Updated: Apr 24, 2022
every time one wants to start a new project, usually the requirements for solving the problem have to be faced. which server should i pick, which database to take and which programming language should i use? the last question will be subject of this article. there a lot of measurements one can help to see if a programming language is fitting or not, so lets get started.
popularity among developers
if celebrities do something interesting or are likeable, the internet, magazines and people do start talking about them. the same goes for a programming language. if a programming language has a nice syntax, is less verbose or is fast, people most likely start talking about it, asking questions about it, get in touch with it and finally picking it for the next project. all this benefits the reputation of a programming language. the website tiobe.com for example analyzes the result count of search queries of many search engines like google or bing to measure the popularity of a programming language.  a similar approach is documented on pypl.github.io by measuring search results of of tutorials on google only.  redmonk.com on the other hand measures the activity of posts tagged with the specific programming language on stackoverflow and on the other hand repositories scanned and tagged on github. 
if a software has or had a bad reputation, it is very hard to get rid of it. it takes lots of years to change peoples perception about a product, a good example is the new microsoft edge web browser, it also uses the same chromium browser, like google chrome does, but it is still considered slow because of the former implementation and the internet explorer. the same goes for java, before the introduction of the just in time (jit) compilation in java code was interpreted and not compiled, execution times and the start up times were very slow. with the release of java 1.2 the jit compiler was only a slight improvement but advanced in every new major release of the next releases. today measurements show that java is one of the fastest programming languages (top 5). yet, java is considered slow. the aftermath is still present nowadays. nevertheless, the popularity is still sufficient to be one of the most popular programming languages (top 5), based on the stack overflow survey in 2021.  but to be fair, java is being loved and hated at the same time  and the popularity is going down over the last 10 years. 
another metric is to count the job offers from different websites. counting the offers by programming language shows how high the demand of a specific programming language can be. the british website itjobswatch.co.uk shows the demand for programming in the united kingdom.  here java is also a highly requested language (top 5). linkedin has a similar statistics showing java also in the top 5. 
sadly there is no data of people actually accepting these jobs. some of the vacancies might be online with no actual candidates applying to these open positions. it could be useful to see this information like ebay does. one can search for successfully finished auctions to see the real value of a product, in our case the programming language.
last of all one can have personal preferences for choosing a programming language. a developer might be very confident with a language and therefor is more effective than picking a new programming language for every upcoming project and that might be one reason to stick to an already personally preferred language. in my personal working space we call this the comfort zone.
habits and experience can be strong arguments picking the same programming language, but one shouldn't overdo this. sticking with the same language for a too lange time can cause the opposite. you can get blind for things evolving around you ending as the last action script developer of the extinct adobe flash.  try sometimes to read about upcoming changes in your preferred programming language, but also look up what others do and prefer.
so all in all it is not that easy picking the perfect programming language for a project. the decision can depend on requirements, experience, personal taste, open market situations or other factors. as long as you do a little research and do a decision open minded you can avoid choosing a language which slows you down or is even a deadlock in a future state. be careful and curious.