org.incava.diff

Class Differ<ObjectType,DiffType extends Difference>

java.lang.Object

org.incava.diff.Differ<ObjectType,DiffType>

Direct Known Subclasses:

Diff

public abstract class Differ<ObjectType,DiffType extends Difference>
extends java.lang.Object

Compares two collections, returning a list of the additions, changes, and deletions between them. A Comparator may be passed as an argument to the constructor, and will thus be used. If not provided, the initial value in the from collection will be looked at to see if it supports the Comparable interface. If so, its equals and compareTo methods will be invoked on the instances in the "from" and "to" collections; otherwise, for speed, hash codes from the objects will be used instead for comparison.

The file FileDiff.java shows an example usage of this class, in an application similar to the Unix "diff" program.

Constructor Summary

Constructors

Constructor and Description
Differ(java.util.List<ObjectType> from, java.util.List<ObjectType> to) Constructs the Differ object for the two collections, using the default comparison mechanism between the objects, such as equals and compareTo.
Differ(java.util.List<ObjectType> from, java.util.List<ObjectType> to, java.util.Comparator<ObjectType> comp) Constructs the Differ object for the two collections, using the given comparator.
Differ(ObjectType[] from, ObjectType[] to) Constructs the Differ object for the two arrays, using the default comparison mechanism between the objects, such as equals and compareTo.
Differ(ObjectType[] from, ObjectType[] to, java.util.Comparator<ObjectType> comp) Constructs the Differ object for the two arrays, using the given comparator.

Method Summary

Modifier and Type	Method and Description
protected void	addPending() Adds the last difference, if pending.
abstract DiffType	createDifference(java.lang.Integer delStart, java.lang.Integer delEnd, java.lang.Integer addStart, java.lang.Integer addEnd) Subclasses implement this to return their own subclass of Difference.
java.util.List<DiffType>	diff() Deprecated. execute is a more accurate and descriptive name.
java.util.List<DiffType>	execute() Runs diff and returns the results.
protected void	onFromNotTo(int fromIdx, int toIdx) Invoked for elements in from and not in to.
protected void	onMatch(int fromIdx, int toIdx) Invoked for elements matching in from and to.
protected void	onToNotFrom(int fromIdx, int toIdx) Invoked for elements in to and not in from.
protected void	traverseEndOfSequences(int fromIdx, int toIdx)
protected void	traverseSequences() Traverses the sequences, seeking the longest common subsequences, invoking the methods finishedFrom, finishedTo, onFromNotTo, and onToNotFrom.

Methods inherited from class java.lang.Object

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

Constructor Detail

Differ

public Differ(ObjectType[] from,
              ObjectType[] to,
              java.util.Comparator<ObjectType> comp)

Constructs the Differ object for the two arrays, using the given comparator.

Differ

public Differ(ObjectType[] from,
              ObjectType[] to)

Constructs the Differ object for the two arrays, using the default comparison mechanism between the objects, such as equals and compareTo.

Differ

public Differ(java.util.List<ObjectType> from,
              java.util.List<ObjectType> to)

Constructs the Differ object for the two collections, using the default comparison mechanism between the objects, such as equals and compareTo.

Differ

public Differ(java.util.List<ObjectType> from,
              java.util.List<ObjectType> to,
              java.util.Comparator<ObjectType> comp)

Constructs the Differ object for the two collections, using the given comparator.

Method Detail

execute

public java.util.List<DiffType> execute()

Runs diff and returns the results.

diff

@Deprecated
public java.util.List<DiffType> diff()

Deprecated. execute is a more accurate and descriptive name.

Runs diff and returns the results.

createDifference

public abstract DiffType createDifference(java.lang.Integer delStart,
                                          java.lang.Integer delEnd,
                                          java.lang.Integer addStart,
                                          java.lang.Integer addEnd)

Subclasses implement this to return their own subclass of Difference.

addPending

protected void addPending()

Adds the last difference, if pending.

traverseSequences

protected void traverseSequences()

Traverses the sequences, seeking the longest common subsequences, invoking the methods finishedFrom, finishedTo, onFromNotTo, and onToNotFrom.

traverseEndOfSequences

protected void traverseEndOfSequences(int fromIdx,
                                      int toIdx)

onFromNotTo

protected void onFromNotTo(int fromIdx,
                           int toIdx)

Invoked for elements in from and not in to.

onToNotFrom

protected void onToNotFrom(int fromIdx,
                           int toIdx)

Invoked for elements in to and not in from.

onMatch

protected void onMatch(int fromIdx,
                       int toIdx)

Invoked for elements matching in from and to.