Code that creates a phone number

StringBuilder phoneNumber = new StringBuilder();
phoneNumber.append("977");
phoneNumber.append("555");
phoneNumber.append("1212");
Code that adds dashes to a phone number
phoneNumber.insert(3, '-');
phoneNumber.insert(7, '-');

Code that removes dashes from a phone number

for(int i = 0; i < phoneNumber.length(); i++)
{
    if (phoneNumber.charAt(i) == '-')
        phoneNumber.deleteCharAt(i--);
}

Code that parses a phone number

StringBuilder phoneNumber = new StringBuilder("977-555-1212");
String areaCode = phoneNumber.substring(0,3);
String prefix = phoneNumber.substring(4,7);
String suffix = phoneNumber.substring(8);

Code that shows how capacity automatically increases

StringBuilder name = new StringBuilder(8);
int capacity1 = name.capacity();       // capacity1 is 8
name.append("Raymond R. Thomas");
int length = name.length();            // length is 17
int capacity2 = name.capacity();    // capacity2 is 18 (2 * capacity1 + 2)