In Java, a `DataOutputStream` is used to write primitive data types (such as `int`, `double`, `float`, etc.) to an output stream in a machine-independent way. When storing a `double` using `DataOutputStream`, it is typically stored in the IEEE 754 format, which is a standard for representing floating-point numbers.
Here’s how a `double` is stored using `DataOutputStream`:
1. Double Representation: A `double` in Java is a 64-bit (8-byte) floating-point number, following the IEEE 754 double-precision format. This format includes:
– 1 bit for the sign (0 for positive, 1 for negative)
– 11 bits for the exponent (with a bias of 1023)
– 52 bits for the fraction (also called the significand or mantissa)
2. Storing the Double: When you use the `writeDouble(double v)` method from `DataOutputStream`, the `double` is serialized to the stream as 8 bytes. The Java `DataOutputStream` handles converting the `double` to its IEEE 754 binary representation.
Here is an example:
“`java
import java.io.;
public class WriteDoubleExample {
public static void main(String[] args) {
try (DataOutputStream dos = new DataOutputStream(new FileOutputStream(“example.dat”))) {
double value = 123.456;
dos.writeDouble(value); // Writes the double as 8 bytes
System.out.println(“Double value written to file.”);
} catch (IOException e) {
e.printStackTrace();
}
}
}
“`
In this example:
– The `writeDouble()` method writes the 64-bit binary representation of the `double` value to the file.
– Internally, the `double` value `123.456` is converted into its IEEE 754 binary format and written as 8 bytes to the output stream.
Summary:
– A `double` is stored in 8 bytes (64 bits) following the IEEE 754 standard.
– `DataOutputStream.writeDouble(double v)` serializes the `double` as 8 bytes to the output stream, allowing it to be read later in a consistent manner across different platforms.
