How to increment the value from textfield in java

I want to fetch the values from a textfield and then increment it by one. My problem is that the value which I will fetch also contain some text at beginig for eg: SBI20132012000 I need to fetch the last 3 digits and want to increment it by 1.

    package myproj.util;
    
    import java.text.SimpleDateFormat;
    import java.util.Date;
    import myproj.DATAENTRY;
    
    
    public class CalendarUtil {
      
        private static String lastUsedDatePrefix = "";
        public static int counter = 0;
    
        public String getRemId() {
            final String datePrefix = new SimpleDateFormat("yyyyMMdd").format(new Date());
            if (lastUsedDatePrefix.equals(datePrefix)) {
                DATAENTRY dt = new DATAENTRY();
                String text = dt.tf_rm_id.getText().substring(8);// get the value from textfield and increment it
                int text1=Integer.parseInt(text);
                counter=text1;
                CalendarUtil.counter++;
            } else {
               CalendarUtil.lastUsedDatePrefix = datePrefix;
               CalendarUtil.counter = 1;
            }
            final String counterSuffix = ((100 <= CalendarUtil.counter) ? "" : (10 <= CalendarUtil.counter) ? "0" : "00") + CalendarUtil.counter;
            return datePrefix + counterSuffix;
        }
        
    }