Java String toLowerCase() with Examples

Java String toLowerCase() method is used and operated over a string where we want to convert all letters to lowercase in a string. In this article, we will learn to convert Uppercase into Lowercase using toLowerCase() in Java.

Methods of String toLowerCase()

There are two types of toLowerCase() methods as follows: 

1. toLowerCase()
2. toLowerCase(Locale loc): Converts all the characters into lowercase using the rules of the given Locale.

Locale in Java(Internal Working of toLoweCase())

The Locale class is part of java.util package. It is used for extracting and manipulating the information. Locale object represents a geographical, political, or cultural region.

Example Statement:

// Creates a Locale for the English language
Locale locale1 = new Locale("en"); 

It plays a vital role in toLowerCase() conversion where it checks the elements and helps to convert them into Lower Case. To know more about the topic refer to Locale article.

Note: Internally toLowerCase() works in similar way as toLowerCase(Locale.getDefault()) method.

Syntax of toLowerCase()

public String toLowerCase ()
public String toLowerCase (Locale loc)

The package view of the method is as follows: 

--> java.util Package
    --> String Class
        --> toLowerCase() Method 

Parameters

• Locale value to be applied.

Return Value

• Returns a string in lowercase letter.

Example Java toLowerCase()

Example 1:

java

// Java Program to Demonstrate Working of
// toLowerCase() Method of String Class

// Importing required classes
import java.util.*;

// Main class
class GFG {

    // Main driver method
    public static void main(String args[])
    {

        // Custom input string
        String s = "Geeks for Geeks";

        // Converting string s to lowercase letter
        String s2 = s.toLowerCase();

        // Printing the lowercase string corresponding
        // to input string
        System.out.println(s2);
    }
}

Output

geeks for geeks

Example 2:

java

// Java program to demonstrate Working of toLowerCase()
// Method present inside Locale class

// Importing required classes
import java.util.Locale;

// Main class
class GFG {

    // Main driver method
    public static void main(String args[])
    {
        // Custom input string
        String s = "I Know YOI Bui You Don't Know ME";

        // Locales with the language "tr" for TURKISH
        //"en" for ENGLISH is created
        Locale TURKISH = Locale.forLanguageTag("tr");
        Locale ENGLISH = Locale.forLanguageTag("en");

        // Converting string s to lowercase letter
        // using TURKISH and ENGLISH language
        String gfg2 = s.toLowerCase(TURKISH);
        String gfg3 = s.toLowerCase(ENGLISH);

        // Printing above string
        System.out.println(gfg2);
        System.out.println(gfg3);
    }
}

Output

ı know yoı bui you don't know me
i know yoi bui you don't know me