Creating a trimmed method

I am having a very hard time with one of my projects. See below

Write a program that consists of three classes. The first class will be the actual program.

The second class will simply convert a string to lower case.

The third class will have three methods:

public static String trimmed(String str)

public static String trimmed(String str, int len)

public static String squeeze(String str)

The 1st trimmed method will return str without leading or trailing whitespace and will return an empty string if str is null.

The 2nd trimmed method will return the first len characters after trimming the string. The 2nd method must make use of the 1st method.

The squeeze method will replace all sequences of 2 spaces with 1 space.

The program will read a file containing the data below (cut and paste it into notepad and save it), and will display each line:

  1. as entered but trimmed and squeezed.
  2. as entered but trimmed, squeezed, and shortened to 10 characters
  3. as entered but trimmed, squeezed, converted to lower case, and shortened to 20 characters.

Data (copy after this line down to (not including) the line that says end data, you will have 5 lines):

 This is a test, this is only a test!

This test is a test of your Java programming skills!
end data