8362637: Convert java.nio.ByteOrder to an enum

[RogerRiggs]

Convert java.nio.ByteOrder to an enum.
The class declaration is changed from public class to public enum.
Enums are Comparable so declare LITTLE_ENDIAN before BIG_ENDIAN so LITTLE_ENDIAN is less than BIG_ENDIAN.
The implementation is simplified, removing the constructor and explicit static fields.
Remove the override of toString; the javadoc provided by Enum is sufficient.

No changes to other classes or implementations are needed to pass Tier 1-3.

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change requires CSR request JDK-8369130 to be approved

Issues

• JDK-8362637: Convert java.nio.ByteOrder to an enum (Enhancement - P4)
• JDK-8369130: Convert java.nio.ByteOrder to an enum (CSR)

Reviewers

• Alan Bateman (@AlanBateman - Reviewer)
• Chen Liang (@liach - Reviewer)
• Brian Burkhalter (@bplb - Reviewer)

Reviewing

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[bridgekeeper]

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[openjdk]

@RogerRiggs This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8362637: Convert java.nio.ByteOrder to an enum

Reviewed-by: alanb, liach, bpb

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At the time when this comment was updated there had been 182 new commits pushed to the master branch:

• 4ed3640: 8369251: Opensource few tests
• a7a3a66: 8354469: Keytool exposes the password in plain text when command is piped using | grep
• c9cbd31: 8307495: Specialize atomic bitset functions for aix-ppc
• ... and 179 more: https://git.openjdk.org/jdk/compare/5fccabff15ae8bcc3d03156fa331bbc0fefb0cbe...master

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (86ddbfee)

[liach]

Why do we reorder the BIG_ENDIAN and LITTLE_ENDIAN fields?

[AlanBateman]

Why do we reorder the BIG_ENDIAN and LITTLE_ENDIAN fields?

enums are Comparable and giving LITTLE_ENDIAN the 0 ordinal means it is less than BIG_ENDIAN. I don't think byte orders will be compared too often but it does avoid a surprise.

[liach]

Thanks for this interesting interpretation, Alan. Looks good. Some bikeshedding attached.

[liach]

Suggested change

	public enum ByteOrder {
	public enum ByteOrder {

[liach]

Suggested change

	LITTLE_ENDIAN,
	/**
	LITTLE_ENDIAN,
	/**

[bplb]

Looks good to me as well.

[wenshao]

getIntB/getIntL/putIntB/putIntL/getLongB/getLongL/putLongL/getLongL If the optimizer can handle it, these methods should be provided in ByteOrder

[liach]

I think we will do that later. A lot of these operations are used in early bootstrap when we don't want to set up everything enums use.

[RogerRiggs]

ByteOrder is just an enum, the get and set methods suggested belong elsewhere. The optimizer can do the right thing relative to the enum regardless of where they are implemented.

[RogerRiggs]

/integrate

[openjdk]

Going to push as commit 95380e1.
Since your change was applied there have been 200 commits pushed to the master branch:

• 87092ef: 8183336: Better cleanup for jdk/test/java/lang/module/customfs/ModulesInCustomFileSystem.java
• 303eb10: 8369573: Add missing compile commands help documentation for the signature part of method patterns
• f2a9983: 8369804: TestGenerators.java fails with IllegalArgumentException: bound must be greater than origin
• ... and 197 more: https://git.openjdk.org/jdk/compare/5fccabff15ae8bcc3d03156fa331bbc0fefb0cbe...master

Your commit was automatically rebased without conflicts.

[openjdk]

@RogerRiggs Pushed as commit 95380e1.

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