>From chatgpt4

The problem appears to be that there is a mismatch between the version of
Scala used by the Scala Maven plugin and the version of the Scala library
defined as a dependency in your POM. You've defined your Scala version in
your properties as `2.12.17` but you're pulling in `scala-library` version
`2.13.6` as a dependency.

The Scala Maven plugin will be using the Scala version defined in the
`scala.version` property for compilation, but then it tries to load classes
from a different Scala version, hence the error.

To resolve this issue, make sure the `scala.version` property matches the
version of `scala-library` defined in your dependencies. In your case, you
may want to change `scala.version` to `2.13.6`.

Here's the corrected part of your POM:

```xml
<properties>
  <maven.compiler.source>1.7</maven.compiler.source>
  <maven.compiler.target>1.7</maven.compiler.target>
  <encoding>UTF-8</encoding>
  <scala.version>2.13.6</scala.version> <!-- Here's the change -->
  <maven-scala-plugin.version>2.15.2</maven-scala-plugin.version>
</properties>
```

Additionally, ensure that the Scala versions in the Spark dependencies
match the `scala.version` property as well. If you've updated the Scala
version to `2.13.6`, the artifactIds for Spark dependencies should be
`spark-core_2.13` and `spark-sql_2.13`.

Another thing to consider: your Java version defined in
`maven.compiler.source` and `maven.compiler.target` is `1.7`, which is
quite outdated and might not be compatible with the latest versions of
these libraries. Consider updating to a more recent version of Java, such
as Java 8 or above, depending on the requirements of the libraries you're
using.



The same problem persists in this updated POM file - there's a mismatch in
the Scala version declared in the properties and the version used in your
dependencies. Here's what you need to update:

1. Update the Scala version in your properties to match the Scala library
and your Spark dependencies:

```xml
<properties>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
    <encoding>UTF-8</encoding>
    <scala.version>2.13.6</scala.version> <!-- updated Scala version -->
    <maven-scala-plugin.version>2.15.2</maven-scala-plugin.version>
</properties>
```

2. Make sure all your Spark dependencies use the same Scala version. In
this case, I see `spark-streaming-kafka_2.11` which should be
`spark-streaming-kafka_2.13` if you're using Scala `2.13.6`.

```xml
<dependency>
    <groupId>org.apache.spark</groupId>
    <artifactId>spark-streaming-kafka_2.13</artifactId> <!-- updated to
2.13 -->
    <version>1.6.3</version> <!-- this might also need to be updated as
this is a very old version -->
    <scope>provided</scope>
</dependency>
```

3. As mentioned in the previous message, your Java version
(`maven.compiler.source` and `maven.compiler.target`) is also quite
outdated. Depending on the requirements of the libraries you're using, you
might want to update this to a newer version, such as Java 8 or above.

Finally, ensure that the correct versions of these libraries exist in your
Maven repository or are available in the central Maven repository. If the
versions don't match, Maven will not be able to find and download the
correct dependencies, which can lead to problems.

Please note that it's crucial to maintain consistency in your Scala and
Java versions across your project and its dependencies to avoid these kinds
of issues. Mixing versions can lead to binary incompatibility errors, such
as the one you're seeing.







The differences in behavior between SBT and Maven when resolving Scala
dependencies can be attributed to how they each handle Scala binary
versions.

SBT is specifically designed for Scala projects and has built-in support
for handling Scala's binary compatibility issues. When you define a Scala
library dependency in SBT, you can specify the Scala binary version as
"_2.12", "_2.13", etc. in the library artifact name. SBT will then
automatically replace this with the actual Scala binary version defined in
your SBT configuration. So, if you've defined different Scala versions for
your project and for a specific dependency, SBT will handle this gracefully.

Maven, on the other hand, is more generic and does not have the same level
of built-in support for Scala's binary versions. In Maven, the Scala
version is typically hardcoded in the artifact name, and if this doesn't
match the actual Scala version used in your project, it can lead to binary
compatibility issues.

This difference between SBT and Maven means that a project can work fine
when built with SBT but fail when built with Maven, due to these Scala
version discrepancies. To avoid these issues in Maven, you need to ensure
that the Scala version is consistent across your project configuration and
all your dependencies.

