Practicing with File I/O

Introduction

The goal of this lab is to practice working with Java file I/O by adding load/save functionality to the Document class you completed in a previous lab.

Since we will be working with a command-line Java application, you should not use Eclipse for this lab. You can edit the Java files using the gedit text editor and compile your code in the terminal. The Web-CAT submission tests for this lab won't run Checkstyle, so you don't need to worry about low-level formatting issues.

As a reminder, you can follow the following steps to compile and execute a Java program in the terminal:

$ cd the_directory_where_your_code_is_stored
$ javac File1.java File2.java ...
$ java File1

This example assumes that File1.java contains the main method for the application.

Resources

Useful API documents:

• java.util.Scanner
• java.io.File
• java.io.PrintWriter

Files

The following unfinished files are provided:

• Document.java
• Editor.java This is an editor application that provides a command-line interface to the Document class.

Instructions - Part 1

Download the files above and complete Document.java so that the unfinished methods conform to the Javadoc comments. Test your completed file by running the provided application program.

Instructions - Part 2

The current implementation of the Editor class does not include code for handling exceptions related to file I/O: If you attempt to open a non-existent file, or to write a file to a location where do not have permission, the application will crash.

Modify Editor.java by removing all throws declarations and adding try/catch blocks to saveFile and loadFile. If an exception occurs, these methods should print a helpful error message and then allow execution to proceed normally.

Instructions - Part 3 (If Time)

Most text editors allow you to save the current document without re-entering the file name. Modify the Editor class so that it provides this functionality. If the file is already associated with a file name (because of an earlier save or load) then the "s" command should now save the current version without prompting for a file name. You should also add a save-as command to allow specifying a file name even if one already exists. Use "w" to trigger save-as. Make sure to update the help message to conform to the new functionality.

Submitting

Submit your completed version of Document.java through Web-CAT. Style checking is turned off, and you have an unlimited number of submissions. If you have trouble with your submission, you may find it helpful to look at the JUnit submission tests: DocumentTestWithIO.java.