Program: 39983
Project: 39983
Buggy source:
protected ArrayList<Token> tokenize(String expression) throws ParsingException {
  ArrayList<Token> tokens=new ArrayList<>();
  String number="String_Node_Str";
  TokenType last=TokenType.LEFTPAR;
  int pars=0;
  for (  char c : (expression + ' ').toCharArray()) {
    if (Character.isDigit(c) || c == '.') {
      if (last == TokenType.NUMBER) {
        throw new ParsingException("String_Node_Str");
      }
      number+=c;
    }
 else     if (c == '+' || c == '-' || c == '*' || c == '/') {
      if (!number.isEmpty()) {
        tokens.add(new Token(TokenType.NUMBER,number));
        last=TokenType.NUMBER;
        number="String_Node_Str";
      }
      if (last == TokenType.LEFTPAR || last == TokenType.UNARY_OP || last == TokenType.BINARY_OP) {
        if (c != '+' && c != '-') {
          throw new ParsingException("String_Node_Str" + c);
        }
        tokens.add(new Token(TokenType.UNARY_OP,"String_Node_Str" + c));
        last=TokenType.UNARY_OP;
      }
 else {
        tokens.add(new Token(TokenType.BINARY_OP,"String_Node_Str" + c));
        last=TokenType.BINARY_OP;
      }
    }
 else     if (Character.isWhitespace(c)) {
      if (!number.isEmpty()) {
        tokens.add(new Token(TokenType.NUMBER,number));
        last=TokenType.NUMBER;
        number="String_Node_Str";
      }
    }
 else     if (c == '(') {
      if (!number.isEmpty() || last == TokenType.NUMBER || last == TokenType.RIGHTPAR) {
        throw new ParsingException("String_Node_Str");
      }
      tokens.add(new Token(TokenType.LEFTPAR,"String_Node_Str"));
      last=TokenType.LEFTPAR;
      pars++;
    }
 else     if (c == ')') {
      if (!number.isEmpty()) {
        tokens.add(new Token(TokenType.NUMBER,number));
        last=TokenType.NUMBER;
        number="String_Node_Str";
      }
      if (last == TokenType.LEFTPAR || last == TokenType.BINARY_OP || last == TokenType.UNARY_OP) {
        throw new ParsingException("String_Node_Str");
      }
      if (pars <= 0) {
        throw new ParsingException("String_Node_Str");
      }
      tokens.add(new Token(TokenType.RIGHTPAR,"String_Node_Str"));
      last=TokenType.RIGHTPAR;
      pars--;
    }
 else {
      throw new ParsingException("String_Node_Str" + c);
    }
  }
  if (pars != 0) {
    throw new ParsingException("String_Node_Str");
  }
  return tokens;
}

Fixed version (ground truth):
/** 
 * Converts the expression into a list of tokens.
 * @param expression the expression to convert
 * @return list of tokens
 * @throws ParsingException if the expression could not be tokenized
 */
protected ArrayList<Token> tokenize(String expression) throws ParsingException {
  ArrayList<Token> tokens=new ArrayList<>();
  String number="String_Node_Str";
  TokenType last=TokenType.LEFTPAR;
  int pars=0;
  for (  char c : (expression + ' ').toCharArray()) {
    if (Character.isDigit(c) || c == '.') {
      if (last == TokenType.NUMBER) {
        throw new ParsingException("String_Node_Str");
      }
      number+=c;
    }
 else     if (c == '+' || c == '-' || c == '*' || c == '/') {
      if (!number.isEmpty()) {
        tokens.add(new Token(TokenType.NUMBER,number));
        last=TokenType.NUMBER;
        number="String_Node_Str";
      }
      if (last == TokenType.LEFTPAR || last == TokenType.BINARY_OP) {
        if (c != '+' && c != '-') {
          throw new ParsingException("String_Node_Str" + c);
        }
        tokens.add(new Token(TokenType.UNARY_OP,"String_Node_Str" + c));
        last=TokenType.UNARY_OP;
      }
 else       if (last == TokenType.UNARY_OP) {
        throw new ParsingException("String_Node_Str");
      }
 else {
        tokens.add(new Token(TokenType.BINARY_OP,"String_Node_Str" + c));
        last=TokenType.BINARY_OP;
      }
    }
 else     if (Character.isWhitespace(c)) {
      if (!number.isEmpty()) {
        tokens.add(new Token(TokenType.NUMBER,number));
        last=TokenType.NUMBER;
        number="String_Node_Str";
      }
    }
 else     if (c == '(') {
      if (!number.isEmpty() || last == TokenType.NUMBER || last == TokenType.RIGHTPAR) {
        throw new ParsingException("String_Node_Str");
      }
      tokens.add(new Token(TokenType.LEFTPAR,"String_Node_Str"));
      last=TokenType.LEFTPAR;
      pars++;
    }
 else     if (c == ')') {
      if (!number.isEmpty()) {
        tokens.add(new Token(TokenType.NUMBER,number));
        last=TokenType.NUMBER;
        number="String_Node_Str";
      }
      if (last == TokenType.LEFTPAR || last == TokenType.BINARY_OP || last == TokenType.UNARY_OP) {
        throw new ParsingException("String_Node_Str");
      }
      if (pars <= 0) {
        throw new ParsingException("String_Node_Str");
      }
      tokens.add(new Token(TokenType.RIGHTPAR,"String_Node_Str"));
      last=TokenType.RIGHTPAR;
      pars--;
    }
 else {
      throw new ParsingException("String_Node_Str" + c);
    }
  }
  if (pars != 0) {
    throw new ParsingException("String_Node_Str");
  }
  return tokens;
}