java.lang.NoClassDefFoundError in LWJGL when attempting to run in Eclipse
<p>So I'm a moderately novice programmer, but after toiling over this error for a while, I can't find a solution. I'm making a puzzle game, and for some reason, it just refuses to run now. I always get this error:</p>

<pre><code>Exception in thread "main" java.lang.NoClassDefFoundError: Could not initialize class org.lwjgl.system.Library
    at org.lwjgl.system.MemoryAccess.&lt;clinit&gt;(MemoryAccess.java:22)
    at org.lwjgl.system.Pointer.&lt;clinit&gt;(Pointer.java:24)
    at org.lwjgl.glfw.GLFW.&lt;clinit&gt;(GLFW.java:594)
    at Graphics.LaunchWindow.run(LaunchWindow.java:32)
    at Graphics.LaunchWindow.main(LaunchWindow.java:96)
</code></pre>

<p>Eclipse tells me that none of my code has errors within it, and reinstalling LWJGL doesn't work (I tried both the stable 3.0.0b build 64 and the nightly 3.0.0 build 22). I have seen other similar questions taking about making sure the lwjgl.jar is in the class path, but I've made sure multiple times. Also, if it matters, I have lwjgl_util.jar and slick_util.jar in the class path as well, and even though they are outdated compared to lwjgl 3, removing them from the class path makes no difference.</p>

<pre><code>package Graphics;

import org.lwjgl.glfw.*;
import org.lwjgl.opengl.*;

import Controls.KeyParser;
import Controls.KeyboardInput;

import static org.lwjgl.glfw.GLFW.*;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.system.MemoryUtil.*;

public class LaunchWindow {

private GLFWErrorCallback errorCallback;
private GLFWKeyCallback   keyCallback;

public int width = 1024;
public int height = 600;
public String title = "Duplicity";
public long fullscreen = NULL;
public long window;

public void run() {

    try {
        init();
        loop();
        glfwDestroyWindow(window);
        keyCallback.release();
    } finally {
        glfwTerminate();
        errorCallback.release();
    }
}

private void init() {

    glfwSetErrorCallback(errorCallback = GLFWErrorCallback.createPrint(System.err));

    KeyboardInput.initiate();

    if ( glfwInit() != GLFW_TRUE )
        throw new IllegalStateException("Unable to initialize GLFW");

    if(fullscreen == NULL){
        glfwDefaultWindowHints();
        glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
        glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE);
    }

    window = glfwCreateWindow(width, height, title, fullscreen, NULL);
    if (window == NULL)
        throw new RuntimeException("Failed to create the GLFW window");

    glfwSetKeyCallback(window, keyCallback = new GLFWKeyCallback() {
        @Override
        public void invoke(long window, int key, int scancode, int action, int mods) {
            if ( key == GLFW_KEY_ESCAPE &amp;&amp; action == GLFW_RELEASE )
                glfwSetWindowShouldClose(window, GLFW_TRUE);
        }
    });

    GLFWVidMode vidmode = glfwGetVideoMode(glfwGetPrimaryMonitor());
    glfwSetWindowPos(window, (vidmode.width() - width) / 2, (vidmode.height() - height) / 2);
    glfwMakeContextCurrent(window);
    glfwSwapInterval(1);
    glfwShowWindow(window);

    keyCallback = GLFWKeyCallback.create(KeyboardInput::glfw_key_callback);
    keyCallback.set(window);

    /* mouseButtonCallback = GLFWMouseButtonCallback.create(Mouse::glfw_mouse_button_callback);
    mouseButtonCallback.set(window);

    cursorPosCallback = GLFWCursorPosCallback.create(Mouse::glfw_cursor_pos_callback);
    cursorPosCallback.set(window); */

    GL.createCapabilities();
}

public void loop() {

    GL.createCapabilities();
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

    while ( glfwWindowShouldClose(window) == GLFW_FALSE ) {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glfwSwapBuffers(window); 
        glfwPollEvents();
        new KeyParser().checkKeyState();
    }
}

public static void main(String[] args) {
    new LaunchWindow().run();
}
}
</code></pre>