Package com.itextpdf.pdfoptimizer.util

Class EqualityUtils

java.lang.Object
com.itextpdf.pdfoptimizer.util.EqualityUtils
public final class EqualityUtils extends Object
Class is used to perform comparison by content between two instances of PdfObject avoiding infinity recursions in case when the same indirect objects stores itself as a part of internal state.

Note that it is expected that compared objects are valid PdfObjects. It means that only indirect objects (PdfObject.isIndirect() is true) may be a reason of the recursion. Therefore certain checks done only for them. It can be possible to create a PdfObject manually for which equals / hashCode calculation will not work correctly.

  • Method Details

    • getHashCode

      public static int getHashCode (com.itextpdf.kernel.pdf.PdfObject object)
      Calculates a hash for the object. If Object.hashCode() is overridden for the class then it will be called. Otherwise custom calculation will be done.

      Two instances will have equal hashCode if they are considered as equal by areEqual(PdfObject, PdfObject) method.

      Note that checks to avoid infinity recursions are done only for indirect objects (PdfObject.isIndirect() is true).

      Parameters:
      object - is a PdfObject whose content-based hash code to compute
      Returns:
      a content-based hash code

    • areEqual

      public static boolean areEqual (com.itextpdf.kernel.pdf.PdfObject obj1, com.itextpdf.kernel.pdf.PdfObject obj2)
      Checks the equality of two object. If Object.equals(Object) ()} is overridden for the class then it will be called. Otherwise custom calculation will be done.

      If is possible that two objects cannot be compared because they are nested in each other or each into itself. In such case equality check for objects obj1 and obj2 may depend on the equality check for the same objects. To avoid infinity recursion in such cases equality check of nested objects will return true.

      For example if array A contains as its only element array B and array B contains as its only element array B then equals(A, B) will return true. It is because the first elements of each array are B and A respectively and during the whole process of comparison of A and B arrays any nested pair of A and B will be considered as equal. As the only elements of each array are considered as equal the result of equality check of two arrays will be true.

      However if array A contains array B and a PdfNumber 1 and array B contains array A and a PdfNumber 2 then will be considered as not equal. Equality check for the first elements of each array will return true as above but the second elements are different: 1 is not equal to 2. That is the reason why arrays A and B will be considered as not equal.

      Note that checks to avoid inifinity recursions are done only for indirect objects (PdfObject.isIndirect() is true).

      Parameters:
      obj1 - is the first PdfObject to compare
      obj2 - is the second PdfObject to compare
      Returns:
      true if objects are considered as equal