Free Download External Annotations For Dependencies
Brigitte Bjork
For my task at work (resolving hardcoded String warnings) I want to not only share @NonNls annotations I add inside our project, but also the external annotations I add via "Add external annotation" in Android Studio in order for my coworkers to not be bombarded with useless warnings like I was starting at this project.
Disabling this type of annotation in general does not fix my problem as I want to keep seeing the useful warnings of this type.In addition, the usual functionality of selecting a folder somewhere in my file system to save the external annotions there in a tree-like structure is also not good enough, because my coworkers would still have to point Android Studio to this folder for every class/method they want to ignore a specific warning for.
When working with project code, you can type an annotation and then use the Annotate externally intention action. To access the intention actions menu, place the caret at an annotation and press Alt+Enter (or click the intention action icon).
Annotation-based null analysis is incomplete as long as libraries consumed by a project have no null annotations in their API. To fill this gap, it is now possible to attach "external annotations" to a library after the fact, i.e., without touching and re-packaging the library itself.
JDT now understands a new classpath attribute called "annotationpath", which - similar to attaching sources and javadoc - attaches a collection of external annotations to a particular classpath entry pointing to a library. The value of the new attribute can have any of these four shapes:
It is possible to consume external annotations when compiling outside the IDE or under the control of a build system like ant, maven or gradle. For this reason the batch compiler must be configured in situations where no Eclipse project is available as the context for compilation.
On the one hand, the file format could remain a private implementation detail of the compiler, if the IDE just provides the necessary operations for manipulating external annotations (like, e.g., quick assists). This would make the binary .class file format a natural choice for implementation, as it allows to store all required information and can already be interpreted by the compiler.
This basically means, that after any of the tokens L, T, [, +, -, * an optional "0" or "1" can occur, where "0" represents the nullable annotation, and "1" represents the nonnull annotation. Thus this format is independent of the concrete configured annotations to be used by the JDT compiler, and thus will not create a conflict, when external annotations are contributed from different sources.
Note that in this format, nullness of an array dimension follows the corresponding "[" token, whereas in Java source syntax it precedes that token, i.e., "@NonNull String @NonNull[] @Nullable[]" translated to "[1[0L1java/lang/String;". Curiously, the class file signature better represents the order of annotations from outer to inner.
The work has been started targeting type annotations from Java 8, because that's the long term goal and provides the greater challenge. The implementation demonstrates that a subset of these annotations can be consumed in projects at 1.7-. Technically, annotations are written as if they were type annotations on a top-level type of a field/method parameter/method return, but internally these are then interpreted as declaration annotations of the corresponding field/method parameter/method.
Existing quick fixes that are offered on compiler errors/warnings regarding null problems should be extended so that they produce external annotations instead of inserting annotations into Java source code.
Withdrawn. A quick fix of this kind would encourage people to quickly insert annotations for libraries while only looking at their own client code. Instead people should be directed to closely investigate the library and insert annotations from there. See next.
A new command "Annotate" is offered when looking at the (attached source code of) a library (technically: when working with a ClassFileEditor). This command allows users to precisely point to any type in a signature, including type parameters etc. This way not only declaration annotations but also type annotations can be attached to library methods.
In the IDE external annotations should be visualized where appropriate. Javadoc hovers and the Javadoc view show the effective annotated signature (in Java syntax). Also visualization in the outline would be interesting, but here a more compact representation would be needed, perhaps using decorations like ? and !.
The simplest approach for this community effort would be to create a forest of source repositories holding the external annotation files, either one library per repo, or "big" repos comprising multiple libraries. No new technology is needed for this.
From a technical p.o.v. even packaging external annotations as zip, uploading to some central server and discovery of these artifacts using the build technology of your choice are all straight-forward.
Issues to address here include: defining the rules and conventions for the above, and the questions whether enough people are willing to invest the effort for such manual maintenance of an external annotation packge.
To lower the barrier of contributing to a global collection of external annotations, techniques from crowd-sourcing could be integrated into the typical workflows, to automatically collect the relevant data directly from members of the crowd. This approach consists of a phase of collection and a phase of discovery.
Discovering external annotations:External plug-ins are free to analyse each project's classpath (perhaps triggered by a classpath change event), and to consult any well-known server(s) whether external annotations for referenced libraries (version) are available. If so, after download the project can simply be updated by adding the necessary extra classpath attribute to point to the external annotation attachment.
Note: You only select the location for external annotations once, so each next external annotation within this module will be stored in the same folder. Alternatively, you can specify annotations root at any time: open Project Settings dialog and go to the Modules page, then select the needed module and open its Paths tab. There you can find External annotations area, where you can manage external annotations attached to the module.
Just like when you add external annotation on the module level, you can specify the storage location right when you add the annotation, or using Project Settings dialog. In the latter case, open Project Settings dialog, go to JDKs and specify the path in the Annotations tab.
In model-based definition (MBD), getting annotations traditionally requires careful attention. You'd rather spend that time designing. That's why you need any tricks you can find that'll improve your efficiency when you're working with annotations.
You can shortcut the steps below by going to start.spring.io and choosing the "Web" starter from the dependencies searcher.Doing so generates a new project structure so that you can start coding right away.Check the start.spring.io user guide for more details.
The mvn dependency:tree command prints a tree representation of your project dependencies.You can see that spring-boot-starter-parent provides no dependencies by itself.To add the necessary dependencies, edit your pom.xml and add the spring-boot-starter-web dependency immediately below the parent section:
The gradle dependencies command prints a tree representation of your project dependencies.Right now, the project has no dependencies.To add the necessary dependencies, edit your build.gradle and add the spring-boot-starter-web dependency in the dependencies section:
Each release of Spring Boot provides a curated list of dependencies that it supports.In practice, you do not need to provide a version for any of these dependencies in your build configuration, as Spring Boot manages that for you.When you upgrade Spring Boot itself, these dependencies are upgraded as well in a consistent way.
The curated list contains all the Spring modules that you can use with Spring Boot as well as a refined list of third party libraries.The list is available as a standard Bills of Materials (spring-boot-dependencies) that can be used with both Maven and Gradle.
Spring Boot auto-configuration attempts to automatically configure your Spring application based on the jar dependencies that you have added.For example, if HSQLDB is on your classpath, and you have not manually configured any database connection beans, then Spring Boot auto-configures an in-memory database.
You are free to use any of the standard Spring Framework techniques to define your beans and their injected dependencies.We generally recommend using constructor injection to wire up dependencies and @ComponentScan to find beans.
Spring Boot ships with the BufferingApplicationStartup variant; this implementation is meant for buffering the startup steps and draining them into an external metrics system.Applications can ask for the bean of type BufferingApplicationStartup in any component.
Spring Boot lets you externalize your configuration so that you can work with the same application code in different environments.You can use a variety of external configuration sources including Java properties files, YAML files, environment variables, and command-line arguments.
@PropertySource annotations on your @Configuration classes.Please note that such property sources are not added to the Environment until the application context is being refreshed.This is too late to configure certain properties such as logging.* and spring.main.* which are read before refresh begins.
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