In Java, when you need to store a 64-bit value, you have two main data types to choose from: **long** and **double**. Let’s take a closer look at each of them and understand their characteristics.

## The long Data Type

The **long** data type is a 64-bit signed integer. It can store values ranging from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 (inclusive).

When declaring a variable of type **long**, you need to append the letter ‘L’ or ‘l’ at the end of the value to indicate that it is a long literal. For example:

```
long myLong = 1234567890L;
```

You can perform various mathematical operations on long values just like with any other numeric data type in Java.

## The double Data Type

The **double** data type is a 64-bit floating-point number. It can store decimal values with a higher precision compared to integers.

A double value can represent numbers ranging from approximately ±4.9 x 10^{-324} to ±1.8 x 10^{308}. However, it is important to note that double values are not capable of representing every possible decimal accurately due to the limitations of floating-point arithmetic.

To declare a variable of type **double**, use the following syntax:

```
double myDouble = 3.14159;
```

You can perform mathematical operations on double values as well as utilize various mathematical functions provided by the Java Math class.

## Choosing the Right Data Type

Now that you know about long and double, you might wonder which one to use for storing a 64-bit value. The answer depends on your specific requirements.

If you need to work with whole numbers and do not require decimal precision, using the **long** data type is recommended.

It ensures accuracy and provides a wider range of values for integers.

On the other hand, if you need to deal with fractional or decimal values, the **double** data type is more suitable. Keep in mind its limitations when it comes to precise decimal representation.

### Summary

- The
**long**data type is a 64-bit signed integer, suitable for whole numbers. - The
**double**data type is a 64-bit floating-point number, suitable for decimal values. - The choice between long and double depends on the specific requirements of your program.

In conclusion, when you need to store a 64-bit value in Java, consider whether it is an integer or a decimal. Choose the appropriate data type – long for integers and double for decimals – based on your program’s needs. By understanding the characteristics of each data type, you can ensure accurate representation and efficient computation in your Java programs.