| java.lang.Object
 org.axiondb.util.ComparatorChain
| ComparatorChain | | public class ComparatorChain implements Comparator,Serializable(Code) | |
A ComparatorChain is a Comparator that wraps one or more Comparators in sequence. The
ComparatorChain calls each Comparator in sequence until either 1) any single Comparator
returns a non-zero result (and that result is then returned), or 2) the ComparatorChain
is exhausted (and zero is returned). This type of sorting is very similar to
multi-column sorting in SQL, and this class allows Java classes to emulate that kind of
behaviour when sorting a List.
To further facilitate SQL-like sorting, the order of any single Comparator in the list
can be reversed.
Calling a method that adds new Comparators or changes the ascend/descend sort after
compare(Object, Object) has been called will result in an
UnsupportedOperationException. However, take care to not alter the underlying
List of Comparators or the BitSet that defines the sort order.
Instances of ComparatorChain are not synchronized. The class is not thread-safe at
construction time, but it is thread-safe to perform multiple comparisons after
all the setup operations are complete.
author:
Morgan Delagrange
version:
$Revision: 1.1 $ $Date: 2005/10/13 02:25:32 $ |
| Method Summary | |
| public void | addComparator(Comparator comparator)
| | public void | addComparator(Comparator comparator, boolean reverse)
| | public int | compare(Object o1, Object o2)
Perform comparisons on the Objects as per Comparator.compare(o1,o2). | | public boolean | equals(Object that)
Returns true iff that Object is is a
Comparator whose ordering is known to be equivalent to mine.
This implementation returns true iff
that.
Object.getClass getClass() equals
this.getClass(), and the underlying comparators and order bits are
equal. | | public int | hashCode()
Implement a hash code for this comparator that is consistent with
ComparatorChain.equals . | | public boolean | isLocked()
Determine if modifications can still be made to the ComparatorChain. | | public void | setComparator(int index, Comparator comparator)
Replace the Comparator at the given index, maintaining the existing sort order. | | public void | setComparator(int index, Comparator comparator, boolean reverse)
| | public void | setForwardSort(int index)
Change the sort order at the given index in the ComparatorChain to a forward sort. | | public void | setReverseSort(int index)
Change the sort order at the given index in the ComparatorChain to a reverse sort. | | public int | size()
Number of Comparators in the current ComparatorChain. |
| comparatorChain | | protected List comparatorChain(Code) | | |
| isLocked | | protected boolean isLocked(Code) | | |
| ComparatorChain | | public ComparatorChain()(Code) | | Construct a ComparatorChain with no Comparators. You must add at least one
Comparator before calling the compare(Object,Object) method, or an
UnsupportedOperationException is thrown
|
| ComparatorChain | | public ComparatorChain(Comparator comparator)(Code) | | Construct a ComparatorChain with a single Comparator, sorting in the forward order
Parameters:
comparator - First comparator in the Comparator chain |
| ComparatorChain | | public ComparatorChain(Comparator comparator, boolean reverse)(Code) | | Construct a Comparator chain with a single Comparator, sorting in the given order
Parameters:
comparator - First Comparator in the ComparatorChain
Parameters:
reverse - false = forward sort; true = reverse sort |
| ComparatorChain | | public ComparatorChain(List list, BitSet bits)(Code) | | Construct a ComparatorChain from the Comparators in the given List. The sort order
of each column will be drawn from the given BitSet. When determining the sort order
for Comparator at index i in the List, the ComparatorChain will call
BitSet.get(i). If that method returns false, the forward sort
order is used; a return value of true indicates reverse sort order.
Parameters:
list - List of Comparators. NOTE: This constructor does not perform adefensive copy of the list
Parameters:
bits - Sort order for each Comparator. Extra bits are ignored, unless extraComparators are added by another method. |
| addComparator | | public void addComparator(Comparator comparator)(Code) | | Add a Comparator to the end of the chain using the forward sort order
Parameters:
comparator - Comparator with the forward sort order |
| addComparator | | public void addComparator(Comparator comparator, boolean reverse)(Code) | | Add a Comparator to the end of the chain using the given sort order
Parameters:
comparator - Comparator to add to the end of the chain
Parameters:
reverse - false = forward sort order; true = reverse sort order |
| equals | | public boolean equals(Object that)(Code) | | Returns true iff that Object is is a
Comparator whose ordering is known to be equivalent to mine.
This implementation returns true iff
that.
Object.getClass getClass() equals
this.getClass(), and the underlying comparators and order bits are
equal. Subclasses may want to override this behavior to remain consistent with the
Comparator.equals contract.
since:
Commons Collections 3.0 |
| hashCode | | public int hashCode()(Code) | | Implement a hash code for this comparator that is consistent with
ComparatorChain.equals .
since:
Commons Collections 3.0 |
| isLocked | | public boolean isLocked()(Code) | | Determine if modifications can still be made to the ComparatorChain.
ComparatorChains cannot be modified once they have performed a comparison.
true = ComparatorChain cannot be modified; false = ComparatorChain canstill be modified. |
| setComparator | | public void setComparator(int index, Comparator comparator) throws IndexOutOfBoundsException(Code) | | Replace the Comparator at the given index, maintaining the existing sort order.
Parameters:
index - index of the Comparator to replace
Parameters:
comparator - Comparator to place at the given index
exception:
IndexOutOfBoundsException - if index < 0 or index >= size() |
| setComparator | | public void setComparator(int index, Comparator comparator, boolean reverse)(Code) | | Replace the Comparator at the given index in the ComparatorChain, using the given
sort order
Parameters:
index - index of the Comparator to replace
Parameters:
comparator - Comparator to set
Parameters:
reverse - false = forward sort order; true = reverse sort order |
| setForwardSort | | public void setForwardSort(int index)(Code) | | Change the sort order at the given index in the ComparatorChain to a forward sort.
Parameters:
index - Index of the ComparatorChain |
| setReverseSort | | public void setReverseSort(int index)(Code) | | Change the sort order at the given index in the ComparatorChain to a reverse sort.
Parameters:
index - Index of the ComparatorChain |
| size | | public int size()(Code) | | Number of Comparators in the current ComparatorChain.
Comparator count |
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