Java array FAQ: Can you show some Java array examples, specifically some Java String array examples, as well as the Java 5 for loop syntax?

Sure. In this tutorial, we demonstrate how to declare, populate, and iterate through a Java String array, including many String array source code examples, including the Java 5 for loop syntax.

Declaring a Java String array with an initial size

You can declare a Java String array and give it an initial size like this:

public class JavaStringArrayTests
{
  private String[] toppings = new String[20];
  // more to the class here ...
}

In that example, we create a Java String array named toppings, where the toppings array has been given an initial size of 20 elements.

Later on, in a Java method in your class, you can populate the elements in the String array like this:

void populateStringArray()
{
  toppings[0] = "Cheese";
  toppings[1] = "Pepperoni";
  toppings[2] = "Black Olives";
  // ...
}

As you can see, a Java array (in this case a String array) begins with an element numbered zero (they are zero-based), just like the C programming language.

Declare a Java String array with no initial size

You can also declare a Java String array without giving it an initial size, like this:

public class JavaStringArrayTests
{
  private String[] toppings;
  // more to the class here ...
}

Then later on in your code you can give your Java array a size, and populate it as desired, like this:

void populateStringArray()
{
  toppings = new String[20];
  toppings[0] = "Cheese";
  toppings[1] = "Pepperoni";
  toppings[2] = "Black Olives";
  // ...
}

This approach is very similar to the previous approach, but as you can see, we don't give the String array a size until the populateStringArray method is called. (If you'd like to know all the differences, just leave a comment below, and I'll be glad to provide more details.)

Declaring and populating a Java String array

You don't have to declare a Java String array in two steps, you can do everything in one step, like this:

public class JavaStringArrayTests
{
  private String[] toppings = {"Cheese", "Pepperoni", "Black Olives"};
}

This example is similar to our previous example, with the following differences:

1. The toppings array is defined and populated in one step.
2. This toppings array has only three elements in it.

Iterating through a Java String array - Before Java 5

Before Java 5, the way to loop through a String array involved getting the number of elements in the array, and then looping through the array with a for loop. Here's a complete source code example that demonstrates the syntax prior to Java 5:

public class JavaStringArrayTests1
{
  private String[] toppings = {"Cheese", "Pepperoni", "Black Olives"};

  // our constructor; print out the String array here
  public JavaStringArrayTests1()
  {
    int size = toppings.length;
    for (int i=0; i<size; i++)
    {
      System.out.println(toppings[i]);
    }
  }

  // main kicks everything off.
  // create a new instance of our class here.
  public static void main(String[] args)
  {
    new JavaStringArrayTests1();
  }
}

Iterating through a Java String array - After Java 5

With the advent of Java 5, we can make our for loops a little cleaner and easier to read, so looping through a Java String array is even easier. Here's a complete source code example that demonstrates the Java 5 syntax:

public class JavaStringArrayTests2
{
  private String[] toppings = {"Cheese", "Pepperoni", "Black Olives"};

  // our constructor; print out the String array here
  public JavaStringArrayTests2()
  {
    for (String s: toppings)
    {
      System.out.println(s);
    }
  }

  // main kicks everything off.
  // create a new instance of our class here.
  public static void main(String[] args)
  {
    new JavaStringArrayTests2();
  }
}

I think you'll agree that the Java 5 syntax for looping through a Java String array is more concise, and easier to read.

Java String array - what's related

As I wrap up my collection of "Java String array" tutorials, here are a few links to my current String array in Java tutorials:

• How to create an array in Java
• Java String array - find the longest String in an array
• How to sort a Java String array
• How to create a String array in Java