Category: Java

Guava version compatibility issue

Spring Boot errors Pure Java exceptions Suggested solutions Method Guava version com.google.common.base.Preconditions.checkArgument 26.0-jre / 26.0-android com.google.common.base.Preconditions.checkState 21.0 com.google.common.util.concurrent.MoreExecutors.sameThreadExecutor 18.0 / 19.0 Let me remind you that guava with maven is connected like this: If suggested verions don’t fix the problem, you can try connecting the specified versions in order: 18.0 / 19.0 / 21.0 / […]

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Load x509 certificate from keystore Java

We have a keystore with an imported certificate and we need to work with it in code. We are going to import cert into an X509Certificate class object. After that, you can work with it further, or simply display some information about it, for example: Subject X500 Principal, Issuer X500 Principal Subject DN, Issuer DN […]

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Failed to find reentrant lock with given name Ignite

Full text of the exception in Apache Ignite: The code that uses the reentrant lock looks something like this: Check that when creating a lock, the last argument = true is passed to the reentrantLock method: If the error is still repeated, then this is a bug: https://issues.apache.org/jira/browse/IGNITE-3386. It appears when one of the server […]

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Error creating shaded jar target\classes (Access is denied)

The error looks like this: Stacktrace: maven-shade-plugin tries to open classes folder as zip file. This happens when one of the dependencies is found on the local filesystem and not in the local maven repository. Before unpacking, the plugin should check whether target\classes is a directory or a zip file, but it doesn’t. One solution […]

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JAAS / Kerberos / Digest stub with Mockito

You need to test the functionality of method X. It does the following things: Performs authentication using JAAS; If authentication is successful, it continues to work. It’s often problematic to set up a working authentication mechanism in a unit test environment. One solution to the problem is to set a stub on the login() method […]

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REST endpoint stub in Java

Making a REST server Let me remind you that earlier we talked about setting up a REST server for unit tests in JUnit. We will also be using the WireMock tool today. Information about adding WireMock to the project can be found in the previous article. Configuring server parameters For HTTP: For HTTPS: To use […]

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REST endpoint stub in JUnit

Suppose you want to test method X. It requests data from a specific endpoint Y. In this article, we’ll talk about three things: how to start a REST server within a unit test; how to set up data transmission on Y; how to check the number of requests received on Y. For information on how […]

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SSL / TLS setup for ZooKeeper

We have a ZooKeeper server and a java client application that connects to it. SSL has appeared in ZooKeeper since version 3.5.: https://issues.apache.org/jira/browse/ZOOKEEPER-2125 Server Tuning There are several types of ZooKeeper server distribution. We’ll cover the standalone version as well as the Apache Kafka version. We need a configured server for start. The setup process […]

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                   Mark Chesnavsky. Email me or connect via LinkedIn.