How do I format a long integer as a string without separator in Java?

java

string-formatting

java-8

best-practices

byNikita Barsukov·Sep 9, 2024

Use the Long.toString(long n) method to swiftly convert a long integer to a string, completely void of separators:

long number = 123456789L;
String formatted = Long.toString(number);
// Output: "123456789"
// Who'd of thunk "123456789" would suit a phone number!😜

Four words: Direct, Simple. Efficient, Effective.

Going beyond – Additional methods

String.format() - Another Runner

The String.format() method provides another compact solution:

String formatted = String.format("%d", number);
// Output: "123456789"
// I don't "string along", trust me 😁

With "%d", numbers are formatted directly sans any extra symbols. Quick conversions? No external libraries needed!

DecimalFormat - Flexibility for the win

Explore DecimalFormat for custom numeric formatting:

DecimalFormat formatter = new DecimalFormat("#");
String formatted = formatter.format(number);
// Output: "123456789"
// DecimalFormat, because numbers also fancy custom attire sometimes 🎩

While verbose, DecimalFormat opens doors to precision and complexity.

Java.util.Formatter - The control freak

For the utmost detailed control over numeric formatting, meet java.util.Formatter.

Formatter formatter = new Formatter();
String formatted = formatter.format("%d", number).toString();
// Output: "123456789"
// Apparently, Formatter also "formats" the time it takes 😂

Indeed a power-tool, but might be overkill for our task.

MessageFormat.format - Your formatting personalizer

MessageFormat.format() caters to choice-specific formatting:

String formatted = MessageFormat.format("{0,number,#}", number);
// Output: "123456789"
// Format styles than the number of coffees at Starbucks? No problem! ☕

Especially fit for dynamic or locale sensitive formatting.

Concatenation - A simple trick

To convert a long to a string, we can use concatenation:

String formatted = "" + number;
// Yet it's like ordering a steak at a vegan restaurant. Mind the inconspicuous! 🥩

While it works, performance-wise, it's a lousy player. It confuses readers and during compilation, may lead to StringBuffer or StringBuilder involvements.

Landing the optimal method

For the simplest conversion

Long.toString() is a catch:

Straight-out-of-the-box efficient.
Restrains unnecessary overhead.

For adaptable formatting

DecimalFormat and java.util.Formatter for:

Intricate number arrangements.
Special rounding needs.
Locale-based traditions.

Tackling diverse conditions

MessageFormat.format() is a hero:

Different formatting styles.
Locale-oriented formatting.
Dependency-based formatting instructions.

Remember, context and practical relevance make the judge. Yes, community opinions help, but so does your own assessment on simplicity and performance.

A Balanced Approach to Coding

Strive to balance:

Clarity: Going with what's simple and easy to read.
Performance: Opting for direct methods, avoiding complex alternatives.
Maintainability: Keep an eye on the future. Today's simplicity could be tomorrow's complexity.