[ozrien]

If you are using RobotBuilder then you can to a "whenPressed" action...
https://wpilib.screenstepslive.com/s...e-to-a-command

If you are using command classes yourself there is a Button class you could wire into the scheduler.

If you are just writing straight java, I usually just copy/paste the following...

//instance variables
    boolean [] btns  = new boolean [] {false,false,false,false,false};
    boolean [] last  = new boolean [] {false,false,false,false,false};

//get latest
    public void teleopPeriodic() {

        btns[1] = _joy.getRawButton(1);
    	btns[2] = _joy.getRawButton(2);
    	btns[3] = _joy.getRawButton(3);
    	btns[4] = _joy.getRawButton(4);

    	if(!last[3] && btns[3]){
    		//btn3 just pressed, do something
    	}

// bottom of teleop save all btns into last
		for(i=0;i<last.length;++i)
			last[i] = btns[i];