD ||