Java String formatted() Method

The String.formatted() method in Java is used to create a formatted string using the specified arguments. This method is part of the String class and was introduced in Java 15. It provides a convenient way to format strings similarly to the String.format() method but in a more fluent and readable manner.

Table of Contents

1. Introduction
2. formatted Method Syntax
3. Examples
   • Basic Usage
   • Using Different Data Types
   • Handling Edge Cases
   • Real-World Use Case
4. Conclusion

Introduction

The String.formatted() method is a member of the String class in Java. It allows you to format a string by replacing placeholders with specified arguments. This method is useful for creating readable and maintainable formatted strings.

formatted() Method Syntax

The syntax for the formatted method is as follows:

public String formatted(Object... args)

• args: The arguments to be formatted into the string.

Examples

Basic Usage

The formatted method can be used to replace placeholders in a string with the specified arguments.

Example

public class FormattedExample {
    public static void main(String[] args) {
        String template = "Hello, %s!";
        String result = template.formatted("World");
        System.out.println(result);
    }
}

Output:

Hello, World!

Using Different Data Types

The formatted method can handle various data types, such as integers, floating-point numbers, and objects.

Example

public class FormattedDataTypesExample {
    public static void main(String[] args) {
        String template = "Name: %s, Age: %d, Score: %.2f";
        String result = template.formatted("John", 25, 85.75);
        System.out.println(result);
    }
}

Output:

Name: John, Age: 25, Score: 85.75

Handling Edge Cases

Example: Missing Arguments

If the number of arguments provided is less than the number of placeholders, an IllegalFormatException will be thrown.

public class FormattedMissingArgumentsExample {
    public static void main(String[] args) {
        try {
            String template = "Hello, %s! You are %d years old.";
            String result = template.formatted("John");
            System.out.println(result);
        } catch (IllegalFormatException e) {
            System.out.println("Error: " + e.getMessage());
        }
    }
}

Output:

Error: Format specifier '%d'

Example: Extra Arguments

If the number of arguments provided is more than the number of placeholders, the extra arguments are ignored.

public class FormattedExtraArgumentsExample {
    public static void main(String[] args) {
        String template = "Hello, %s!";
        String result = template.formatted("John", 25);
        System.out.println(result);
    }
}

Output:

Hello, John!

Real-World Use Case

Example: Formatting User Information

One common use case for formatted is to format user information for display or logging.

public class FormatUserInfoExample {
    public static void main(String[] args) {
        String template = "User: %s, Email: %s, Age: %d";
        String userInfo = template.formatted("Alice", "alice@example.com", 30);
        System.out.println(userInfo);
    }
}

Output:

User: Alice, Email: alice@example.com, Age: 30

In this example, the formatted method is used to format user information into a readable string.

Conclusion

The String.formatted() method in Java is a powerful and convenient tool for creating formatted strings using specified arguments. It provides a more fluent and readable alternative to String.format(). By understanding and utilizing the formatted method, you can efficiently manage string formatting tasks in your Java programs, making your code more readable and maintainable.