Individual components of an array are referenced by the array name and by an integer which represents their position in the array. The numbers you use to identify them are called subscripts or indexes into the array.
Subscripts are consecutive integers beginning with 0. Thus the
array k
above has components k[0]
,
k[1]
, and k[2]
. Since you start counting at
zero there is no k[3]
, and trying to access it will
throw an ArrayIndexOutOfBoundsException
. You can use
array components wherever you'd use a similarly typed variable that
wasn't part of an array. For example this is how you'd store values
in the arrays above:
k[0] = 2;
k[1] = 5;
k[2] = -2;
yt[17] = 7.5f;
names[4] = "Fred";
This step is called initializing the array or, more precisely, initializing the components of the array. Sometimes the phrase "initializing the array" is used to mean when you initialize all the components of the array.
For even medium sized arrays, it's unwieldy to specify each component individually. It is often helpful to use for loops to initialize the array. Here is a loop which fills an array with the squares of the numbers from 0 to 100.
float[] squares;
squares = new float[101];
for (int i=0; i <= 100; i++) {
squares[i] = i*i;
}
Two things you should note about this code fragment: