Java String transform()

In this guide, you will learn about the String transform() method in Java programming and how to use it with an example.

1. String transform() Method Overview


The transform(Function<? super T,? extends R> function) method is a part of the String class in Java. This method allows the application of a function to the current string. The function should expect an argument of type String and produce an arbitrary type R.


<R> R transform(Function<? super String, ? extends R> function)


- function: The function to apply to the string.

Key Points:

- The method can be used to transform a string into another object of any desired type.

- It can be especially useful in chaining operations on strings.

- The method was introduced in Java 12.

2. String transform() Method Example

public class TransformExample {
    public static void main(String[] args) {
        String str = "java programming";

        // Transforming the string to uppercase
        String upperCaseStr = str.transform(String::toUpperCase);
        System.out.println("Uppercase String: " + upperCaseStr);

        // Transforming the string to its length
        Integer strLength = str.transform(String::length);
        System.out.println("String Length: " + strLength);

        // Chaining transformations
        String reversedUpperCaseStr = str.transform(String::toUpperCase)
                                        .transform(s -> new StringBuilder(s).reverse().toString());
        System.out.println("Reversed Uppercase String: " + reversedUpperCaseStr);


Uppercase String: JAVA PROGRAMMING
String Length: 17
Reversed Uppercase String: GNIMMARGORP AVAJ


In this example, we have a string str. We use the transform() method to change it to uppercase and print the result. 

Next, we use transform() to convert the string to its length, an Integer, and print it. 

Finally, we chain two transform() operations to convert the string to uppercase and then reverse it, printing the final result. The output demonstrates the various transformations applied to the original string.