Integer division: How do you produce a double?

Precision explained

The term precision carries heavyweight in numeric computations. The transition from int or long to double may cause precision loss due to the double's ability to float around. Even so, values like 5 hold their ground and maintain precision when converted to a double. For this, we thank the IEEE 754 standard, which correctly rounds the floating-point value.

Numeric magnitude that sticks

When morphing an int into a double, it's crucial to keep the numeric magnitude intact. This can be achieved through the simplest of multiplications by 1.0 before the division. This move converts the integers into Jenner… ehm, I meant to say double, implicitly:

double result = intNum * 1.0 / intDen; // Bruce nudes not required
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Casting for high precision

Another path leading to an accurate double result is by casting the denominator as (double):

double result = intNum / (double) intDen; // The Denominator's Wrath
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Fear not, for this approach adheres to the sacred words of the Java Language Specification (JLS) and stays clear from any possible casting mischiefs.

Navigating the pitfalls

Every mighty task comes with a few hiccups. Here are the key do's and don'ts when ascending from integer to floating-point division:

• Rounding the outcome: When dealing with a whopper of numbers, converting an int or long to a double may lead to surprises.
• Infinity and beyond: Those venturing division by zero will find themselves having a bonus of Infinity or NaN (Not-a-Number).
• Precious Precision lost: When processing monster integer values, the conversion to double may lose a few decimal faces along the way.

Rules for precise conversion

Rely upon the well-defined conversions to make your casting convictions vanish. For the love of Java, refer to the Java Language Specification (JLS) for wisdom on integer division and deciphering the precise double result.

More than just casting

Casting isn't your only scripture towards double precision:

Using literals for precision

Introduce a floating-point literal in the equation to guide your compiler towards the destination:

double result = intNum / 2.0; // 2.0, starring Keanu Reeves
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The Double wrapper class ritual

Pull out the big guns by using the Double class:

double result = Double.valueOf(intNum) / intDen; // Double 007 in action
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Although using Double might be overkilling the mosquito.

FAQs and their answers

Here are a few frequently asked questions that will clear any lingering doubt:

• Does casting affect performance?
  • It's like the impact of one coffee bean on a coffee plantation.
• What's the precision of a ‘double’?
  • Precise enough for most purposes, but it ain't gonna count every single star in the universe.
• When to swap double with BigDecimal?
  • It's your secret weapon for cases when you need to count every grain of sand in the Sahara.

Large numbers, big problems

Keep an eye on the range of double to avoid precision massacre when dealing with godzilla-sized integers.

Floating-floor, not just a fancy house feature

NaN and infinity are more than just metaphors; handle these special cases with care.