Package org.jfree.report.util
Class WeakReferenceList
java.lang.Object
org.jfree.report.util.WeakReferenceList
- All Implemented Interfaces:
Serializable
,Cloneable
The WeakReference list uses
java.lang.ref.WeakReference
s to store its
contents. In contrast to the WeakHashtable, this list knows how to restore missing
content, so that garbage collected elements can be restored when they are accessed.
By default this list can contain 25 elements, where the first element is stored using a
strong reference, which is not garbage collected.
Restoring the elements is not implemented, concrete implementations will have to
override the restoreChild(int)
method. The getMaxChildCount
method defines the maxmimum number of children in the list. When more than
maxChildCount
elements are contained in this list, add will always return
false to indicate that adding the element failed.
To customize the list, override createReference to create a different kind of
reference.
This list is able to add or clearFromParent elements, but inserting or removing of elements is
not possible.
- Author:
- Thomas Morgner
- See Also:
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Constructor Summary
ConstructorsModifierConstructorDescriptionprotected
WeakReferenceList
(int maxChildCount) Creates a new weak reference list. -
Method Summary
Modifier and TypeMethodDescriptionboolean
Adds the element to the list.protected Object
clone()
Creates and returns a copy of this object.get
(int index) Returns the child stored at the given index.protected int
getChildPos
(int index) Returns the internal storage position for the child.protected Object
Returns the master element of this list.protected final int
Returns the maximum number of children in this list.int
getSize()
Returns the size of the list.protected boolean
isMaster
(int index) Returns true, if the given index denotes a master index of this list.protected abstract Object
restoreChild
(int index) Attempts to restore the child stored on the given index.void
Replaces the child stored at the given index with the new child which can be null.
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Constructor Details
-
WeakReferenceList
protected WeakReferenceList(int maxChildCount) Creates a new weak reference list. The storage of the list is limited to getMaxChildCount() elements.- Parameters:
maxChildCount
- the maximum number of elements.
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Method Details
-
getMaxChildCount
protected final int getMaxChildCount()Returns the maximum number of children in this list.- Returns:
- the maximum number of elements in this list.
-
getMaster
Returns the master element of this list. The master element is the element stored by a strong reference and cannot be garbage collected.- Returns:
- the master element
-
restoreChild
Attempts to restore the child stored on the given index.- Parameters:
index
- the index.- Returns:
- null if the child could not be restored or the restored child.
-
get
Returns the child stored at the given index. If the child has been garbage collected, it gets restored using the restoreChild function.- Parameters:
index
- the index.- Returns:
- the object.
-
set
Replaces the child stored at the given index with the new child which can be null.- Parameters:
report
- the object.index
- the index.
-
add
Adds the element to the list. If the maximum size of the list is exceeded, this function returns false to indicate that adding failed.- Parameters:
rs
- the object.- Returns:
- true, if the object was successfully added to the list, false otherwise
-
isMaster
protected boolean isMaster(int index) Returns true, if the given index denotes a master index of this list.- Parameters:
index
- the index.- Returns:
- true if the index is a master index.
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getChildPos
protected int getChildPos(int index) Returns the internal storage position for the child.- Parameters:
index
- the index.- Returns:
- the internal storage index.
-
getSize
public int getSize()Returns the size of the list.- Returns:
- the size.
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clone
Creates and returns a copy of this object. The precise meaning of "copy" may depend on the class of the object. The general intent is that, for any object x, the expression:x.clone() != x
x.clone().getClass() == x.getClass()
x.clone().equals(x)
- Overrides:
clone
in classObject
- Returns:
- a clone of this instance.
- Throws:
CloneNotSupportedException
- if the object's class does not support theCloneable
interface. Subclasses that override theclone
method can also throw this exception to indicate that an instance cannot be cloned.- See Also:
-