Java, Python, Quick solutions, Uncategorized

How to solve: pick elements from one list, that indexes are stored in second list

Today I am going to show you how to create a list combined with those elements from one list, that have indexes collected in the second list. For my example I will use python, because I have a little contact with it recently at my work.

def main():
    x = ['a', 'b', 'c', 'd', 'e']
    y = [1, 2, 3]
    z = [x[_] for _ in y]

if __name__ == "__main__":

Script presented above solves exactly the issue, which was presented in the topic.  You may ask, what underscore (‘_’) sign means in this case. It represents each and every element in the list and helps to iterate over them without necessity of describing it in a direct way. It can be substituted with another variable crated in place by parser. The same thing is achieved in stream API of Java 8 with lambdas, but single underscore sign is not allowed it this case:

IntStream.range(1, 4).map(_a -> _a * 2).forEach(System.out::print);

Python code should print list containing three elements like below:

[‘b’, ‘c’, ‘d’]

Mockito, Quick solutions

How to solve: mocking chained calls

I have met this issue several times, so I decided to give the simplest solution to you. You have probably had a situation, when you need to return one object, but it demanded mocking each and every object in the middle. You can avoid that by adding parameter to you mocked object like:

@Mock(answer = Answers.RETURNS_DEEP_STUBS)
private Client elasticSearchClient;

private ClusterHealthRequestBuilder healthRequestBuilder;

Currently you can use when() as presented below:


instead of mocking AdminClient, ClusterAdminClient and ClusterHealthRequestBuilder by hand:

ptivate AdminClient admin;
private ClusterAdminClient cluster;
private ClusterHealthRequestBuilder clusterHealthRequestBuilder;

public void setUp() {
Hibernate, Quick solutions, Spring Framework

How to solve: java.lang.IllegalArgumentException: Not an managed type

This is the first post of series “quick solutions”.

I have met issue mentioned in the topic in my current job. The reason occurred to be pretty simple. I have written wrong path in packagesToScan parameter of LocalContainerEntityManagerFactoryBean.

public EntityManagerFactory entityManagerFactory() throws PropertyVetoException {
    HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();

    LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();

    return factory.getObject();

As a side note, Hibernate forces us to have default constructor (without params) in all managed entities, but exception is different then and looks more like the one I pasted below:

org.hibernate.InstantiationException: No default constructor for (…)