Code quality fix - Exception classes should be immutable.

src/main/java/us/monoid/json/JSONException.java

@@ -10,14 +10,15 @@ public class JSONException extends Exception {
 	 * 
 	 */
 	private static final long serialVersionUID = 0;
-	private Throwable cause;
+	private final Throwable cause;
 
     /**
      * Constructs a JSONException with an explanatory message.
      * @param message Detail about the reason for the exception.
      */
     public JSONException(String message) {
         super(message);
+        cause = null;
     }
 
     public JSONException(Throwable t) {

src/main/java/us/monoid/web/jp/javacc/ParseException.java

@@ -49,11 +49,17 @@ public ParseException(Token currentTokenVal,
 
   public ParseException() {
     super();
+    currentToken = null;
+    expectedTokenSequences = null;
+    tokenImage = null;
   }
 
   /** Constructor with message. */
   public ParseException(String message) {
     super(message);
+    currentToken = null;
+    expectedTokenSequences = null;
+    tokenImage = null;
   }
 
 
@@ -62,21 +68,21 @@ public ParseException(String message) {
    * this object has been created due to a parse error, the token
    * followng this token will (therefore) be the first error token.
    */
-  public Token currentToken;
+  public final Token currentToken;
 
   /**
    * Each entry in this array is an array of integers.  Each array
    * of integers represents a sequence of tokens (by their ordinal
    * values) that is expected at this point of the parse.
    */
-  public int[][] expectedTokenSequences;
+  public final int[][] expectedTokenSequences;
 
   /**
    * This is a reference to the "tokenImage" array of the generated
    * parser within which the parse error occurred.  This array is
    * defined in the generated ...Constants interface.
    */
-  public String[] tokenImage;
+  public final String[] tokenImage;
 
   /**
    * It uses "currentToken" and "expectedTokenSequences" to generate a parse
@@ -131,7 +137,7 @@ private static String initialise(Token currentToken,
   /**
    * The end of line string for this machine.
    */
-  protected String eol = System.getProperty("line.separator", "\n");
+  protected final String eol = System.getProperty("line.separator", "\n");
 
   /**
    * Used to convert raw characters to their escaped version

src/main/java/us/monoid/web/jp/javacc/TokenMgrError.java

@@ -41,7 +41,7 @@ public class TokenMgrError extends Error
    * Indicates the reason why the exception is thrown. It will have
    * one of the above 4 values.
    */
-  int errorCode;
+  final int errorCode;
 
   /**
    * Replaces unprintable characters by their escaped (or unicode escaped)
@@ -131,6 +131,7 @@ public String getMessage() {
 
   /** No arg constructor. */
   public TokenMgrError() {
+      errorCode = 0;
   }
 
   /** Constructor with message and reason. */