Static Keyword in Classes

Java's static Keyword: A Concise Guide for Spring Boot Developers

In Java, the static keyword designates a member (variable or method) as belonging to the class itself, not to any specific instance. This means:

1. Static Variables (Class Variables):

A single copy exists, shared across all instances.

public class MyClass {
    static int count = 0; // Shared counter

    public MyClass() {
        count++;
    }
}

2. Static Methods:

Called directly on the class, without needing an object. Useful for utility functions.

public class MathUtils {
    public static int add(int a, int b) {
        return a + b;
    }
}
//Usage: int sum = MathUtils.add(5,3);

3. Static Blocks:

Initialize static variables. Executed only once when the class is loaded.

public class MyStaticClass {
    static {
        System.out.println("Static block executed");
    }
}

Spring Boot Context:

In Spring Boot, @Component, @Service, @Repository etc. create singletons by default. Static members within these beans are shared across the entire application. Use cautiously to avoid unintended side-effects or race conditions (consider thread safety). Favor dependency injection for cleaner, more testable code. Static members are less amenable to testing and mocking.

Caution: Overuse of statics can hinder testability, maintainability, and lead to tightly coupled code. Use judiciously!