public class Control implements InputProcessor {  

        public boolean key[] = new boolean[255];

        @Override  
        public boolean keyDown(int keycode) {  

            key[keycode] = true;  

            return true;  
        }  

        @Override  
        public boolean keyUp(int keycode) {  

            key[keycode] = false;  

            return true;  
        }  

        @Override  
        public boolean keyTyped(char character) {...}  

        @Override  
        public boolean touchDown(int screenX, int screenY, int pointer, int button) {...}  

        @Override  
        public boolean touchUp(int screenX, int screenY, int pointer, int button) {...}  

        @Override  
        public boolean touchDragged(int screenX, int screenY, int pointer) {...}  

        @Override  
        public boolean mouseMoved(int screenX, int screenY) {...}  

        @Override  
        public boolean scrolled(int amount) {...}  
}

Gdx.input.setInputProcessor(new Control());

public class Control implements InputProcessor {

       @Override
       public boolean keyDown(int keycode) {

           // Тут обрабатывается нажатие клавиши

           return true;
       }

       @Override
       public boolean keyUp(int keycode) {

           // Тут обрабатывается поднятие клавиши

           return true;
       }

       @Override
       public boolean keyTyped(char character) {...}

       @Override
       public boolean touchDown(int screenX, int screenY, int pointer, int button) {...}

       @Override
       public boolean touchUp(int screenX, int screenY, int pointer, int button) {...}

       @Override
       public boolean touchDragged(int screenX, int screenY, int pointer) {...}

       @Override
       public boolean mouseMoved(int screenX, int screenY) {...}

       @Override
       public boolean scrolled(int amount) {...}
}

boolean isDown;  
boolean executed;

public void render(float delta) {

         if (Gdx.input.isKeyPressed(Input.Keys.[ЛЮБАЯ КЛАВИША])) {
             isDown = true;
         } else {
             isDown = false;
             executed = false;
         }

         if (isDown && !executed) {
             // Обрабатываем нажатие клавиши

             executed = true;
         }

}

if(!Mouse.isInsideWindow() && Display.isActive()) { Mouse.setCursorPosition(Mouse.getX(), Mouse.getY()); }