java - GLFW with LWJGL - glfwGetKey once -

i'm developing game java , lwjgl3. don't understand how fix problem, i've tried search on internet information lwjgl minimal , couldn't find glfw.

let's example have menu 4 buttons (new game, options, credits, exit) , count variable know 1 selected. every time arrow key pressed want subtract 1 select, select previous one, , same down arrow key, want add one.

the problem following: if in frame 0 press arrow key count variable added in next frame key still pressed, added again. don't know how fix this, tried changing glfw_press glfw_release, want action happen when key pressed.

if ((glfwgetkey(window, glfw_key_up) == glfw_repeat) && select > 0) {     button[select].toggleselect();     select--;     button[select].toggleselect(); }  if ((glfwgetkey(window, glfw_key_down) == glfw_repeat) && select < button.length) {     button[select].toggleselect();     select++;     button[select].toggleselect(); } 

i know code can throw array index out of bounds exception

you should register key callback:

private glfwkeycallback keycallback;  // ...  keycallback = new glfwkeycallback() {     @override     public void invoke(long window, int key, int scancode, int action, int mods) {         if (action == glfw_press) {             if (key == glfw_key_up && /*...*/) {                 // ...             }             if (key == glfw_key_down && /*...*/) {                 // ...             }         }     } } glfwsetkeycallback(window, keycallback); 

the invoke() method called every time key event generated. action parameter can take 3 values:

• glfw_press when key pressed
• glfw_repeat afterwards, when key still being pressed
• glfw_release when key wast released

while glfwgetkey() returns glfw_press or glfw_release, key callback uses glfw_press first time key being pressed , glfw_repeat afterwards, allowing differentiate between first frame during key pressed , subsequent ones.