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CS 206 Introduction to Computer Science II 09 / 14 / 2009 Instructor: Michael Eckmann.

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Presentation on theme: "CS 206 Introduction to Computer Science II 09 / 14 / 2009 Instructor: Michael Eckmann."— Presentation transcript:

1 CS 206 Introduction to Computer Science II 09 / 14 / 2009 Instructor: Michael Eckmann

2 Michael Eckmann - Skidmore College - CS 206 - Fall 2009 Today’s Topics More Java Review –Exception Handling –FileIO –StringTokenizer

3 Michael Eckmann - Skidmore College - CS 206 - Fall 2009 Java “review” Exception handling, try/catch blocks (import java.util.*;)‏ File I/O (import java.io.*;)‏ StringTokenizer

4 Michael Eckmann - Skidmore College - CS 206 - Fall 2009 Exception handling Exception handling allows for a program to detect unwanted behaviour and then instead of crashing the program, “catch” the exception while the program is running and handle it by doing something to allow the program to keep running. Let's see an example with catching an exception from Integer.parseInt

5 Michael Eckmann - Skidmore College - CS 206 - Fall 2009 Exception handling Some methods “throw” exceptions that are required to be caught, while others like Integer.parseInt don't require catching the exception. When we write our own methods, we can throw exceptions back to the caller. For example, if we have a method that takes in one int parameter, if the value passed in is required to be >=0, then the first code we write inside the method could be to check if negative and if so, throw an exception.

6 Michael Eckmann - Skidmore College - CS 206 - Fall 2009 File I/O File Input and Output Reading, Writing, Appending There are many classes in Java to handle reading and writing to files. We're going to focus on a few that allow reading and writing to “text files” (human readable) as opposed to “binary files.” Also, we're only going to focus on files that are “sequential” as opposed to “random access.”

7 Michael Eckmann - Skidmore College - CS 206 - Fall 2009 File I/O For file Input I recommend using a BufferedReader wrapped around a FileReader For file Output I recommend using a PrintWriter wrapped around a FileOutputStream Let's look at example code.

8 Michael Eckmann - Skidmore College - CS 206 - Fall 2009 StringTokenizer StringTokenizer is a class that allows us to easily “divide” up a String into tokens which are separated by a delimiter character. Let's look at some example code.

9 Michael Eckmann - Skidmore College - CS 206 - Fall 2009 Programming Examples Let's write a simple insertion sort method to sort the Cards in the ArrayList. To remind ourselves of how insertion sort works, let's look at: http://math.hws.edu/TMCM/java/xSortLab/


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