Java String trim() Method

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The String.trim() method in Java is used to remove leading and trailing whitespace from a string. This guide will cover the method's usage, explain how it works, and provide examples to demonstrate its functionality.

Table of Contents

1. Introduction
2. trim Method Syntax
3. Examples
   • Removing Leading and Trailing Whitespace
   • Handling Strings Without Leading or Trailing Whitespace
   • Comparison Before and After Trimming
4. Conclusion

Introduction

The String.trim() method is a member of the String class in Java. It allows you to remove leading and trailing whitespace from a string, which is particularly useful for cleaning up user input, formatting data, and ensuring consistent string comparisons.

trim Method Syntax

The syntax for the trim method is as follows:

public String trim()

Examples

Removing Leading and Trailing Whitespace

The trim method can be used to remove leading and trailing whitespace from a string.

Example

public class TrimExample {
    public static void main(String[] args) {
        String message = "   Hello, World!   ";

        String trimmedMessage = message.trim();

        System.out.println("Original message: '" + message + "'");
        System.out.println("Trimmed message: '" + trimmedMessage + "'");
    }
}

Output:

Original message: '   Hello, World!   '
Trimmed message: 'Hello, World!'

Handling Strings Without Leading or Trailing Whitespace

The trim method will return the original string if there are no leading or trailing whitespace characters.

Example

public class TrimExample {
    public static void main(String[] args) {
        String message = "Hello, World!";

        String trimmedMessage = message.trim();

        System.out.println("Original message: '" + message + "'");
        System.out.println("Trimmed message: '" + trimmedMessage + "'");
    }
}

Output:

Original message: 'Hello, World!'
Trimmed message: 'Hello, World!'

Comparison Before and After Trimming

You can use the trim method to ensure consistent comparisons by removing leading and trailing whitespace.

Example

public class TrimExample {
    public static void main(String[] args) {
        String str1 = "Hello";
        String str2 = "   Hello   ";

        boolean areEqualBeforeTrim = str1.equals(str2);
        boolean areEqualAfterTrim = str1.equals(str2.trim());

        System.out.println("Are strings equal before trim? " + areEqualBeforeTrim);
        System.out.println("Are strings equal after trim? " + areEqualAfterTrim);
    }
}

Output:

Are strings equal before trim? false
Are strings equal after trim? true

Conclusion

The String.trim() method in Java is used for removing leading and trailing whitespace from a string. By understanding how to use this method, you can efficiently clean up and format strings in your Java applications. Whether you are handling user input, preparing data for processing, or ensuring consistent string comparisons, the trim method provides a reliable solution for these tasks.