Metronome

java.lang.Object
- event.Metronome

All Implemented Interfaces:

java.lang.Runnable

Direct Known Subclasses:

UDPDrivenMetronome
```
public class Metronome
extends java.lang.Object
implements java.lang.Runnable
```
A Metronome "ticks" at regular intervals, informing any registered listeners

We use a Metronome instead of a java.util.Timer or a javax.swing.Timer object for two reasons:
1. It is more generic (i.e., the micro edition of Java does not have a javax.swing.Timer)
2. It is instructive with regard to multi-threading, the observer pattern, the Java event-dispatch thread, and inner classes.
3. It gives us the option of using both fixed-delay and fixed-rate execution.
The biggest disadvantage of this class is that it does not use thread sharing. Hence, an application should not use many different Metronome objects.

A Metronome may "drift" since the sleep() method is not guaranteed to return in exactly the right amount of time. A "fixed rate" metronome will attempt to fix this (by notifying listeners in quick succession).

The time that is reported to listeners will depend on the operating mode. A "fixed interval" Metronome will report the time as if it is drift-free. That is, the difference in reported times will be exactly the delay (even when the Metronome has drifted). A "fixed rate" Metronome will report the time as if it is correcting the drift. That is, the different in reported times will reflect the amount of time it tried to wait between reports. Neither will report the actual time between reports. A listener that wants to know this information must use System.currentTimeMillis() itself.
Version:

1.0

Author:

Prof. David Bernstein, James Madison University

See Also:

"The Design and Implementation of Multimedia Software © 2011"

Constructor Summary

Constructors
Constructor and Description
`Metronome()` Default Constructor.
`Metronome(int delay)` Explicit Value Constructor.
`Metronome(int delay, boolean adjusting)` Explicit Value Constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addListener(MetronomeListener ml)` Add a MetronomeListener.
`int`	`getDelay()` Get the current delay.
`int`	`getNumberOfListeners()` Get the number of listeners.
`void`	`removeListener(MetronomeListener ml)` Remove a MetronomeListener.
`void`	`reset()` Reset the time Note: This method should only be called when the Metronome is not running.
`void`	`run()` The code that is executed in the timer thread (required by Runnable).
`void`	`setMultiplier(int multiplier)` Set the multiplier (i.e., the apparent speed-up factor).
`void`	`setTime(int time)` Set the current time.
`void`	`start()` Start this Metronome.
`void`	`stop()` Stop this Metronome "immediately".

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Metronome
```
public Metronome()
```
    Default Constructor.
  - Metronome
```
public Metronome(int delay)
```
    Explicit Value Constructor.
    Constructs a "fixed interval" Metronome with the given delay
    
    Parameters:
    
    delay - The number of milliseconds between ticks
  - Metronome
```
public Metronome(int delay,
                 boolean adjusting)
```
    Explicit Value Constructor.
    
    Parameters:
    
    delay - The number of milliseconds between ticks
    
    adjusting - true for "fixed rate"; false for "fixed interval"
- Method Detail
  - addListener
```
public void addListener(MetronomeListener ml)
```
    Add a MetronomeListener.
    
    Parameters:
    
    ml - The MetronomeListener to add
  - getDelay
```
public int getDelay()
```
    Get the current delay.
    
    Returns:
    
    The current delay
  - getNumberOfListeners
```
public int getNumberOfListeners()
```
    Get the number of listeners.
    
    Returns:
    
    The number of listeners
  - removeListener
```
public void removeListener(MetronomeListener ml)
```
    Remove a MetronomeListener.
    
    Parameters:
    
    ml - The MetronomeListener to remove
  - reset
```
public void reset()
```
    Reset the time Note: This method should only be called when the Metronome is not running.
  - run
```
public void run()
```
    The code that is executed in the timer thread (required by Runnable).
    
    Specified by:
    
    run in interface java.lang.Runnable
  - setMultiplier
```
public void setMultiplier(int multiplier)
```
    Set the multiplier (i.e., the apparent speed-up factor).
    Note: This method should only be called when the Metronome is not running
    
    Parameters:
    
    multiplier - The multiplier
  - setTime
```
public void setTime(int time)
```
    Set the current time.
    Note: This method should only be called when the Metronome is not running
    
    Parameters:
    
    time - The current time
  - start
```
public void start()
```
    Start this Metronome.
  - stop
```
public void stop()
```
    Stop this Metronome "immediately".

Class Metronome

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Metronome

Metronome

Metronome

Method Detail

addListener

getDelay

getNumberOfListeners

removeListener

reset

run

setMultiplier

setTime

start

stop