SpinnerModel for sequences of numbers.
The upper and lower bounds of the sequence are defined
by properties called minimum and
maximum. The size of the increase or decrease
computed by the nextValue and
previousValue methods is defined by a property called
stepSize. The minimum and
maximum properties can be null
to indicate that the sequence has no lower or upper limit.
All of the properties in this class are defined in terms of two
generic types: Number and
Comparable, so that all Java numeric types
may be accommodated. Internally, there's only support for
values whose type is one of the primitive Number types:
Double, Float, Long,
Integer, Short, or Byte.
To create a SpinnerNumberModel for the integer
range zero to one hundred, with
fifty as the initial value, one could write:
Integer value = new Integer(50); Integer min = new Integer(0); Integer max = new Integer(100); Integer step = new Integer(1); SpinnerNumberModel model = new SpinnerNumberModel(value, min, max, step); int fifty = model.getNumber().intValue();
Spinners for integers and doubles are common, so special constructors for these cases are provided. For example to create the model in the previous example, one could also write:
SpinnerNumberModel model = new SpinnerNumberModel(50, 0, 100, 1);
This model inherits a ChangeListener.
The ChangeListeners are notified
whenever the model's value, stepSize,
minimum, or maximum properties changes.
SpinnerModel that represents
a closed sequence of
numbers from minimum to maximum. The
nextValue and previousValue methods
compute elements of the sequence by adding or subtracting
stepSize respectively. All of the parameters
must be mutually Comparable, value
and stepSize must be instances of Integer
Long, Float, or Double.
The minimum and maximum parameters
can be null to indicate that the range doesn't
have an upper or lower bound.
If value or stepSize is null,
or if both minimum and maximum
are specified and mininum > maximum then an
IllegalArgumentException is thrown.
Similarly if (minimum <= value <= maximum) is false,
an IllegalArgumentException is thrown.
SpinnerNumberModel with the specified
value, minimum/maximum bounds,
and stepSize.SpinnerNumberModel with the specified
value, minimum/maximum bounds,
and stepSize.SpinnerNumberModel with no
minimum or maximum value,
stepSize equal to one, and an initial value of zero.
The equals method implements an equivalence relation
on non-null object references:
x, x.equals(x) should return
true.
x and y, x.equals(y)
should return true if and only if
y.equals(x) returns true.
x, y, and z, if
x.equals(y) returns true and
y.equals(z) returns true, then
x.equals(z) should return true.
x and y, multiple invocations of
x.equals(y) consistently return true
or consistently return false, provided no
information used in equals comparisons on the
objects is modified.
x,
x.equals(null) should return false.
The equals method for class Object implements
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values x and
y, this method returns true if and only
if x and y refer to the same object
(x == y has the value true).
Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.
ChangeListeners added
to this AbstractSpinnerModel with addChangeListener().myAbstractSpinnerModel.getListeners(ChangeListener.class);
getNextValue
and getPreviousValue methods.java.util.Hashtable.
The general contract of hashCode is:
hashCode method on each of
the two objects must produce the same integer result.
As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
wait methods.
The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object. The awakened thread will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner of this object's monitor. A thread becomes the owner of the object's monitor in one of three ways:
synchronized statement
that synchronizes on the object.
Class, by executing a
synchronized static method of that class.
Only one thread at a time can own an object's monitor.
wait methods.
The awakened threads will not be able to proceed until the current thread relinquishes the lock on this object. The awakened threads will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened threads enjoy no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
maximum is null, then there
is no upper bound. No bounds checking is done here; the new
maximum value may invalidate the
(minimum <= value < maximum)
invariant enforced by the constructors. This is to simplify updating
the model, naturally one should ensure that the invariant is true
before calling the next, previous,
or setValue methods.
Typically this property is a Number of the same type
as the value however it's possible to use any
Comparable with a compareTo
method for a Number with the same type as the value.
See
setMinimum for an example.
This method fires a ChangeEvent if the
maximum has changed.
minimum is null,
then there is no lower bound. No bounds checking is done here;
the new minimum value may invalidate the
(minimum <= value <= maximum)
invariant enforced by the constructors. This is to simplify updating
the model, naturally one should ensure that the invariant is true
before calling the getNextValue,
getPreviousValue, or setValue methods.
Typically this property is a Number of the same type
as the value however it's possible to use any
Comparable with a compareTo
method for a Number with the same type as the value.
For example if value was a Long,
minimum might be a Date subclass defined like this:
MyDate extends Date { // Date already implements Comparable
public int compareTo(Long o) {
long t = getTime();
return (t < o.longValue() ? -1 : (t == o.longValue() ? 0 : 1));
}
}
This method fires a ChangeEvent
if the minimum has changed.
getNextValue and getPreviousValue
methods. An IllegalArgumentException
is thrown if stepSize is null.
This method fires a ChangeEvent if the
stepSize has changed.
value is
null, or not a Number, an
IllegalArgumentException is thrown. No
bounds checking is done here; the new value may invalidate the
(minimum <= value <= maximum)
invariant enforced by the constructors. It's also possible to set
the value to be something that wouldn't naturally occur in the sequence,
i.e. a value that's not modulo the stepSize.
This is to simplify updating the model, and to accommodate
spinners that don't want to restrict values that have been
directly entered by the user. Naturally, one should ensure that the
(minimum <= value <= maximum) invariant is true
before calling the next, previous, or
setValue methods.
This method fires a ChangeEvent if the value has changed.
toString method returns a string that
"textually represents" this object. The result should
be a concise but informative representation that is easy for a
person to read.
It is recommended that all subclasses override this method.
The toString method for class Object
returns a string consisting of the name of the class of which the
object is an instance, the at-sign character `@', and
the unsigned hexadecimal representation of the hash code of the
object. In other words, this method returns a string equal to the
value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())
The current thread must own this object's monitor. The thread
releases ownership of this monitor and waits until another thread
notifies threads waiting on this object's monitor to wake up
either through a call to the notify method or the
notifyAll method. The thread then waits until it can
re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait();
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.The current thread must own this object's monitor.
This method causes the current thread (call it T) to place itself in the wait set for this object and then to relinquish any and all synchronization claims on this object. Thread T becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:
A thread can also wake up without being notified, interrupted, or timing out, a so-called spurious wakeup. While this will rarely occur in practice, applications must guard against it by testing for the condition that should have caused the thread to be awakened, and continuing to wait if the condition is not satisfied. In other words, waits should always occur in loops, like this one:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout);
... // Perform action appropriate to condition
}
(For more information on this topic, see Section 3.2.3 in Doug Lea's
"Concurrent Programming in Java (Second Edition)" (Addison-Wesley,
2000), or Item 50 in Joshua Bloch's "Effective Java Programming
Language Guide" (Addison-Wesley, 2001).
If the current thread is interrupted by another thread while it is waiting, then an InterruptedException is thrown. This exception is not thrown until the lock status of this object has been restored as described above.
Note that the wait method, as it places the current thread into the wait set for this object, unlocks only this object; any other objects on which the current thread may be synchronized remain locked while the thread waits.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
This method is similar to the wait method of one
argument, but it allows finer control over the amount of time to
wait for a notification before giving up. The amount of real time,
measured in nanoseconds, is given by:
1000000*timeout+nanos
In all other respects, this method does the same thing as the method of one argument. In particular, wait(0, 0) means the same thing as wait(0).
The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until either of the following two conditions has occurred:
notify method
or the notifyAll method.
timeout
milliseconds plus nanos nanoseconds arguments, has
elapsed.
The thread then waits until it can re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout, nanos);
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.