Write a program that replaces all tab characters '\t' in a file with the appropriate number of spaces. By default, the distance between tab columns should be 3 (the value we use in this book for Java programs) but it can be changed by the user. Expand tabs to the number of spaces necessary to move to the next tab column. That may be less than three spaces. For example, consider the line containing "\t|\t||\t|". The first tab is changed to three spaces, the second to two spaces, and the third to one space. Your program should be executed as

java TabExpander filename


java TabExpander -t tabwidth filename

Complete the following file: