Java String toLowerCase​() Examples to convert string to lowercase

1. Introduction

In this article, You'll be learning how to convert each character in the string into a lower case.

This is very easy and can be done using String class toLowerCase() method which returns a new String after converting every character to the lowercase.

2. Java String toLowerCase​() Syntax

Below is the syntax from java api documentation.

public String toLowerCase​()
public String toLowerCase​(Locale locale)

This method does not take any argument but returns a new String with lowercase contents.

How to convert String to lowercase?

3. Java String toLowerCase​() Example - To convert String to Lowercase

package com.javaprogramto.w3schools.programs.string;

public class StringToLowercase {

    public static void main(String[] args) {

        String string = "HELLO WELCOME TO THE JAVAPROGRAMTO.COM";
        String lowercaseStr = string.toLowerCase();

        System.out.println("Lowercase converted string : "+lowercaseStr);
    }
}

Output:

Lowercase converted string : hello welcome to the javaprogramto.com

4. Java String toLowerCase​() Locale Examples

By default, toLowerCase() does conversion internally based on the default locale from the computer or server.

toLowerCase(Locale.getDefault());

I have set the default locale as English in my machine so conversion is done for this locale;

But, if you want to for different locale then use the toLowerCase(Locale locale) overloaded method instead of the toLowerCase() method.

package com.javaprogramto.w3schools.programs.string;

import java.util.Locale;

public class StringToLowercase {

    public static void main(String[] args) {

        Locale defaultLocale = Locale.getDefault();
        System.out.println("Default locale : "+defaultLocale);

        String string = "I am Now Using the different locales";

        Locale french = Locale.forLanguageTag("co-FR");

        System.out.println("french loale : "+french);
        String lowercaseStr = string.toLowerCase(french);

        System.out.println("Lowercase converted string in French : "+lowercaseStr);

        Locale chineesLocale = new Locale("zh", "CN");

        String chineeslowerCase = string.toLowerCase(chineesLocale);
        System.out.println("Chinees locale string : "+chineeslowerCase);

    }

}

Output:

Default locale : en_US

french loale : co_FR

Lowercase converted string in French : i am now using the different locales

Chinees locale string : i am now using the different locales

5. Java String toLowerCase​() Internal Implementation

public String toLowerCase() {
    return toLowerCase(Locale.getDefault());
}

public String toLowerCase(Locale locale) {
    return isLatin1() ? StringLatin1.toLowerCase(this, value, locale)
                      : StringUTF16.toLowerCase(this, value, locale);
}

6. Conclusion

In this article,  We've seen how to convert the string to lowercase with the default locale and with custom locale for specified country.

All examples showed are over GitHub.