Resolving mutually exclusive dependency conflicts:

Using strict versions, you will effectively depend on the version you declare, even if a transitive dependency says otherwise.

Sometimes we come in the situation to exclude transitive dependency.

Enforcing a dependency version, Example 3. In practice, larger libraries or frameworks can bring in a huge set of dependencies. Gradle Shadow Plugin The library author's dependency toolkit User Guide → John Engelman - …

The biggest of them is the subtle errors. Strict dependencies are to some extent similar to Maven’s nearest first strategy, but there are subtle differences: strict dependencies don’t suffer an ordering problem: they are applied transitively to the subgraph, and it doesn’t matter in which order dependencies are declared. For example, B might say, instead of strictly 1.0, that it strictly depends on the [1.0, 2.0[ range, but prefers 1.0.

In particular, a strict version will override any other strict version on the same module found transitively. Excluding a transitive dependency for a particular dependency declaration, Example 5. Since you don’t need these duplicate files in your application, the simplest way of doing is to tell the build system to exclude the files altogether.

Over a million developers have joined DZone. As the producer, a strict version will effectively behave like a force: the version declaration takes precedence over whatever is found in the transitive dependency graph.

By this, you tell Gradle that a dependency between two modules is never needed — i.e. If you are developing a library, you have to be aware that this information is not published, and so sometimes an exclude can be the better alternative. Then this would trigger a resolution error because A says it needs C:1.1 but B, within its subgraph, strictly needs 1.0. If you use excludes, make sure that you do not utilise any code path requiring the excluded dependency by sufficient test coverage. For example, the first copy of the class file will be considered by the build system and will be used, and the subsequent same class files appearing for the second time are ignored. exclude: only the first found duplicate file is copied and 'wins'. This also happens because of the duplicate class files. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Select View > Tool Windows > Gradle (or click Gradle in the tool windows bar).

Gradle resolves any dependency version conflicts by selecting the latest version found in the dependency graph. This can be seen as implicitly defining a feature variant that has not been explicitly declared by commons-beanutils itself. Expand AppName > Tasks > android and double-click androidDependencies. Since you don’t need these duplicate files in your application, the simplest way of doing is to tell the build system to exclude the files altogether. After Gradle executes the task, the Run window should open to display the output. Opinions expressed by DZone contributors are their own. if the source code of the project depends on an older API of a dependency than some of the external libraries. If, for some reason, you can’t use strict versions, you can force a dependency doing this: If the project requires a specific version of a dependency on a configuration-level then it can be achieved by calling the method ResolutionStrategy.force(java.lang.Object[]).

Forcing a version of a dependency requires a conscious decision.

Historically, excludes were also used as a band aid to fix other issues not supported by some dependency management systems. If you are getting “DuplicateFileException: Duplicate files copied in APK”, just make sure that you are not repeatedly calling same dependencies. Thus the same file, when included more than once, makes a duplicate error. This is only an example to illustrate potential pitfalls. For example, here we use the setSimpleProperty() method to modify properties defined by setters in the Person class, which works fine. If you are authoring and publishing a library, you also need to be aware that force is not published. forced dependencies suffer an ordering issue which can be hard to diagnose and will not work well together with other rich version constraints.

You may consider to look into the following features: Update or downgrade dependency versions: Gradle Goodness: Handle Copying Duplicate Files, Developer Transitive dependencies can be excluded on the level of a declared dependency. 0-alpha1) and classes. The following build file create four task of type Copy, each with a different duplicate strategy.

For more information about managing dependencies in Gradle, see Dependency management basics in the Gradle User Guide. From mobile apps to microservices, from small startups to big enterprises, Gradle helps teams build, automate and deliver better software, faster.

Even if this looks easier, there are a number of drawbacks in such builds. Using this method for existing setters does not require any functionality from commons-collections as we verified through test coverage. See the original article here. Zeplin is an awesome desktop application that can be used as a tool for collaboration…, As of now, Android Studio needs a fast and stable internet connection to implement a…, In the previous post, you have seen how to install Eclipse IDE, ADT, and the Android…, Your email address will not be published. If those libraries fail to declare features separately and can only be consumed in a "all or nothing" fashion, excludes can be a valid method to reduce the library to the feature set actually required. Moving Layout from Zeplin to Android Studio, Use gradle zip in local system without downloading it everytime using gradle-wrapper, Android Application Development Lesson – 2 – Environmental Variables, Solved – Cannot resolve symbol Android Studio.

