Question: Explain the concept of scope and lifetime of variables in programming. Provide an example in Java to illustrate the concept.

Answer: Scope and lifetime of variables are important concepts in programming. The scope of a variable refers to the region of the program in which the variable is accessible, while the lifetime of a variable refers to the period during which the variable exists in memory.

In Java, variables have different scopes and lifetimes based on where they are declared. There are primarily three types of scopes: block, method, and class. The lifetime of a variable depends on its scope and may vary from short to long.

public class ScopeAndLifetimeExample {
    int instanceVariable; // Instance variable with class scope

    public void exampleMethod() {
        int methodVariable = 10; // Method variable with method scope

        if (condition) {
            int blockVariable = 20; // Block variable with block scope
            System.out.println(blockVariable); // blockVariable is accessible here
        }
        System.out.println(methodVariable); // methodVariable is accessible here
        System.out.println(instanceVariable); // instanceVariable is accessible here
    }

    public static void main(String[] args) {
        ScopeAndLifetimeExample example = new ScopeAndLifetimeExample();
        example.exampleMethod();
       //instanceVariable and methodVariable are not accessible here
    }
}

In the example above, we have an instanceVariable with class scope and lifetime, a methodVariable with method scope, and a blockVariable with block scope. The instanceVariable is accessible throughout the class, the methodVariable is accessible within the exampleMethod, and the blockVariable is only accessible within the if block.

The instanceVariable exists as long as the object of the class exists, the methodVariable exists as long as the method is being executed, and the blockVariable exists as long as the block of code in which it is declared is being executed.

Understanding the scope and lifetime of variables is crucial for writing efficient and error-free programs. It helps prevent naming conflicts, optimize memory usage, and ensure data integrity.