Package org.apache.commons.text.diff

Class StringsComparator

java.lang.Object
org.apache.commons.text.diff.StringsComparator
public class StringsComparator
extends Object

It is guaranteed that the comparisons will always be done as o1.equals(o2) where o1 belongs to the first sequence and o2 belongs to the second sequence. This can be important if subclassing is used for some elements in the first sequence and the equals method is specialized.

Comparison can be seen from two points of view: either as giving the smallest modification allowing to transform the first sequence into the second one, or as giving the longest sequence which is a subsequence of both initial sequences. The equals method is used to compare objects, so any object can be put into sequences. Modifications include deleting, inserting or keeping one object, starting from the beginning of the first sequence.

This class implements the comparison algorithm, which is the very efficient algorithm from Eugene W. Myers An O(ND) Difference Algorithm and Its Variations. This algorithm produces the shortest possible edit script containing all the commands needed to transform the first sequence into the second one.

This code has been adapted from Apache Commons Collections 4.0.

Since:
1.0
See Also:
EditScript, EditCommand, CommandVisitor

  • Constructor Details

    • StringsComparator

      public StringsComparator​(String left, String right)
      Simple constructor.

      Creates a new instance of StringsComparator.

      It is guaranteed that the comparisons will always be done as o1.equals(o2) where o1 belongs to the first sequence and o2 belongs to the second sequence. This can be important if subclassing is used for some elements in the first sequence and the equals method is specialized.

      Parameters:
      left - first character sequence to be compared
      right - second character sequence to be compared

  • Method Details

    • getScript

      public EditScript<Character> getScript()
      Get the EditScript object.

      It is guaranteed that the objects embedded in the insert commands come from the second sequence and that the objects embedded in either the delete commands or keep commands come from the first sequence. This can be important if subclassing is used for some elements in the first sequence and the equals method is specialized.

      Returns:
      The edit script resulting from the comparison of the two sequences