Array
Use this to find the length of an array
a.length
Use this to find the length of a string
a.length()
when an array is passed as a parameter, it is possible to
alter the contents of the array
Sequence of values of the same type
array
Accessing a nonexistent element in an array results in
bounds error
How to grow an array that has ran out of space
create a new larger array, copy all elements into the array, store the reference to the new array in the array variable. double[] newData = new double[2*data.length]; System.arraycopy(data,0, newData, 0, data.length); data=newData;
Traversing an array with a regular for loop
double data[ ] = ...; for(int i=0; i<data.length; i++)
Declaration of an array variable
double[ ] data= new double[10];
Array length is
fixed (if you decide you need to add additional elements, then you need to make a new array)
The ArrayList class is a ______ class
generic; ArrayList<T> collects objects of type T
form a tabular, two dimensional arrangement with an index pair a[i][j]
two-dimensional arrays
How do you access array elements?
with an integer index using the notation a[ i ]
When you construct an ArrayList object, it has a size of?
0
How do you create an array of 5 ints? int[] arr = new int[6]; int[] arr = new int[5]; int arr = new int[5]; int arr = new int;
int[] arr = new int[5];
To set an array list element to a new value, use the
set method; For example, accounts.set(2, anAccount); sets position two of the accounts array list to anAccount, overwriting whatever value was there before
Sequence of values of the same type
Array
Example of array list
ArrayList<BankAccount> accounts = new ArrayList<BankAccount>(); accounts.add(new BankAccount(1001)); // The type ArrayList<BankAccount> denotes an array list of bank accounts. The angle brackets around BankAccount tell you that this is a type parameter//
You can collect a sequence of floating-point numbers in
ArrayList<Double>
Array
Arrays are ordered lists
If you know all the elements that you want to place in the array, you can create it by
int[ ] primes = {2, 3, 5, 7, 11}; (The Java compiler counts how many elements you want to place in an array, allocates an array of the correct size, and fills it with the elements that you specify)
