Top 10 Best Practices for Java Strings (Updated for Java 21 LTS)

Strings are everywhere in Java. Whether you're processing text, formatting output, or handling user input, using Strings efficiently improves performance, reduces memory waste, and makes code cleaner.

With Java 21, we get new enhancements like StringTemplate, making string handling even more powerful. Let’s explore 10 best practices for working with Strings in Java while leveraging the latest features.

1️⃣ Use StringTemplate Instead of + for String Formatting (Java 21)

Why?

Concatenating strings using + works, but it's messy and error-prone. Java 21 introduces StringTemplate, making string formatting safer and more readable.

✅ Best Practice: Use StringTemplate.STR for cleaner formatting.

🔹 Example: Using StringTemplate the Right Way

import static java.lang.StringTemplate.STR;

public class StringTemplateExample {
    public static void main(String[] args) {
        String name = "Amit";
        int age = 30;

        // ✅ Java 21 String Template (Cleaner & Safer)
        String message = STR."Hello, my name is \{name} and I am \{age} years old.";
        System.out.println(message);
    }
}

💡 Use StringTemplate instead of + or String.format() for better readability.

Notes on StringTemplate:

• Supports embedded expressions (\{}) directly inside the template.
• Avoids manual string concatenation mistakes.
• Improves code readability and maintainability.

2️⃣ Use .isEmpty() Instead of length() == 0 for Checking Empty Strings

Why?

Using length() == 0 works, but .isEmpty() is more readable and intent-expressive.

✅ Best Practice: Use .isEmpty() to check for empty strings.

🔹 Example: Cleaner Empty Check

String str = "";

if (str.isEmpty()) {
    System.out.println("String is empty");
}

💡 For Java 11+, use .isBlank() to check if a string is empty or contains only spaces.

3️⃣ Use repeat() Instead of Loops for Repeating Strings (Java 11+)

Why?

Instead of looping to repeat strings manually, use .repeat() for cleaner and faster repetition.

✅ Best Practice: Use .repeat() when generating repeated patterns.

🔹 Example: Generating a Pattern

public class RepeatExample {
    public static void main(String[] args) {
        System.out.println("*".repeat(5)); // Output: *****
    }
}

💡 Perfect for UI formatting, logging, and text-based designs.

4️⃣ Use .strip() Instead of .trim() for Whitespace Handling (Java 11+)

Why?

trim() only removes ASCII spaces, while strip() removes all Unicode whitespace characters, making it better for global applications.

✅ Best Practice: Use .strip() instead of .trim().

🔹 Example: Proper Whitespace Removal

String input = "  Java  ";

System.out.println(input.strip());        // ✅ Removes spaces correctly
System.out.println(input.stripLeading()); // ✅ Removes leading spaces
System.out.println(input.stripTrailing());// ✅ Removes trailing spaces

💡 Always use .strip() when working with user input.

5️⃣ Prefer String.join() Over Manual Concatenation

Why?

Instead of manually appending values using +, use String.join() for better readability and efficiency.

✅ Best Practice: Use String.join() for structured string concatenation.

🔹 Example: Cleaner String Joining

import java.util.List;

public class StringJoinExample {
    public static void main(String[] args) {
        List<String> names = List.of("Java", "Python", "C++");

        // ✅ Efficient and clean
        String result = String.join(", ", names);
        System.out.println(result); // Output: Java, Python, C++
    }
}

💡 Great for CSV file generation and logging.

6️⃣ Use translateEscapes() to Process Escape Sequences (Java 15+)

Why?

Handling escape sequences manually can be tricky. .translateEscapes() automatically converts them.

✅ Best Practice: Use .translateEscapes() for handling text with escape sequences.

🔹 Example: Properly Handling Escape Sequences

public class TranslateEscapesExample {
    public static void main(String[] args) {
        String text = "Hello\\nJava"; // Escape sequence inside string
        System.out.println(text.translateEscapes()); // ✅ Converts \n to a newline
    }
}

💡 Use this when processing text from configuration files or APIs.

7️⃣ Use .formatted() Instead of String.format() (Java 15+)

Why?

.formatted() is cleaner and more readable than String.format().

✅ Best Practice: Use .formatted() when formatting strings dynamically.

🔹 Example: Using .formatted() for Better Readability

public class FormattedExample {
    public static void main(String[] args) {
        String name = "Amit";
        int age = 30;

        String message = "Hello, my name is %s and I am %d years old.".formatted(name, age);
        System.out.println(message);
    }
}

💡 More concise than String.format().

8️⃣ Use .indent() for Better String Formatting (Java 12+)

Why?

Manually adding spaces for indentation is error-prone. .indent() simplifies it.

✅ Best Practice: Use .indent() for multi-line string formatting.

🔹 Example: Using .indent() for Readability

public class IndentExample {
    public static void main(String[] args) {
        String text = "Java\nis\nawesome";
        System.out.println(text.indent(4)); // ✅ Adds 4 spaces to each line
    }
}

💡 Useful for formatted console output, logs, and reports.

9️⃣ Use Files.readString() Instead of BufferedReader for Small Files (Java 11+)

✅ Best Practice: Use Files.readString() for reading small files.

🔹 Example: Simplifying File Reading

import java.nio.file.Files;
import java.nio.file.Path;
import java.io.IOException;

public class FileReadExample {
    public static void main(String[] args) throws IOException {
        Path filePath = Path.of("example.txt");
        String content = Files.readString(filePath);
        System.out.println(content);
    }
}

💡 For large files, prefer BufferedReader to avoid memory issues.

🔟 Use .matches() for Quick Regex Checks Instead of Pattern.compile()

✅ Best Practice: Use .matches() for quick regex validation.

🔹 Example: Checking an Email Format

public class RegexExample {
    public static void main(String[] args) {
        String email = "test@example.com";

        if (email.matches("[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}")) {
            System.out.println("Valid email");
        }
    }
}

💡 Simpler than manually compiling regex patterns.

🚀 Summary: 10 Best Practices for Java Strings (Java 21)

✅ Use StringTemplate for cleaner formatting.
✅ Use .isEmpty() instead of length() == 0.
✅ Use .repeat() instead of loops for repetition.
✅ Use .strip() instead of .trim().
✅ Use String.join() for structured concatenation.
✅ Use .translateEscapes() for escape sequence handling.
✅ Use .formatted() instead of String.format().
✅ Use .indent() for structured output formatting.
✅ Use Files.readString() for simple file reading.
✅ Use .matches() for quick regex validation.