What Does Static Mean?

The term static refers to a keyword in programming languages that can be assigned to variables, methods, and classes. When a variable, method, or class is designated as static, it indicates that it stands apart from the instantiation of an object. In simpler terms, the value of a static variable, the functionality of a static method, and the attributes of a static class remain constant across all instances of that class.

Explaining Static to a Child

Imagine you have a toy that features a button that triggers a specific action, such as making a sound or lighting up. This button represents a method in programming.

In programming, we sometimes have methods or variables that should be uniform across all instances we create. Instead of each toy having its own button, we want them all to share one. That's the essence of static in programming.

For instance, consider a toy car that should always have four wheels. By using a static variable, we can ensure that every toy car has four wheels, regardless of how many are produced. This allows the program to manage consistency without us having to remember each detail.

In summary, static is a unique keyword in programming that ensures certain attributes remain the same for all objects we generate.

Static Variables

A static variable is a variable that is universally shared among all instances of a class. When declared as static, it resides in the class memory rather than in the stack or heap. Consequently, all instances share the same static variable value. This variable is initialized just once, and its value is retained across all instances of the class.

Static variables are particularly useful for keeping track of information shared among instances. For example, if we were designing a class to represent bank accounts, we could utilize a static variable to count the total number of accounts created.

Static Methods

A static method belongs to a class rather than any specific instance of that class. This characteristic allows you to invoke a static method without needing to instantiate the class. To declare a static method, simply prefix the method name with the static keyword.

Static methods are advantageous when performing tasks that do not rely on the state of an object. For example, if creating a class for mathematical operations, a static method could be employed to compute the value of a function without requiring an instance of the class.

Static Classes

A static class cannot be instantiated and may only contain static members, such as static variables and methods. This type of class is typically utilized to group related static methods together.

Static classes are beneficial when you want to organize related methods without needing to create an instance of the class. A prime example is the static class Math in the .NET Framework, which encompasses various mathematical functions like sine, cosine, and tangent.

Examples of Static in Java

Static Variables

public class BankAccount {

private static int totalAccounts = 0;

private int accountNumber;

public BankAccount() {

totalAccounts++;

accountNumber = totalAccounts;

}

public static int getTotalAccounts() {

return totalAccounts;

}

}

In this illustration, totalAccounts serves as a static variable shared by all instances of the BankAccount class. It tracks the total number of accounts created, while the getTotalAccounts method is also static and returns this value.

Static Methods

public class MathFunctions {

public static double squareRoot(double x) {

return Math.sqrt(x);

}

public static double power(double base, double exponent) {

return Math.pow(base, exponent);

}

}

Here, squareRoot and power are both static methods in the MathFunctions class. They can be called without creating an instance and perform mathematical operations, returning results.

Static Classes

public class StringUtils {

private StringUtils() {}

public static boolean isNullOrEmpty(String str) {

return str == null || str.isEmpty();

}

}

In this example, StringUtils is a static class that cannot be instantiated and contains only static methods, like isNullOrEmpty, which checks if a string is null or empty. This class groups related string manipulation methods.