String toUpperCase()

The toUpperCase() method in java is a part of the String class and is used to convert all characters of a string to uppercase. This method returns a new string with all characters converted to uppercase while leaving any characters that are already uppercase unchanged.

The basic syntax of the toUpperCase() method is as follows:

String toUpperCase()

Here’s how you can use it:

String original = "Hello World";
String uppercase = original.toUpperCase(); // "HELLO WORLD"

In this example, the toUpperCase() method is called on the string "Hello World", and it returns a new string with all characters converted to uppercase.

Keep in mind the following:

• The toUpperCase() method doesn’t modify the original string. Instead, it creates a new string with the uppercase representation of the characters.
• This method uses the default locale’s rules for converting characters to uppercase. If you need to perform case conversion according to a specific locale, you can use the overloaded version of this method that accepts a Locale argument:

  String toUpperCase(Locale locale)

For example:

  String original = "übermensch";
  String uppercase = original.toUpperCase(Locale.GERMAN); // "ÜBERMENSCH"

• Some characters might have multiple uppercase equivalents in different locales. The conversion behavior might differ based on the rules of the locale.

Here are a few more examples:

String str1 = "Java";
String str2 = "UpPeRcAsE";
String str3 = "ThIs Is A MiXeD CaSe StRiNg";

String uppercase1 = str1.toUpperCase();      // "JAVA"
String uppercase2 = str2.toUpperCase();      // "UPPERCASE"
String uppercase3 = str3.toUpperCase();      // "THIS IS A MIXED CASE STRING"

The toUpperCase() method is particularly useful when you need to perform case-insensitive string comparisons or when you want to ensure consistent case usage in your application, regardless of the input.