Can someone answer for conversion in java? : Can someone guide me how to convert a string value(which is "15000000" to string "150.00"?

what I am trying is :

    public static String truncate(String str, int length) {
    		// Ensure String length is longer than requested size.
    		str = str.trim();
    		if (str.length() > length) {
    			str = str.substring(0, length - 1);
    		} 
    		    return str;
    		}
	    
private void populateDetails() throws BusinessObjectException, ParseException {
		List<PolicyProducerDetails> policyProducerDetailsList = null;; 

		if (results!=null) {
			policyProducerDetailsList = new ArrayList<PolicyProducerDetails>();
			for (Iterator<PolhierPprModel> iterator = results.iterator(); iterator.hasNext();) {
				PolhierPprModel resultPolhierPprModel = (PolhierPprModel) iterator.next();
{
					
	String test = resultPolhierPprModel.getCommRate().toString();
	 String test1 =truncate(test,4);
	 Float test2 = Float.parseFloat(test1);
	String test3 = String.valueOf(test2);
	policyProducerDetailsLocal.setCommRateOverride(test3);
}

Right now I am getting a 150.0 but I want to make it 150.00...Also I dont want it to be hardcoded as i have done.
Any Help will be great.