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Java Style Guide: Remove obsolete information

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With the deprecation of Android M support, some things are now
irrelevant.

Bug: None
Change-Id: I55c4251a73dca01946deb6372346cdbdddb51abf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4135208
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Peter Conn <peconn@chromium.org>
Commit-Queue: Tommy Nyquist <nyquist@chromium.org>
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1092480}
This commit is contained in:
Andrew Grieve
2023-01-13 17:29:17 +00:00
committed by Chromium LUCI CQ
parent c576fff652
commit 8282bf2369
1 changed files with 19 additions and 21 deletions

40
styleguide/java/java.md

@ -15,7 +15,7 @@ get to decide.
[TOC]
## Java 10 language Features
## Java 10 Language Features
### Type deduction using `var`
@ -38,29 +38,27 @@ try (var ignored = StrictModeContext.allowDiskWrites()) {
```
## Java 8 Language Features
[Desugar](https://github.com/bazelbuild/bazel/blob/master/src/tools/android/java/com/google/devtools/build/android/desugar/Desugar.java)
is used to rewrite some Java 7 & 8 language constructs in a way that is
compatible with Java 6 (and thus all Android versions). Use of
[these features](https://developer.android.com/studio/write/java8-support)
is encouraged, but there are some gotchas:
[D8] is used to rewrite some Java 7 & 8 language constructs in a way that is
compatible with Java 6 (and thus all Android versions). Use of [these features]
is encouraged.
### Default Interface Methods
* Desugar makes default interface methods work by copy & pasting the default
implementations into all implementing classes.
* This technique is fine for infrequently-used interfaces, but should be
avoided (e.g. via a base class) if it noticeably increases method count.
[D8]: https://developer.android.com/studio/command-line/d8
[these features]: https://developer.android.com/studio/write/java8-support
### Lambdas and Method References
* These are syntactic sugar for creating anonymous inner classes.
* Use them only where the cost of an extra class & method definition is
justified.
## Java Library APIs
### try-with-resources
* Some library classes do not implement Closeable on older platform APIs.
Runtime exceptions are thrown if you use them with a try-with-resources.
Do not use the following classes in a try-with-resources:
* java.util.zip.ZipFile (implemented in API 19)
* java.net.Socket (implemented in API 19)
Android provides the ability to bundle copies of `java.` APIs alongside
application code, known as [Java Library Desugaring]. However, since this
bundling comes with a performance cost, Chrome does not use it. Treat `java.`
APIs the same as you would `android.` ones and guard them with
`Build.VERSION.SDK_INT` checks [when necessary]. The one exception is if the
method is [directly backported by D8] (these are okay to use, since they are
lightweight). Android Lint will fail if you try to use an API without a
corresponding `Build.VERSION.SDK_INT` guard or `@RequiresApi` annotation.
[Java Library Desugaring]: https://developer.android.com/studio/write/java8-support-table
[when necessary]: https://developer.android.com/reference/packages
[directly backported by D8]: https://source.chromium.org/chromium/chromium/src/+/main:third_party/r8/backported_methods.txt
## Other Language Features & APIs