Question

I’m extracting value from XML and trying to convert it to an appropriate Object… Lets say, value can be numeric/boolean/String.
as an example…

<value> 123 </value>
<value> TRUE </value>
<value> some Strings </value>

I’m reading the value from XML as String. Any idea what would be the best approach to convert the String to the appropriate java Object? (ie. BigDecimal/Boolean/String)
This is what I’m thinking as a solution:

    private Object convertParameterValIntoObject(String value){

    Object toreturn = null;
    BigDecimal numeric = null;
    Boolean boo = null;

    try{        
        //deal with numeric val
        numeric = new BigDecimal(value.trim());
        return numeric;         
    }
    catch (NumberFormatException e) {

        try{
            //deal with Boolean
            if(value.trim().equalsIgnoreCase("true") || 
                    value.trim().equalsIgnoreCase("false")){

                boo = new Boolean(value.trim());
                return boo;
            }
            else throw new Exception();
        }
        catch (Exception e1) {

            // String 
            return value.trim();
        }
    }       
}

Thanks in advance,
Hasan.

Answer 1

You could use java.util.Scanner which has all the type detection you need. Here’s a working example. You need to make sure you probe the type from the most specific to the least specific, here I test for boolean, then number, then string.

String[] testValues = { "123", "123.4", "FALSE", "false",
        "some strings" };

for (String test : testValues) {
    Scanner scanner = new Scanner(test);
    scanner.useDelimiter("^");
    if (scanner.hasNextBoolean()) {
        boolean value = scanner.nextBoolean();
        System.out.println("boolean " + value);
    } else if (scanner.hasNextDouble()) {
        double value = scanner.nextDouble();
        System.out.println("number " + value);
    } else if (scanner.hasNext(".*")) {
        String value = scanner.next();
        System.out.println("string " + value);
    }
}

Output

number 123.0
number 123.4
boolean false
boolean false
string some strings