Java String toUpperCase()

The Java String toUpperCase() method converts all characters in the string to upper case characters.

The syntax of the string toUpperCase() method is:

string.toUpperCase()

toUpperCase() Parameters

  • doesn't take any parameters

toUpperCase() Return Value

  • returns a string with all lower case letters converted to upper case

Example: Java toUpperCase()

class Main {
  public static void main(String[] args) {
    String str1 = "Learn Java";
    String str2 = "Java123";

    // convert to upper case letters
    System.out.println(str1.toUpperCase()); // "LEARN JAVA"
    System.out.println(str2.toUpperCase()); // "JAVA123"
  }
}

As you can see from the above example, toUpperCase() converts all lower case letters to upper case letters.


toUpperCase() With Locale Parameter

The toUpperCase() method can also take a locale as an argument. This allows you to convert all characters in a string to upper case using the given Locale (such as: Turkish, Lithuanian etc.) rules.

Its syntax is:

string.toUpperCase(Locale locale)

If you do not pass the locale parameter, the default locale, Locale.getDefault(), is used.

To learn more, visit Java toUpperCase() With Locale.


To convert all characters in a string to lower case letters, use the Java String toLowerCase() method.