Also, another reason for this can be because SBT often fetches dependencies
on the fly, while Maven requires them to be explicitly declared. SBT can
download and link the correct Scala library version even if it's not
explicitly declared, while Maven will only use the versions that have been
specified in the POM file.

To summarize, SBT is more flexible and Scala-oriented than Maven, which can
lead to different behavior when handling Scala dependencies. When using
Maven for Scala projects, it's essential to ensure that all Scala versions
match across the project.

søn. 28. mai 2023 kl. 21:03 skrev Mich Talebzadeh <mich.talebza...@gmail.com
>:

> This compilation works fine with SBT but fails with maven!
>
> Spark version 3.4.0
> Apache Maven 3.9.2 (c9616018c7a021c1c39be70fb2843d6f5f9b8a1c)
> Java version: 11.0.1, vendor: Oracle Corporation, runtime: /opt/jdk-11.0.1
>
> This from the pom.xml file
>
> <project xmlns="https://maven.apache.org/POM/4.0.0"; xmlns:xsi="
> https://www.w3.org/2001/XMLSchema-instance";
> xsi:schemaLocation="https://maven.apache.org/POM/4.0.0
> https://maven.apache.org/maven-v4_0_0.xsd";>
> <modelVersion>4.0.0</modelVersion>
> <groupId>spark</groupId>
> <version>3.0</version>
> <name>${project.artifactId}</name>
>
> <properties>
> <maven.compiler.source>1.7</maven.compiler.source>
> <maven.compiler.target>1.7</maven.compiler.target>
> <encoding>UTF-8</encoding>
> <scala.version>2.12.17</scala.version>
> <maven-scala-plugin.version>2.15.2</maven-scala-plugin.version>
> </properties>
> <dependencies>
>   <dependency>
>     <groupId>org.scala-lang</groupId>
>     <artifactId>scala-library</artifactId>
>     <version>2.13.6</version>
>   </dependency>
>   <dependency>
>     <groupId>org.apache.spark</groupId>
>     <artifactId>spark-core_2.13</artifactId>
>     <version>3.4.0</version>
>     <scope>provided</scope>
>   </dependency>
>   <dependency>
>     <groupId>org.apache.spark</groupId>
>     <artifactId>spark-sql_2.13</artifactId>
>     <version>3.4.0</version>
>     <scope>provided</scope>
>
> The pom file is attached. These are the errors I am getting
>
> [ERROR] error: error while loading package, class file
> '/home/hduser/.m2/repository/org/scala-lang/scala-library/2.13.6/scala-library-2.13.6.jar(scala/reflect/package.class)'
> is broken
> [ERROR] (class java.lang.RuntimeException/error reading Scala signature of
> package.class: Scala signature package has wrong version
> [ERROR] error: error while loading package, class file
> '/home/hduser/.m2/repository/org/scala-lang/scala-library/2.13.6/scala-library-2.13.6.jar(scala/package.class)'
> is broken
> [ERROR] (class java.lang.RuntimeException/error reading Scala signature of
> package.class: Scala signature package has wrong version
> [ERROR] error: error while loading package, class file
> '/home/hduser/.m2/repository/org/scala-lang/scala-library/2.13.6/scala-library-2.13.6.jar(scala/collection/package.class)'
> is broken
> [ERROR] (class java.lang.RuntimeException/error reading Scala signature of
> package.class: Scala signature package has wrong version
> [ERROR] three errors found
> [ERROR] Failed to execute goal
> org.scala-tools:maven-scala-plugin:2.15.2:compile (default) on project
> scala: wrap: org.apache.commons.exec.ExecuteException: Process exited with
> an error: 1(Exit value: 1) -> [Help 1]
>
> Any ideas will be appreciated.
>
> Mich Talebzadeh,
> Lead Solutions Architect/Engineering Lead
> Palantir Technologies Limited
> London
> United Kingdom
>
>
>    view my Linkedin profile
> <https://www.linkedin.com/in/mich-talebzadeh-ph-d-5205b2/>
>
>
>  https://en.everybodywiki.com/Mich_Talebzadeh
>
>
>
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