Package ev3dev.sensors

Class Button

java.lang.Object

ev3dev.sensors.Button

public class Button
extends java.lang.Object

Abstraction for an NXT/EV3 button. Example:

 EV3Key.ENTER.waitForPressAndRelease();
 Sound.playTone(1000, 1);
 

Notions: The API is designed around two notions: states (up / down) and events (press / release). It is said that a button is pressed (press event), if its state changes from up to down. Similarly, it is said that a button is released (release event), if its states changed from down to up. Thread Safety: All methods that return buttons states can be used safely from multiple threads, even while a call to one of the waitFor* methods active. However, it is not safe to invoke waitFor* methods in parallel from different threads. This includes the waitFor* methods of different buttons. For example EV3Key.ENTER.waitForPress() must not be invoked in parallel to EV3Key.ESCAPE.waitForPress() or the static EV3Key.waitForAnyEvent(). In case this is needed, it is strongly recommended that you write your own Thread, which waits for button events and dispatches the events to anyone who's interested.

Field Summary

Fields

Modifier and Type	Field and Description
private static Key	ALL
static Key	DOWN The Down button.
static Key	ENTER The Enter button.
static Key	ESCAPE The Escape button.
static Key	LEFT The Left button.
private static Logger	log
static Key	RIGHT The Right button.
static Key	UP The Up button.

Constructor Summary

Constructors

Constructor and Description
Button()

Method Summary

Modifier and Type	Method and Description
static int	waitForAnyEvent() Waits for some button to be pressed or released.
static int	waitForAnyEvent(int timeout) Waits for some button to be pressed or released.
static int	waitForAnyPress() Waits for some button to be pressed.
static int	waitForAnyPress(int timeout) Waits for some button to be pressed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

log

private static final Logger log

ENTER

public static final Key ENTER

The Enter button.

LEFT

public static final Key LEFT

The Left button.

RIGHT

public static final Key RIGHT

The Right button.

ESCAPE

public static final Key ESCAPE

The Escape button.

UP

public static final Key UP

The Up button.

DOWN

public static final Key DOWN

The Down button.

ALL

private static final Key ALL

Constructor Detail

Button

public Button()

Method Detail

waitForAnyEvent

public static int waitForAnyEvent()

Waits for some button to be pressed or released. Which buttons have been released or pressed is returned as a bitmask. The lower eight bits (bits 0 to 7) indicate, which buttons have been pressed. Bits 8 to 15 indicate which buttons have been released.

Returns:

the bitmask

waitForAnyEvent

public static int waitForAnyEvent(int timeout)

Waits for some button to be pressed or released. Which buttons have been released or pressed is returned as a bitmask. The lower eight bits (bits 0 to 7) indicate, which buttons have been pressed. Bits 8 to 15 indicate which buttons have been released.

Parameters:

timeout - The maximum number of milliseconds to wait

Returns:

the bitmask

waitForAnyPress

public static int waitForAnyPress(int timeout)

Waits for some button to be pressed. If a button is already pressed, it must be released and pressed again.

Parameters:

timeout - The maximum number of milliseconds to wait

Returns:

the ID of the button that has been pressed or in rare cases a bitmask of button IDs, 0 if the given timeout is reached

waitForAnyPress

public static int waitForAnyPress()

Waits for some button to be pressed. If a button is already pressed, it must be released and pressed again.

Returns:

the ID of the button that has been pressed or in rare cases a bitmask of button IDs