🔧 Top 25 Utility Functions Every Java Project Needs — Part 1

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🧾 Introduction

Whether you’re working on a small utility tool or a massive enterprise application, certain utility functions are always helpful. They save time, reduce repetition, and improve code quality.

In this two-part guide, we’ll cover 25 essential utility functions — written using modern Java features like Optional, Pattern Matching, records, and Java 21 enhancements. In Part 1, we'll explore the first 10.

1. isNullOrBlank(String input)

Checks whether a string is null or blank (empty or whitespace only).

✅ Java Implementation:

public static boolean isNullOrBlank(String input) {
    return input == null || input.isBlank();
}

🔄 Usage:

if (isNullOrBlank(user.getName())) {
    throw new IllegalArgumentException("Name cannot be blank");
}

2. capitalize(String input)

Converts the first letter to uppercase and leaves the rest unchanged.

✅ Java Implementation:

public static String capitalize(String input) {
    if (isNullOrBlank(input))…