array.length
The length of an array — the number of elements. A field, not a method: no parentheses.
Available since: Java 1.0
Syntax
public final int lengthExamples
The length and the last element:
void main() {
int[] numbers = {4, 8, 15, 16, 23, 42};
IO.println(numbers.length);
IO.println(numbers[numbers.length - 1]);
}Output:
6
42A loop over indexes, and going out of bounds:
void main() {
String[] names = new String[3];
names[0] = "Anna";
for (int i = 0; i < names.length; i++) {
IO.println(i + ": " + names[i]);
}
try {
names[3] = "Oleg";
} catch (ArrayIndexOutOfBoundsException e) {
IO.println(e.getMessage());
}
}Output:
0: Anna
1: null
2: null
Index 3 out of bounds for length 3Notes
The size of an array is fixed when it is created. New arrays are filled with default values: 0 for numbers, false for boolean, null for objects. Indexes go from 0 to length - 1. If you need a list that grows, use ArrayList.
Do not mix them up: arrays have length, strings length(), collections size().
See also
- Arrays.toString() — Returns the contents of an array as a string like [1, 2, 3].
- for — A loop with a counter, or iteration over every element of an array or collection (for-each).
- String.length() — Returns the number of characters in a string.
In the tutorial
- Arrays — Arrays in Java: creating them, index access, length, default values, looping over them and printing with Arrays.toString.