However, for consumers, strict versions are still considered globally during graph resolution and may trigger an error if the consumer disagrees.

A dependency version can be enforced by declaring it as strict it in the build script: Using a strict version must be carefully considered, in particular by library authors.

It is more often that you see DuplicateFileException: Duplicate files copied in APK META-INF/.. errors in the Gradle build system. Duplicate entry for class in gradle.
However, because the error handling path uses a class from commons-collections, the error we now get is NoClassDefFoundError: org/apache/commons/collections/FastHashMap. Enforcing a dependency version on the configuration-level, Example 4. Since the set doesnot support duplicate entries, you will get only unique elements left with TreeSet.

Since Gradle has no first-class support for Maven BOMs, you can use Spring’s Dependency management plugin.

This dependency is called transitive dependency. Consider upgrading your source code to use a newer version of the library as an alternative approach.

if the source code of the project depends on an older API of a dependency than some of the external libraries.
Another situation that you often see solved by excludes is that two dependencies cannot be used together because they represent two implementations of the same thing (the same capability).

Let’s say a project uses the HttpClient library for performing HTTP calls. Solved – DuplicateFileException: Duplicate files copied in APK META-INF/.. // compile files('libs/httpmime-4.3.5.jar'), '', "org.apache.httpcomponents:httpcore:4.x.x", "org.apache.httpcomponents:httpmime:4.x.x", 'org.apache.httpcomponents:httpmime:4.x.x'. Similar as forcing a version of a dependency, excluding a dependency completely requires a conscious decision. For example archive tasks also implements this interface. Required fields are marked *. In Java, it is typical that if you include the same class file twice or more in a classpath, the duplicates are automatically ignored. Here httpclient is already in the group httpcomponents, so basically you’re duplicating httpclient. Example 2. So if there are multiple dependencies on a library, excludes are only exercised if all dependencies agree on them. Here in the first line of code, you are including all the jar files in the libs directory, and then in the second line again httpmine.jar is included which is also from the same libs directory, which makes a duplication. For example, if we add opencsv as another dependency to our project above, which also depends on commons-beanutils, commons-collection is no longer excluded as opencsv itself does not exclude it. In our code, shown below, we only use one method from the beanutils library, PropertyUtils.setSimpleProperty(). You might have encountered another problem similar to this, the “Multiple dex files defined” problem. 0-milestone-9 does not include debug information about local variables. In this example, we add a dependency to commons-beanutils but exclude the transitive dependency commons-collections. conflicting strict dependencies will trigger a build failure that you have to resolve. In the directories src/manual and src/website we have a file COPY.txt. Effectively, we are expressing that we only use a subset of the library, which does not require the commons-collection library. For this reason, a good practice is that if you use strict versions, you should express them in terms of ranges and a preferred version within this range. For copy operations, the. For example, here’s how generally files get duplicated.

Marketing Blog. In Gradle we can configure how duplicate files should be handled by the Copy task.

We must use the setDuplicatesStrategymethod to configure how Gradle behaves. Now, a consumer, A, depends on both B and C:1.1. Excluding a transitive dependency might lead to runtime errors if external libraries do not properly function without them. For example, If you were using two jars which contain common META-INF files, then you are duplicating the META-INF files. Forcing dependencies via ExternalDependency.setForce(boolean) is deprecated and no longer recommended: In the example above, A would have to say it strictly depends on 1.1.

The concept is simple, In a Gradle build, you are not allowed to include a file more than once with the same path. warn : shows a warning on the console, but the last duplicate file 'wins' like with the include strategy. strict dependencies can be used with rich versions, meaning that it’s better to express the requirement in terms of a strict range combined with a single preferred version. However, the production source code of the project requires an API from Commons Codec 1.9 which is not available in 1.10 anymore. You can unsubscribe at any time. Also, make sure that you’re not duplicating the dependencies. When it happens without you knowing it’s indeed a creepy topic. For the reason that Gradle system doesn’t need any ordering of things, it becomes one of the most compatible build systems.