Check out setParseBigDecimal in DecimalFormat. With this setter, parse will return a BigDecimal for you.

Your parsing method will throw that exception if str is an empty string ("") or a space (" "). You may need to do some extra checking, e.g.,

if (str == null || str.trim().length() == 0) {
    normalized = "0";

The BigDecimal(double) constructor can have unpredictable behaviors. It is preferable to use BigDecimal(String) or BigDecimal.valueOf(double).

System.out.println(new BigDecimal(135.69)); //135.68999999999999772626324556767940521240234375
System.out.println(new BigDecimal("135.69")); // 135.69
System.out.println(new BigDecimal("13۵.۶9")); // 135.69
System.out.println(BigDecimal.valueOf(135.69)); // 135.69

The documentation for BigDecimal(double) explains in detail:

1. The results of this constructor can be somewhat unpredictable. One might assume that writing new BigDecimal(0.1) in Java creates a BigDecimal which is exactly equal to 0.1 (an unscaled value of 1, with a scale of 1), but it is actually equal to 0.1000000000000000055511151231257827021181583404541015625. This is because 0.1 cannot be represented exactly as a double (or, for that matter, as a binary fraction of any finite length). Thus, the value that is being passed in to the constructor is not exactly equal to 0.1, appearances notwithstanding.
2. The String constructor, on the other hand, is perfectly predictable: writing new BigDecimal("0.1") creates a BigDecimal which is exactly equal to 0.1, as one would expect. Therefore, it is generally recommended that the String constructor be used in preference to this one.
3. When a double must be used as a source for a BigDecimal, note that this constructor provides an exact conversion; it does not give the same result as converting the double to a String using the Double.toString(double) method and then using the BigDecimal(String) constructor. To get that result, use the static valueOf(double) method.

Try this

// Create a DecimalFormat that fits your requirements
DecimalFormatSymbols symbols = new DecimalFormatSymbols();
symbols.setGroupingSeparator(',');
symbols.setDecimalSeparator('.');
String pattern = "#,##0.0#";
DecimalFormat decimalFormat = new DecimalFormat(pattern, symbols);
decimalFormat.setParseBigDecimal(true);

// parse the string
BigDecimal bigDecimal = (BigDecimal) decimalFormat.parse("10,692,467,440,017.120");
System.out.println(bigDecimal);

If you are building an application with I18N support you should use DecimalFormatSymbols(Locale)

Also keep in mind that decimalFormat.parse can throw a ParseException so you need to handle it (with try/catch) or throw it and let another part of your program handle it

You can use BigDecimal#toString to convert a BigDecimal to string

It's quite possible that caseXObj is null, so it'll cause the NullPointerException. You should test the three cases like this:

caseX caseXObj = caseXBo.getCaseXDao().findCaseXBySID(selectedID);
if (caseXObj != null && caseXObj.getCaseInGrossAmt() != null) {
    // do something with caseXObj 
} else if (caseXObj == null) {
    // initialize caseXObj, you were misssing this case!
} else {
    caseXObj.setCaseAmt(BigDecimal.ZERO);
}

In essence, the error was that you were testing for only two cases - and there are three of them.

BigDecimal.ZERO is a predefined constant and therefore doesn't have to be evaluated from a string at runtime as BigDecimal("0") would be. It will be faster and won't require creation of a new object.

If your code needs to run on pre-1.5, then you can use the (much maligned) Singleton pattern to create an object equivalent to BigDecimal.ZERO. The first time it is used, it would call BigDecimal("0") to create a zero object, and return that object on subsequent calls. Otherwise, if your code is running on a 1.5 system, your singleton object can just return BigDecimal.ZERO with no runtime penalty.

You could use

BigDecimal number = new BigDecimal("1234567") .movePointLeft(2):

Don't use doubles as suggested because you would certainly lose precision and with BigDecimal you won't. It's important when working with currencies.