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## Java Double Vs Long: Java Explained

Java is a programming language with a wide array of applications. Its versatility in terms of data types has a major influence on how developers write code, as programming can often require precision dependent on the data sent to the computer. Here, we look into two distinct data types, Double and Long, and compare them to determine when to best use each of them.

## What is a Java Double?

A Java Double is a 64-bit double-precision floating-point data type. This type is able to represent both integers and fractions with high precision. The range of numerical values is represented between 4.9e-324 and 1.8e+308; with fifteen decimal digits of precision for any number within that range.

Java Double is a useful data type for applications that require a high degree of accuracy, such as scientific and financial calculations. It is also commonly used for storing large numbers, such as those used in cryptography. Additionally, Java Double is often used for representing decimal values, such as currency, as it can accurately represent values with a large number of decimal places.

## What is a Java Long?

On the other hand, a Java Long is an 8-byte signed two’s complement integer. Java Long integers range from -2^63 to 2^63-1 (-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807).

Java Longs are commonly used when a larger range of values is needed than what is provided by the Java Integer type. They are also used when a more precise representation of a number is needed, as they can store numbers with up to 19 digits of precision. Java Longs are also used when a larger range of values is needed than what is provided by the Java Integer type.

## Differences Between Java Double and Long

The main difference between Java Double and Long data types is that doubles can represent fractions whereas longs represent only integer values. Doubles are precise up to 15 decimal places, whereas longs store integers that are accurate up to 2^63 numbers. As such, trying to save an integer value into a double data type in Java will either lead to rounding errors or other unexpected results. Doubles are also faster to execute than longs, hence it may be beneficial to use them for tasks that require high performance.

When dealing with large numbers, it is important to consider the range of values that each data type can store. For example, a double can store values up to 1.7e308, while a long can store values up to 9223372036854775807. Therefore, if the value exceeds the range of a long, it is necessary to use a double instead. Additionally, when dealing with large numbers, it is important to consider the memory usage of each data type. Doubles require more memory than longs, so it is important to consider the memory requirements of the task before deciding which data type to use.

## When to Use Java Double and Long

Since doubles can represent both integers and fractions, they are ideal for calculations involving mathematical operations like addition, subtraction, multiplication and division. They can also be used for trigonometric and algebraic functions since they allow precise representation of fractional values up to fifteen decimal places. For tasks that require integers, Long is the optimal type. Noting that Java Long also has better performance than doubles when used in loops, it is also the most suitable type for arrays and loop performance.

When dealing with large numbers, Long is the preferred type as it can store numbers up to nine quintillion. This makes it ideal for tasks such as cryptography, where large numbers are used to generate secure keys. Additionally, Long is the best choice for tasks that require precise calculations, such as financial calculations, as it can store numbers up to eighteen decimal places.

## The Advantages of Using Java Double and Long

Using Java Double and Long data types offers the following advantages:

• High precision: Doubles offer 15 decimal digits and longs provide accuracy up to 2^63 numbers.
• Versatility: Either type may be used depending on the task.
• Fast execution: Longs execute faster than doubles.

In addition, Java Double and Long data types are compatible with most operating systems, making them a great choice for cross-platform development. They are also easy to use, with a simple syntax that makes them accessible to developers of all skill levels.

## The Disadvantages of Using Java Double and Long

Using Java Double and Long data types also has some drawbacks:

• Memory limits: Doubles may exceed memory limits since they occupy more space than longs.
• Performance: Long loops often suffer from slow performance when using doubles.
• Type conversion: If an integer is stored as a double, then unexpected results may occur.

In addition, doubles are not as precise as longs, and may lead to rounding errors when performing calculations. Furthermore, doubles are not suitable for storing currency values, as they can lead to discrepancies due to the lack of precision.

## How to Convert Between Java Double and Long

Converting between Java Double and Long is done using the predefined constants in the java.lang.Double and java.lang.Long classes. The syntax is as follows:

// convert from double to long
long l1 = (long) d1;

// convert from long to double
double d1 = (double) l1;

It is important to note that when converting from double to long, the decimal portion of the double will be truncated. Therefore, it is important to consider the precision of the data when performing this conversion.

## Common Pitfalls to Avoid When Using Java Double and Long

When using Java double or long variables, it is important to bear in mind that longs are better suited for holding integers as they may overflow when storing decimals. As such, trying to assign integers to doubles may lead to unexpected results or loss of accuracy.

Additionally, when converting values between the two types it is important to pay attention to the range of each data type. If an integer exceeds the range of Java Long and it is not changed manually then it will result in an overflow error. The additional precision offered by doubles may lead to memory constraints if such an overflow occurs.

In conclusion, while both Java Double and Long are highly useful data types, it is important to take into consideration the range of values each type can hold as well as their respective pros and cons for each particular scenario. Knowing the basics of each data type will ensure code robustness and accuracy in the long run.

It is also important to note that Java Double and Long are not interchangeable and should be used for different purposes. For example, Long should be used for storing integers, while Double should be used for storing decimals. Using the wrong data type can lead to unexpected results and should be avoided.

#### Anand Das

Anand is Co-founder and CTO of Bito. He leads technical strategy and engineering, and is our biggest user! Formerly, Anand was CTO of Eyeota, a data company acquired by Dun & Bradstreet. He is co-founder of PubMatic, where he led the building of an ad exchange system that handles over 1 Trillion bids per day.

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