How to convert / cast long to String?

java

string-conversion

long-literals

number-format-exception

byAnton Shumikhin·Aug 16, 2024

Here's the fastest way to convert a long to a String. Use the Long.toString(long) method:

long impressiveLongNumber = 123456789L; // "Impressive, huh?" 
String str = Long.toString(impressiveLongNumber); // Now you see it in text! 🚀

Short, sweet, and efficient!

Useful Conversion Methods

Along with Long.toString(long), there are other methods to transform your long to a String:

// Using String.valueOf(long)
String strValueOf = String.valueOf(impressiveLongNumber); // "I swear it's still the same number."

// The "old school" concatenation way
String strConcat = "" + impressiveLongNumber; // Like sticking a label on your number

// The null-safe way
String strObjects = Objects.toString(impressiveLongNumber, null); // "It's okay if you forgot the long. I got you."

String.valueOf(long) is a diligent method doing the job pretty well. As for concatenation, it's easy but not the fastest kid on the block. Anyway, if performance isn't your Achilles' heel, feel free to use it! The Objects.toString(long, null) ensures that even if you pass a null number, the program won't give up on you.

Conversion Cycle: Back to Long

Beware! When you're coming back home (i.e., converting from String to long), things can get tricky.

try {
    long parsedLong = Long.parseLong(str);
    // "I told you, we'd be back." (Arnold Schwarzenegger voice)
} catch (NumberFormatException e) {
    // "I'll be back...with a valid number." (Still Arnold Schwarzenegger voice)
}

Use Long.parseLong(String) to reverse engineer into a long. But remember, if the text doesn't look like a number, NumberFormatException will come knocking. So, brace for impact!

Playing with Dates and Literals

// Need a date? Use SimpleDateFormat
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd"); // "2023-12-23" 
Date theFuture = new Date(impressiveLongNumber); // "Roads? Where we’re going, we don’t need roads." - Back to the Future reference
String strDate = format.format(theFuture);

// Explicitly marking `long` literals. Because clarity matters!
long explicitLong = 123456789L; // An 'L'. Because who knows, it maybe an int. Better safe than sorry!

Again, SimpleDateFormat sweeps in to save the day when you're dealing with dates or times. And when you're dealing with number literals, adding an L at the end is like marking your own territory.

Unexpected Updates: Is your application ready?

When it comes to the Long class, Long.toString() is your knight in shining armor for safer String conversions.

Data loss can be sneaky, so always double-check when converting.
Testing both your conversions and patience will save you a world of trouble.
For the brave souls dabbling in Blackberry apps, hats off to you and beware of the DateField.

Jumpy exceptions like NumberFormatException would love to crash your party, so handle them carefully.

Swag of Long Literals

long longLiteral = 9223372036854775807L; // "Length does matter."

Explicitly marking literals clears doubt and aids the compiler. It's all about context.

Everyday Scenario

Logging systems crave numeric IDs in strings for log messages.
On a GUI where long values are to be displayed, remember to put labels!
If an external system requires numeric values as query parameters or in message bodies, play by their rules.
Data serialization and deserialization with JSON or XML often need long to String conversions.