CS 1054 Introduction to Programming in Java (Spring 2008)

Lab 10: File I/O - Text files.

Lab Objectives

• Learn how to read a text file using the Scanner class
• Learn how to write a file using the PrintWriter class

Instructions

1. There will be no webcat submission for this week's lab. The TA has to look through your code.
2. Begin by downloading Lab10.zip, save the file, and then extract it in a folder you can locate. Open this project in BlueJ. Make sure TextFileReader, TextFileWriter, and URLReader are compiled.
3. Study TextFileReader, execute it, and make sense of how it reads a file. Locate the Test.txt file in the directory of the BlueJ project. Open it using a text editor such as Notepad and modify its contents. Save it and run TextFileReader again to verify that the output changes.
4. Try to display TextFileReader.java. Remember that the programs you write are also text files!
5. Next, study TextFileWriter, execute it, and make sense of how it reads from keyboard input and write what you input to a file. Locate the Output.txt in the directory and verify that the input was saved correctly. Experiment with saving input to a different file.
6. The next step is to complete the TextFileCopy class. It has to read the contents of a text file line by line and save them to a different file. In order to complete it you must use portions of the other two classes given. Make sure you create two files, a Scanner and a PrintWriter. Once you are done show your code to the TA and demonstrate that it works.
7. Finally look at the URLReader class. It outputs the HTML code for a given website URL. Make sure you are using unlimited buffering as some codes can be very long. To verify that the output is correct you can open the webpage in a Firefox then press +U to display the HTML. Try outputting different webpages.