Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-8257086

Clarify differences between {Float, Double}.equals and ==

    XMLWordPrintable

    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 16
    • Fix Version/s: 17
    • Component/s: core-libs
    • Labels:
      None
    • Subcomponent:
    • Resolved In Build:
      b08

      Description

      The equals methods on Float and Double are *not* just wrappers around the corresponding == operator because the IEEE 754 == operator does *not* define an equivalence relation. The properties of an equivalence relation are broken by NaN (since NaN is not equal to itself) and by -0.0/+0.0. While -0.0 and +0.0 compare as equal, they are distinct values that can change the value of a result of an operation; for example, +1.0/+0.0 is positive infinity while +1.0/-0.0 is negative infinity.

      This situation could be more clearly motivated than the oblique "This definition allows hash tables to operate properly." statement equals methods.

        Attachments

          Issue Links

            Activity

              People

              Assignee:
              darcy Joe Darcy
              Reporter:
              darcy Joe Darcy
              Votes:
              0 Vote for this issue
              Watchers:
              4 Start watching this issue

                Dates

                Created:
                Updated:
                Resolved: