1. Introduction

In Java, it is a common practice to check if a string is empty or null before performing operations on it. This helps in avoiding NullPointerException and ensures the smooth execution of the program. This program demonstrates how to check if a string is empty or null using the == operator and the isEmpty method.

2. Program Steps

1. Define the main method which is the entry point to the program.

2. Declare and initialize two strings, one with a null value and another with an empty value.

3. Check if the strings are null or empty using the == operator and the isEmpty method and print the results.

3. Code Program

public class CheckString {
    public static void main(String[] args) {
        // Step 2: Declare and initialize two strings
        String nullString = null;
        String emptyString = "";

        // Step 3: Check if the strings are null or empty and print the results
        System.out.println("Checking with == operator and isEmpty method:");
        System.out.println("Is nullString null or empty? " + (nullString == null || nullString.isEmpty()));
        System.out.println("Is emptyString null or empty? " + (emptyString == null || emptyString.isEmpty()));
    }
}

Output:

Checking with == operator and isEmpty method:
Is nullString null or empty? true
Is emptyString null or empty? true

4. Step By Step Explanation

– Step 1: The main method is defined as the entry point to the program.

– Step 2: Two strings, nullString and emptyString, are declared and initialized with null and empty values respectively.

– Step 3: The program checks if nullString and emptyString are either null or empty using the == operator and the isEmpty method. The result is printed, indicating that both strings are either null or empty.

This program illustrates the importance of handling null and empty strings in Java to prevent potential issues in the code execution.