Method to Insert Commas into Large Numbers

java, number-formatting

Solution

With `NumberFormat` you can do this easily:

NumberFormat format = NumberFormat.getInstance(Locale.US);

System.out.println(format.format(100));
System.out.println(format.format(1000));
System.out.println(format.format(1000000));

will ouput:

100
1,000
1,000,000

Problem

Is there a method that already exists and if not can a method be written that can format large numbers and insert commas into them? ``` 100 = 100 1000 = 1,000 10000 = 10,000 100000 = 100,000 1000000 = 1,000,000 public String insertCommas(Integer largeNumber) { } ```

Original source