DoubleBuffer

DoubleBuffer is a buffer class from java.nio that manages sequences of 64-bit double-precision floating-point numbers (double). It is used for fast, efficient, and flexible manipulation of double data in memory, suitable for high-performance scientific computations, graphics, or real-time analytics.DoubleBuffer is abstract. Use static allocate() and wrap()  factory methods to get instances.

Commonly Used Methods

Simple Program: Storing Double-Precision Scientific Data

import java.nio.DoubleBuffer;

public class DoubleBufferSimple {
    public static void main(String[] args) {
        // Allocate DoubleBuffer for 4 double values
        DoubleBuffer buffer = DoubleBuffer.allocate(4);

        // Put some double precision data points (e.g., sensor readings)
        buffer.put(12.3456789);
        buffer.put(98.7654321);
        buffer.put(56.7890123);
        buffer.put(34.5678901);

        // Prepare buffer for reading
        buffer.flip();

        System.out.println("Double precision data points:");
        while (buffer.hasRemaining()) {
            System.out.println(buffer.get());
        }
    }
}

Problem Statement 

Mahesh has a physics experiment that records energy values as double precision floating points.
LotusJavaPrince is tasked to:

• Accept an array of 8 energy values (double[]).
• Store the values in a DoubleBuffer.
• Identify and print only those energy values greater than 50.0 units.
• Use buffer APIs only (no direct array access for filtering).

import java.nio.DoubleBuffer;

public class EnergyFilter {
    public static void main(String[] args) {
        double[] energyValues = { 45.5, 67.8, 32.1, 99.9, 50.0, 75.2, 48.6, 100.5 };

        // Wrap the array into DoubleBuffer
        DoubleBuffer buffer = DoubleBuffer.wrap(energyValues);

        System.out.println("Energy values > 50.0:");

        for (int i = 0; i < buffer.limit(); i++) {
            double val = buffer.get(i);
            if (val > 50.0) {
                System.out.println("Index " + i + " → " + val);
            }
        }
    }
}

Output

Energy values > 50.0:
Index 1 → 67.8
Index 3 → 99.9
Index 5 → 75.2
Index 7 → 100.5Code language: CSS (css)

The DoubleBuffer class in Java NIO provides a specialized and efficient way to handle sequences of 64-bit double-precision floating-point numbers. As a subclass of the abstract Buffer class, it supports the essential buffer properties — position, limit, capacity, and mark — optimized for double data.

DoubleBuffer is especially valuable in scientific computing, financial modeling, and any domain requiring high-precision numerical calculations. It supports both heap-based and direct buffers, allowing for flexible memory management and improved performance in I/O operations.

Key features include relative and absolute get() and put() methods, bulk data transfers, and buffer manipulation methods like slicing, duplicating, and compacting, providing fine control over double data handling.