Java Program to Convert String to Title Case

Use Java to convert a string to title case by splitting the string into words, capitalizing the first letter of each word with Character.toUpperCase(), and joining them back; for example, String titleCase = Arrays.stream(input.split(" ")).map(word -> Character.toUpperCase(word.charAt(0)) + word.substring(1).toLowerCase()).collect(Collectors.joining(" "));.

Examples

Inputhello world

OutputHello World

Inputjava PROGRAMMING language

OutputJava Programming Language

Input multiple spaces here

OutputMultiple Spaces Here

How to Think About It

To convert a string to title case, first split the string into individual words by spaces. Then, for each word, change the first letter to uppercase and the rest to lowercase. Finally, join all the words back together with spaces to form the title-cased string.

Algorithm

1

Get the input string.

2

Split the string into words using space as a separator.

3

For each word, convert the first character to uppercase and the rest to lowercase.

4

Join all the processed words back into a single string separated by spaces.

5

Return or print the resulting title case string.

Code

java

import java.util.Arrays;
import java.util.stream.Collectors;

public class TitleCaseConverter {
    public static String toTitleCase(String input) {
        return Arrays.stream(input.trim().split("\\s+"))
                .map(word -> word.isEmpty() ? word : Character.toUpperCase(word.charAt(0)) + word.substring(1).toLowerCase())
                .collect(Collectors.joining(" "));
    }

    public static void main(String[] args) {
        String input = "java PROGRAMMING language";
        String titleCase = toTitleCase(input);
        System.out.println(titleCase);
    }
}

Output

Java Programming Language

Dry Run

Let's trace the input "java PROGRAMMING language" through the code

1

Trim and split input

Input string trimmed: "java PROGRAMMING language"; split into words: ["java", "PROGRAMMING", "language"]

2

Process each word

For "java": first char 'j' to uppercase 'J', rest "ava" to lowercase "ava" → "Java" For "PROGRAMMING": first char 'P' uppercase 'P', rest "ROGRAMMING" lowercase "rogramming" → "Programming" For "language": first char 'l' uppercase 'L', rest "anguage" lowercase "anguage" → "Language"

3

Join words

Join processed words with spaces → "Java Programming Language"

Word	First Char Uppercase	Rest Lowercase	Result
java	J	ava	Java
PROGRAMMING	P	rogramming	Programming
language	L	anguage	Language

Why This Works

Step 1: Splitting the string

We split the input string by spaces using split("\\s+") to get each word separately.

Step 2: Capitalizing each word

For each word, we use Character.toUpperCase() on the first letter and toLowerCase() on the rest to ensure proper title case.

Step 3: Joining words back

We join all the processed words with spaces using Collectors.joining(" ") to form the final title case string.

Alternative Approaches

Using StringBuilder and manual loop

java

public class TitleCaseManual {
    public static String toTitleCase(String input) {
        String[] words = input.trim().split("\\s+");
        StringBuilder titleCase = new StringBuilder();
        for (String word : words) {
            if (word.length() > 0) {
                titleCase.append(Character.toUpperCase(word.charAt(0)))
                         .append(word.substring(1).toLowerCase())
                         .append(" ");
            }
        }
        return titleCase.toString().trim();
    }

    public static void main(String[] args) {
        System.out.println(toTitleCase("hello world"));
    }
}

This approach uses a simple loop and StringBuilder, which is easy to understand and efficient for beginners.

Using Apache Commons Lang WordUtils

java

import org.apache.commons.lang3.text.WordUtils;

public class TitleCaseApache {
    public static void main(String[] args) {
        String input = "java PROGRAMMING language";
        String titleCase = WordUtils.capitalizeFully(input);
        System.out.println(titleCase);
    }
}

This method uses a library to handle title casing, which is very concise but requires adding an external dependency.

Complexity: O(n) time, O(n) space

Time Complexity

The program processes each character once when splitting and converting words, so time complexity is O(n), where n is the length of the input string.

Space Complexity

Extra space is used to store the split words and the output string, so space complexity is O(n).

Which Approach is Fastest?

The manual loop with StringBuilder is generally fastest and uses minimal overhead, while stream-based and library methods are more readable but may have slight overhead.

Approach	Time	Space	Best For
Stream API with map	O(n)	O(n)	Readable and concise code
Manual loop with StringBuilder	O(n)	O(n)	Performance and simplicity
Apache Commons WordUtils	O(n)	O(n)	Quick solution with external library