FastClipboard — Native Clipboard Access via JNI (2-3× Faster than Java AWT)

⚡ Ultra-fast native clipboard access — stable copy/paste without Java clipboard bugs

// Quick Start — Stable clipboard operations
FastClipboard clipboard = new FastClipboard();

// Copy text to clipboard
clipboard.setClipboardText("Hello, World!");

// Get text from clipboard
String text = clipboard.getClipboardText();

// Copy image to clipboard
int[] pixels = new int[100 * 100];
clipboard.setClipboardImage(100, 100, pixels);

// Copy file list to clipboard
String[] files = {"C:\\file1.txt", "C:\\file2.txt"};
clipboard.setClipboardFiles(files);

FastClipboard is a high-performance Java clipboard library that replaces java.awt.Toolkit.getDefaultToolkit().getSystemClipboard() with a native Windows backend using Win32 API calls. Built for stable text operations, image handling, file transfer, and format detection. Supports CF_UNICODETEXT, CF_DIB (images), and CF_HDROP (file lists) formats.

Keywords: java clipboard alternative, native clipboard jni, win32 clipboard api, fast copy paste java, clipboard stability, java clipboard bug fix, windows clipboard automation, jni clipboard, clipboard image support, file list clipboard

If you need reliable clipboard operations, image transfer, or file drag-and-drop without Java's clipboard bugs, FastClipboard delivers native-level performance with Java simplicity.

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Table of Contents

• Why FastClipboard?
• Key Features
• Performance Benchmarks
• Installation
• Quick Start
• API Reference
• Build from Source
• Platform Support
• Use Cases
• License

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Why FastClipboard?

java.awt.Toolkit.getDefaultToolkit().getSystemClipboard() is convenient but buggy:

• Clipboard ownership issues
• Intermittent failures
• Thread-safety problems
• Slow performance

FastClipboard solves this with:

• Direct Win32 API calls — OpenClipboard, GetClipboardData, SetClipboardData
• Stable operation — no ownership issues
• UTF-8/Unicode support — proper text encoding
• Minimal footprint — 1 header + 1 JNI file + 1 Java class
• 1-evening implementation — simple and maintainable

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Key Features

• Direct Win32 API access — stable clipboard operations
• Text support — UTF-8/Unicode text with proper encoding
• Image support — DIB format (CF_DIB) for bitmap images
• File list support — CF_HDROP format for file operations
• Format detection — check available clipboard formats
• Minimal footprint — small DLL, simple API
• MIT licensed — free for commercial use
• Windows-only — maximum performance on the most common platform

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Performance Benchmarks

Operation	Java AWT Clipboard	FastClipboard	Speedup
Set Text (1000 iterations)	~5000μs	~2000μs	2.5×
Get Text (1000 iterations)	~3000μs	~1500μs	2.0×
Full Cycle (1000 iterations)	~8000μs	~3500μs	2.3×

Measured on Windows 11, Intel Core i7, Java 17

Run the benchmark:

# Compile native DLL first
compile.bat

# Run benchmark
mvn compile exec:java -Dexec.mainClass="fastclipboard.Benchmark"

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Installation

Maven

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

<dependency>
    <groupId>com.github.andrestubbe</groupId>
    <artifactId>fastclipboard</artifactId>
    <version>1.0.0</version>
</dependency>

Gradle

repositories {
    maven { url 'https://jitpack.io' }
}

dependencies {
    implementation 'com.github.andrestubbe:fastclipboard:1.0.0'
}

Direct Download

Download the pre-built JAR with embedded native library:

📥 Download fastclipboard-1.0.0.jar (64 KB)

# Run directly
java -cp fastclipboard-1.0.0.jar fastclipboard.Demo

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Quick Start

Basic Usage

import fastclipboard.FastClipboard;

FastClipboard clipboard = new FastClipboard();

// Copy text to clipboard
boolean success = clipboard.setClipboardText("Hello, World!");

// Get text from clipboard
String text = clipboard.getClipboardText();
System.out.println("Clipboard: " + text);

// Check if clipboard has text
if (clipboard.hasClipboardText()) {
    System.out.println("Clipboard contains text");
}

// Clear clipboard
clipboard.clearClipboard();

Optional Clipboard Watcher (for instant reads)

Enable the watcher for 570× faster repeated clipboard reads via automatic caching:

FastClipboard clipboard = new FastClipboard();

// Enable watcher (opt-in, zero overhead when disabled)
clipboard.enableWatcher();

// First read fetches from clipboard (~500μs)
String text = clipboard.getClipboardText();

// Subsequent reads use cache (~1μs) - 570× faster!
for (int i = 0; i < 1000; i++) {
    String cached = clipboard.getClipboardText(); // No JNI call!
}

// Cache auto-invalidates when clipboard changes externally
// Disable when done
clipboard.disableWatcher();

When to use:

• Bots/Agents with frequent clipboard polling
• Vision pipelines reading clipboard repeatedly
• Any scenario with >100 reads/second

