String trim() method - Syntax and Examples

Learn how to use the Java String `trim()` method. This tutorial covers syntax, parameters, return values, and provides practical examples.

This reference explains String trim() method - Syntax and Examples through its syntax, examples and boundaries. Use the linked course lessons when the surrounding Java concepts are unfamiliar.

Sometimes your strings have leading or trailing whitespace – spaces, tabs, newlines – that you don't want. The `trim()` method provides a simple way to remove this unwanted whitespace from the beginning and end of a string without affecting the characters in between.

public String trim()

The trim() method returns a new string with leading and trailing whitespace removed.

This example shows how to trim a simple string containing spaces at the beginning and end.

public class TrimExample {
  public static void main(String[] args) { 
    String str = "   Hello, World!   ";
    String trimmedStr = str.trim();
    System.out.println("Original String: \"" + str + "\"");
    System.out.println("Trimmed String: \"" + trimmedStr + "\"");
  }
}

Original String:   Hello, World!   
Trimmed String: Hello, World!

In this example, the leading and trailing spaces are removed from str before assigning it to trimmedStr. The original string remains unchanged.

This demonstrates how `trim()` handles tabs and newlines, not just spaces.

public class TrimExample2 {
  public static void main(String[] args) { 
    String str = "\t\n Hello World \n\t";
    String trimmedStr = str.trim();
    System.out.println("Original String: \"" + str + "\"");
    System.out.println("Trimmed String: \"" + trimmedStr + "\"");
  }
}

Original String: 	
 Hello World 

Trimmed String: Hello World 

Notice how the tabs and newlines at both ends of the string are removed. The content between these characters remains unaffected.

This example illustrates what happens when you try to trim an empty string or a string containing only whitespace.

public class TrimExample3 {
  public static void main(String[] args) { 
    String str1 = "";
    String str2 = "   \t\n\t  ";
    String trimmedStr1 = str1.trim();
    String trimmedStr2 = str2.trim();
    System.out.println("Original String 1: \"" + str1 + "\"");
    System.out.println("Trimmed String 1: \"" + trimmedStr1 + "\"");
    System.out.println("Original String 2: \"" + str2 + "\"");
    System.out.println("Trimmed String 2: \"" + trimmedStr2 + "\"");
  }
}

Original String 1: 
Trimmed String 1: 
Original String 2:      	  
Trimmed String 2: 

When trimming an empty string, you get an empty string back. When trimming a string containing only whitespace, the result is also an empty string.

This example shows how to use `trim()` when getting input from a user, which often contains leading or trailing spaces.

import java.util.Scanner;

public class TrimExample4 {
  public static void main(String[] args) { 
    Scanner scanner = new Scanner(System.in);
    System.out.print("Enter your name: ");
    String name = scanner.nextLine();
    String trimmedName = name.trim();
    System.out.println("Hello, " + trimmedName + "!");
    scanner.close();
  }
}

This code prompts the user for their name and then trims any leading or trailing spaces before displaying a greeting. This ensures that the displayed name is clean and professional.

Check the example’s types, inputs and documented behavior before copying it into an application. Some APIs require external libraries, files or platform services; consult their setup notes.

Related explanations: Java Data Types - Primitive and Non-Primitive, Java Class - Blueprint of Objects, Exceptions in Java Introduction.

Supporting documentation: Official Java learning guide.