A Java int array example

 

Java array FAQ: How do you create an array of Java int values (i.e., a Java “int array”)?

Answer: There are several ways to define an int array in Java; let’s take a look at a few examples.

1) Declare a Java int array with initial size; populate it later

If you know the desired size of your array, an you'll be adding elements to your array some time later in your code, you can define a Java int array using this syntax:

 

// (1) create a java int array
int[] intArray = new int[3];
 
// (2) some time later ... assign elements to the array
intArray[0] = 1;
intArray[1] = 2;
intArray[2] = 3;
 
// (3) print our java int array
for (int i=0; i<intArray.length; i++)
{
  System.out.println(intArray[i]);
}

　　

2) Declare an int array and populate its elements

Depending on your needs, you can also create your int array using this syntax:

 

// (1) define your java int array
int[] intArray = new int[] {4,5,6,7,8};
 
// (2) print the java int array
for (int i=0; i<intArray.length; i++)
{
  System.out.println(intArray[i]);
}

　　

3) A complete Java int array example

Sometimes it helps to see source code used in a complete Java program, so the Java class/program below demonstrates the different Java int array examples.

The method named intArrayExample shows our first example. Then, to demonstrate the similiarity between an int array and a String array, the method named stringArrayExample shows how a Java Stringarray is typically created and populated. Finally, the method named intArrayExample2 shows our secondint array example (as shown above).

Here's the source code for my sample Java class:

 

/**
 * Demonstrates several Java array examples, including a
 * Java int array, and a Java String array.
 * Created by Alvin Alexander, <a href="http://alvinalexander.com" title="http://alvinalexander.com">http://alvinalexander.com</a>.
 */
public class JavaIntArrayExample
{
 
  public static void main(String[] args)
  {
    new JavaArrayExample();
  }
 
  public JavaArrayExample()
  {
    intArrayExample();
    stringArrayExample();
    intArrayExample2();
  }
 
  /**
   * Create an int array, then populate the array, 
   * and finally print each element in the int array.
   */
  private void intArrayExample()
  {
    int[] intArray = new int[3];
    intArray[0] = 1;
    intArray[1] = 2;
    intArray[2] = 3;
    System.out.println("intArray output");
    for (int i=0; i<intArray.length; i++)
    {
      System.out.println(intArray[i]);
    }
  }
 
  /**
   * Create a String array, then populate the array, 
   * and finally print each element in the int array.
   */
  private void stringArrayExample()
  {
    String[] stringArray = new String[3];
    stringArray[0] = "a";
    stringArray[1] = "b";
    stringArray[2] = "c";
    System.out.println("stringArray output");
    for (int i=0; i<stringArray.length; i++)
    {
      System.out.println(stringArray[i]);
    }
  }
 
  /**
   * Create a Java int array and populate it in one step.
   * Then get the array length and print each element in the array.
   */
  private void intArrayExample2()
  {
    int[] intArray = new int[] {4,5,6,7,8};
    System.out.println("intArray output (version 2)");
    for (int i=0; i<intArray.length; i++)
    {
      System.out.println(intArray[i]);
    }
  }
 
}