Zero overhead design:

• Disabled by default - no threads, no events
• Opt-in only when needed
• Automatically invalidates cache on clipboard changes

Format Detection

// Check if specific format is available
if (clipboard.isFormatAvailable(FastClipboard.CF_UNICODETEXT)) {
    System.out.println("Unicode text available");
}

// Get number of available formats
int formatCount = clipboard.getFormatCount();
System.out.println("Available formats: " + formatCount);

Image Operations

// Copy image to clipboard (RGBA pixel data)
int width = 100;
int height = 100;
int[] pixels = new int[width * height];
// Fill with RGBA pixel data (0xAARRGGBB)
for (int i = 0; i < pixels.length; i++) {
    pixels[i] = 0xFFFF0000; // Red pixels
}
boolean success = clipboard.setClipboardImage(width, height, pixels);

// Get image from clipboard
int[] imageData = clipboard.getClipboardImage();
if (imageData != null) {
    int imgWidth = imageData[0];
    int imgHeight = imageData[1];
    int[] imgPixels = new int[imageData.length - 2];
    System.arraycopy(imageData, 2, imgPixels, 0, imgPixels.length);
}

// Check if clipboard has image
if (clipboard.hasClipboardImage()) {
    System.out.println("Clipboard contains image");
}

File List Operations

// Copy file list to clipboard
String[] files = {"C:\\path\\to\\file1.txt", "C:\\path\\to\\file2.txt"};
boolean success = clipboard.setClipboardFiles(files);

// Get file list from clipboard
String[] clipboardFiles = clipboard.getClipboardFiles();
if (clipboardFiles != null) {
    for (String file : clipboardFiles) {
        System.out.println("File: " + file);
    }
}

// Check if clipboard has file list
if (clipboard.hasClipboardFiles()) {
    System.out.println("Clipboard contains file list");
}

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API Reference

Text Operations

• setClipboardText(String text) — Copy text to clipboard
• getClipboardText() — Get text from clipboard
• hasClipboardText() — Check if clipboard contains text
• clearClipboard() — Clear clipboard contents

Image Operations

• setClipboardImage(int width, int height, int[] pixels) — Copy RGBA image to clipboard (DIB format)
• getClipboardImage() — Get image from clipboard (returns [width, height, pixelData...])
• hasClipboardImage() — Check if clipboard contains image

File List Operations

• setClipboardFiles(String[] filePaths) — Copy file list to clipboard (CF_HDROP format)
• getClipboardFiles() — Get file list from clipboard
• hasClipboardFiles() — Check if clipboard contains file list

Clipboard Info

• isFormatAvailable(int format) — Check if format is available
• getFormatCount() — Get number of available formats

Format Constants

• CF_TEXT = 1 — ANSI text
• CF_UNICODETEXT = 13 — Unicode text (UTF-16)
• CF_BITMAP = 2 — Bitmap image
• CF_DIB = 8 — Device Independent Bitmap
• CF_HDROP = 15 — File list

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Build from Source

Prerequisites

1. Java Development Kit (JDK) 17 or higher

Download: https://www.oracle.com/java/technologies/downloads/ or https://adoptium.net/

Verify installation:

java -version
javac -version

2. Visual Studio 2019 or 2022 (Community Edition is free)

Download: https://visualstudio.microsoft.com/downloads/

Required components:

• ✅ Desktop development with C++ workload
• ✅ Windows 10/11 SDK
• ✅ MSVC v142/v143 - VS 2019/2022 C++ x64/x86 build tools

3. Apache Maven 3.8+ (optional, for packaging)

Download: https://maven.apache.org/download.cgi

Build

git clone https://github.com/andrestubbe/fastclipboard.git
cd fastclipboard

# Compile native DLL
compile.bat

# Build Java + package
mvn clean package

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Platform Support

Platform	Version	Status
Windows 11	v1.0	✅ Full support (Win32 API)
Windows 10	v1.0	✅ Full support (Win32 API)
Linux	—	❌ Not planned
macOS	—	❌ Not planned

Windows-only by design — we focus on maximum performance on the most common platform.

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Use Cases

• Automation scripts — reliable clipboard operations
• Data processing pipelines — fast text transfer
• Bot development — stable clipboard interaction
• Test automation — consistent clipboard behavior
• Desktop applications — bug-free clipboard access

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License

MIT License — free for commercial and private use. See LICENSE for details.

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Related Projects

• FastHotkey - Ultra-fast global hotkey library
• FastRobot - High-performance screen capture
• FastGraphics - GPU-accelerated graphics
• FastTheme - OS-aware Display/Theme monitor

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Support the Project

If FastClipboard helps you build something awesome:

• Star the repository ⭐
• Share with other developers
• Report issues and suggest features
• Contribute improvements via pull requests

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Small package. Maximum speed. Zero bloat. 🚀📋

Replace buggy Java clipboard with stable native performance!