ARR - Traversing Arrays (Lesson)

Traversing Arrays

Introduction

Working with large amounts of data makes programs more useful and interesting. Lots of data opens lots of opportunities! However, how do you deal with all that data? The more information that we use the more painstaking the process to get through it all. How can we manage big data but still break it down to individual elements when necessary?

Enter our amazing loops! With for and while loops we can stop off to visit each value of an array but still work with the entire set of data. Read on to learn how…

Looping through an Array

Click below to begin the Looping through an Array activity.

Try It.png Read through the Sound Free Response Question from the 2011 AP CS exam:

For this free response question your job is to write the limitAmplitude method. Here are some hints to get you started:

Create a counter to keep track of the numbers of amplitude changes.
Write a loop that traverse samples.
Within the loop check to see if each samples element is less than -limit
- if it is, change that element of the array to -limit and increase the counter
Within the loop check to see if each samples element is greater than limit
- if it is, change that element of the array to limit and increase the counter
Return the counter

Here is one possible way to write this method:

ArrayIndexOutOfBoundsException (Error)

When working with arrays it is not uncommon to get an out of bounds error. This means that your code was reaching outside the bounds (or index) of your array.

For example:

double score [ ] = new double [ 5 ];
score [2] = 23.2;
score [3] = 20.1;
score [5] = 22.3; / / Error! There is no index 5!