Simple Example on JLex:
Calculate the Number of Words, Characters, and Lines in a File

This simple example uses JLex -- the Java-version of unix "lex" utility for generation of scanners.

In this example, we calculate the numbers of words, characters, and lines in the given file. Of course, you need JLex to be installed on your computer (see JLex manual).

To compile from the JLex-source (file CalcWord.l), perform the command 

    make
It firstly calls JLex, that creates the "CalcWord.l.java" file: 
    java JLex.Main CalcWord.l
Then (in case of no errors) it compiles the resulting Java-file: 
    javac CalcWord.l.java
It creates Yylex.class and some other classes.

To run the resulting program, perform the command 

    java Yylex filename
where "filename" is a name of input file.