CSIS 110 โ Lecture 35
Chapter 8 - Arrays
Reading: 8.1 to 8.2.3 (pages 381 โ 389)
8.4 to 8.6 (pages 396 โ 417)
Arrays and Methods
Last time we looked at passing arrays to methods. Let's say that I have a method named
doIt - how would I declare a formal parameter that is an array of int?
We looked at methods that
- calculated the sum of the elements of an array
- printed the elements of an array
- returned the minimum value contained in an array
- returned the index of the array element that contains the smallest value
- Searched for a value in an array, and returned the index of the first element that
contained that value.
Array size
Before continuing with arrays and methods, let's revisit the array size.
When you allocate the array, its size is fixed - you can't make it smaller or larger.
However, you can reassign the array reference to a different array.
Look at ArrayAssign.java.
Note that I have changed the reference, and that the elements of a1 are not longer
referenced - garbage collected.
Now let's look at ArrayAssign2.java - the assignment statement does not copy the values
of the array - it only changes the reference. So when I modify a2[2], it appears to modify
a1[2] also, because both a1 and a2 are references to the same array.
Assigning values to array elements in methods
So far, these methods have only accessed the elements of the arrays, but they have not
made any assignments to the arrays or the array elements. Let's look at another method.
Look at ArrayZero.java.
What's going on? Draw pictures. Emphasize that arrays are reference types.
Let's look at another example: ArrayCopy.java.
