Arrays in Java

Arrays in Java work very similar to the “original” arrays we know from system-near programming languages like C and C++. Therefore, arrays are fixed in size and the size must be defined during declaration.

Declaring and Initializing an array

Only declaring array in Java is possible in two ways. Both syntaxes are legitimate.

String people[] = new String[3];
String[] people = new String[3];

The examples create empty arrays with the size of 3. Instead, we can also assign the values directly:

String people[] = { "Max", "Anna", "Tom" };

As Java can infer the number of elements, we don’t need to provide a size.

A value from an array can be returned with the syntax we know from most programming languages

String[] people = { "Anna", "Max" };
System.out.println(people[0]); // Anna
System.out.println(people[1]); // Max

Setting and overwriting array values

String people[] = new String[3];
people[0] = "John";
people[1] = "Tom";
people[2] = "Anna";

Looping over arrays

With a for-loop:

String people[] = { "Max", "Anna", "Tom" };
for (int i = 0; i < people.length; i++) {
  System.out.println(people[i]);
}

Or, with a for-each:

String people[] = { "Max", "Anna", "Tom" };
for (String person : people) {
  System.out.println(person);
}

Java array methods

Here is an overview, of the most important methods