How do I convert from int to Long in Java?

java

autoboxing

null-handling

type-casting

byAnton Shumikhin·Aug 31, 2024

To convert int to Long in Java, you can either use Long.valueOf() method or let autoboxing handle it:

int intValue = 42;
Long longValue = Long.valueOf(intValue); // Long and explicit just like marriage
Long autoBoxedValue = intValue; // Close and personal like a best friend

Long.valueOf() is explicit and autoboxing is implicit. Both methods serve well for int to Long conversion.

Best techniques to convert int to Long

When you're about to convert int to Long, certain techniques can streamline the process and keep your code clean:

Long.valueOf() utilization: Helps in efficient memory utilization. Caches those sneaky little int constants you use so often. Don't we all just love performance?
Avoid typecasting: Direct casting from int to Long can throw a ClassCastException party, and trust me, that's one party you don't want an invite to.

Navigating through nulls and defaults

In conversion, you might rub shoulders with nulls or have to dance with defaults:

Default values: While converting int that might come from potentially nullable sources, always have a fallback option like ordering vegetarian at a barbecue.
Null handling: NullPointerException is like that annoying fly in your soup, so keep your code prepared for null scenarios and enjoy your code soup!

Possible gotchas and caveats

Here are some hard-boiled truths for you:

Autoboxing gimmicks: Autoboxing is cool, but remember, it might throw surprise boxing matches when performance is the title at stake.
Range rifts: Just like the wealth gap in society, Long can hold significantly higher values than int. When numbers start going crazy, think before you leap.

Ally with collections like ArrayList

While using Long with collections like ArrayList, focus on type incorporation:

Compatibility with ArrayList<Long>: Uniformity is charm! Ensure all numerics in an ArrayList are wearing the same type outfit.
Bulk conversion swagger: When converting entire array or List<Integer> to List<Long>, leverage Java streams or loops like a pro.

Dealing with specific conversion scenarios

For specific situations where you need to convert int to Long:

Manage sequence numbers in objects: Entities and ORM frameworks often mingle better with Long than an int.
Safeguard type progression: Design overloads or conversion methods for a smooth transition from int to Long.

Keeping conversion contextual

Context is key when working with conversions:

Smart Casting: Cast or convert according to the context like changing outfits based on occasion.
Architectural foresight: Make the conversion call at the right moment - architectural wisdom at its finest.

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