Create a string with n characters

java

string-creation

performance-optimization

code-readability

byNikita Barsukov·Oct 26, 2024

Create a String with n copies of a character:

Java 8: Stream and String constructor:

String repeated = new String(new char[n]).replace("\0", String.valueOf(ch));

Java 11+: Utilize .repeat():

String repeated = String.valueOf(ch).repeat(n);

Decoding string formation methods

To attain proficiency in string creation in Java, one should understand the broad range of approaches and their underpinnings. This section unravels various methodologies, revealing their internal mechanics and potential edge cases.

Benefits of `String.repeat()`

In Java 11, String.repeat() was introduced, simplifying string replication. It offers concise syntax and internal optimizations for efficient performance:

// String.repeat in action. Action heroes love repeat stunts!
String actionSeq = "*".repeat(50);

Using `Arrays.fill()` for character arrangement

Arrays.fill() swiftly converts a barren character array into a consistent string. It's your go-to tool for performance and clarity:

// Arrays.fill in action. As filling as a good meal!
char[] buffet = new char[n];
Arrays.fill(buffet, 'Z'); // 'Z' for zeal!
String fedUp = new String(buffet);

Leveraging third-party libraries

When dependencies on libraries like Apache Commons are already present in the project, take advantage of their battle-tested performance and reliability:

// Using StringUtils.repeat. Because why reinvent the wheel?
String repeated = StringUtils.repeat('x', 100);

Trust in the Java compiler

Embrace the Java compiler's power. While it might be tempting to compare methodologies, remember the Java compiler effectively optimizes code execution.

Performance vs readability: Choose your side

Writing code often involves making tough calls between performance and readability. This section helps you navigate these decisions.

Prioritizing maintainability

When readability speaks louder, opt for an approach that makes your code self-explanatory and maintainable:

// When space is not the final frontier!
String spaceOdyssey = " ".repeat(20);

When performance takes the lead

In situations where performance is the king, knowing the cost of each operation is crucial:

//  '#'. Because sometimes, performance rules!
char[] performanceGalore = new char[1000];
Arrays.fill(performanceGalore, '#');
String hashtagFrenzy = new String(performanceGalore);