# Declare and Initialize Arrays in Java with Examples

> Declare and initialize one-dimensional, two-dimensional, and multidimensional arrays in Java with examples for both immediate and dynamic value assignment

**URL:** https://sentry.io/answers/how-do-i-declare-and-initialize-an-array-in-java/

---

## The Problem

How do I declare and initialize an array in Java?

## The Solution

The easiest way to declare and initialize an array of a primitive type such as `int` in Java is by using the following syntax.

```java
int[] myArray = new int[]{1, 2, 3};
```

This does a few things at once.

* The `int[] myArray` says that we want to declare a new variable called `myArray` that has the type of an array of integers.
* `new int[]` says we want to immediately allocate memory to store data in this array.
* `{1,2,3}` is the data we want to store in the array. Java will count the elements in our initial array and automatically initialize the array with enough memory for three `int`s.

Here's a runnable example:

```java
class Main {

    public static void main(String[] args) {

        // declare the variable and allocate memory
        int[] myArray = new int[]{1, 2, 3};
        for (int i = 0; i < 3; i++) {
            System.out.println(myArray[i]);
        }
    }
}
```

Which will print out:

```
1
2
3
```

If you don't want to hard code the data immediately when you initialize the array, you can instead create an empty array (with all values initialized to zero) as follows.

```java
int[] myArray = new int[3];
```

Here, you have to explicitly give the size of the array. In our example, we've created an array that can store 3 `int`s, all of which are zero.

Here's a runnable example of dynamically setting the values in an array.

```java
class Main {

    public static void main(String[] args) {

        // declare the variable and allocate memory
        int[] myArray = new int[3];
        myArray[1] = 100;
        for (int i = 0; i < 3; i++) {
            System.out.println(myArray[i]);
        }
    }
}
```

Which will print:

```
0
100
0
```

### Other Types of Arrays

You can use the same syntax to create arrays to store other objects. In the example below, we use `Integer` instead of `int`, which is very similar to the above code but initializes the default values to `null` instead of `0`.

```java
class Main {

    public static void main(String[] args) {

        // declare the variable and allocate memory
        Integer[] myArray = new Integer[3];
        myArray[1] = 100;
        for (int i = 0; i < 3; i++) {
            System.out.println(myArray[i]);
        }
    }
}
```

The code prints:

```
null
100
null
```

## Initialize a two-dimensional (2D) array in Java

You can create a 2D array in Java by adding a second set of square brackets, for example:

```java
int[][] myArray = new int[4][2];
```

This will create an array with four rows and two columns. Here's a runnable example:

```java
class Main {

    public static void main(String[] args) {

        // declare the variable and allocate memory
        int[][] myArray = new int[4][2];
        myArray[2][1] = 1;
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 2; j++) {
                System.out.print(myArray[i][j] + " ");
            }
            System.out.println();
        }
    }
}
```

This prints the following (we set the value of the third row and second column to 1, and the rest of the values all have the default 0).

```
0 0
0 0
0 1
0 0
```

## Initialize a Multidimensional Array in Java

You can initialize more dimensions by adding more square brackets, for example:

```java
int[][][] myArray = new int[4][2][3];
```

Arrays with three or more dimensions are harder to visualize, but here's a runnable example that prints it out as four sets of 2-by-3 arrays.

```java
class Main {

    public static void main(String[] args) {

        // declare the variable and allocate memory
        int[][][] myArray = new int[4][2][3];
        myArray[2][1][2] = 1;
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 2; j++) {
                for (int k = 0; k < 3; k++) {
                    System.out.print(myArray[i][j][k] + " ");
                }
                System.out.println();
            }
            System.out.println("____");
        }
    }
}
```

This will print:

```
0 0 0
0 0 0
____
0 0 0
0 0 0
____
0 0 0
0 0 1
____
0 0 0
0 0 0
____
```

---

*Source: [sentry.io/answers/how-do-i-declare-and-initialize-an-array-in-java/](https://sentry.io/answers/how-do-i-declare-and-initialize-an-array-in-java/)*