[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"me":3,"catalog:en:backend\u002Fjava-concurrency":4,"config":253},null,{"field_key":5,"field_name":6,"seniority":7,"topic_key":8,"topic_name":9,"spec_key":7,"spec_name":7,"locale":10,"cell_total":11,"field_total":12,"seniorities":13,"topics":17,"specs":148,"samples":168},"backend","Backend","","java-concurrency","Java Concurrency","en",75,3300,[14,15,16],"junior","mid","senior",[18,21,24,27,30,33,36,39,42,45,48,51,54,57,60,63,66,67,70,73,76,79,82,85,88,91,94,97,100,103,106,109,112,115,118,121,124,127,130,133,136,139,142,145],{"key":19,"name":20,"count":11},"api-design","API Design",{"key":22,"name":23,"count":11},"caching","Caching",{"key":25,"name":26,"count":11},"concurrency","Concurrency",{"key":28,"name":29,"count":11},"csharp-concurrency-async","Csharp Concurrency Async",{"key":31,"name":32,"count":11},"csharp-exceptions","Csharp Exceptions",{"key":34,"name":35,"count":11},"csharp-generics-interfaces","Csharp Generics Interfaces",{"key":37,"name":38,"count":11},"csharp-memory-performance","Csharp Memory Performance",{"key":40,"name":41,"count":11},"csharp-stdlib-http","Csharp Stdlib Http",{"key":43,"name":44,"count":11},"csharp-testing-tooling","Csharp Testing Tooling",{"key":46,"name":47,"count":11},"databases-sql","Databases \u002F SQL",{"key":49,"name":50,"count":11},"go-concurrency","Go Concurrency",{"key":52,"name":53,"count":11},"go-errors","Go Errors",{"key":55,"name":56,"count":11},"go-interfaces-generics","Go Interfaces Generics",{"key":58,"name":59,"count":11},"go-memory-performance","Go Memory Performance",{"key":61,"name":62,"count":11},"go-stdlib-http","Go Stdlib Http",{"key":64,"name":65,"count":11},"go-testing-tooling","Go Testing Tooling",{"key":8,"name":9,"count":11},{"key":68,"name":69,"count":11},"java-exceptions","Java Exceptions",{"key":71,"name":72,"count":11},"java-generics-interfaces","Java Generics Interfaces",{"key":74,"name":75,"count":11},"java-memory-jvm","Java Memory Jvm",{"key":77,"name":78,"count":11},"java-stdlib-http","Java Stdlib Http",{"key":80,"name":81,"count":11},"java-testing-tooling","Java Testing Tooling",{"key":83,"name":84,"count":11},"messaging-queues","Messaging \u002F Queues",{"key":86,"name":87,"count":11},"networking-http","Networking \u002F HTTP",{"key":89,"name":90,"count":11},"nodejs-error-handling","Nodejs Error Handling",{"key":92,"name":93,"count":11},"nodejs-event-loop-async","Nodejs Event Loop Async",{"key":95,"name":96,"count":11},"nodejs-memory-performance","Nodejs Memory Performance",{"key":98,"name":99,"count":11},"nodejs-modules-streams","Nodejs Modules Streams",{"key":101,"name":102,"count":11},"nodejs-stdlib-http","Nodejs Stdlib Http",{"key":104,"name":105,"count":11},"nodejs-testing-tooling","Nodejs Testing Tooling",{"key":107,"name":108,"count":11},"php-concurrency-async","Php Concurrency Async",{"key":110,"name":111,"count":11},"php-exceptions","Php Exceptions",{"key":113,"name":114,"count":11},"php-generics-interfaces","Php Generics Interfaces",{"key":116,"name":117,"count":11},"php-memory-performance","Php Memory Performance",{"key":119,"name":120,"count":11},"php-stdlib-http","Php Stdlib Http",{"key":122,"name":123,"count":11},"php-testing-tooling","Php Testing Tooling",{"key":125,"name":126,"count":11},"python-concurrency-async","Python Concurrency Async",{"key":128,"name":129,"count":11},"python-errors-context","Python Errors Context",{"key":131,"name":132,"count":11},"python-memory-performance","Python Memory Performance",{"key":134,"name":135,"count":11},"python-stdlib-http","Python Stdlib Http",{"key":137,"name":138,"count":11},"python-testing-tooling","Python Testing Tooling",{"key":140,"name":141,"count":11},"python-typing-oop","Python Typing Oop",{"key":143,"name":144,"count":11},"security","Security",{"key":146,"name":147,"count":11},"testing","Testing",[149,153,156,159,162,165],{"key":150,"name":151,"count":152},"csharp","C#\u002F.NET",450,{"key":154,"name":155,"count":152},"go","Go",{"key":157,"name":158,"count":152},"java","Java",{"key":160,"name":161,"count":152},"nodejs","Node.js",{"key":163,"name":164,"count":152},"php","PHP",{"key":166,"name":167,"count":152},"python","Python",[169,187,201,214,227,240],{"id":170,"topic":9,"difficulty":171,"body":172,"options":173,"correct_key":181,"explanation":186},"019f6e5f-2364-71f9-88b6-038733c5f113",1,"Whether you write `class Worker extends Thread` or `class Worker implements Runnable`, you must define the code the thread executes by overriding\u002Fimplementing one method. Which one?",[174,177,180,183],{"key":175,"text":176},"a","start()",{"key":178,"text":179},"b","call()",{"key":181,"text":182},"c","run()",{"key":184,"text":185},"d","execute()","Whether a class extends Thread or implements Runnable, the thread's task is defined by overriding\u002Fimplementing run(). start() launches a new OS thread and internally calls run(); it should never be invoked directly to 'start work'.",{"id":188,"topic":9,"difficulty":189,"body":190,"options":191,"correct_key":175,"explanation":200},"019f6e5f-239c-76a3-999c-3d7996e613f6",2,"```java\nclass DemoThread extends Thread {\n    public void run() {\n        System.out.println(\"run: \" + Thread.currentThread().getName());\n    }\n}\n\npublic class Main {\n    public static void main(String[] args) {\n        DemoThread t = new DemoThread();\n        t.run();\n        System.out.println(\"main: \" + Thread.currentThread().getName());\n    }\n}\n```\nWhat is printed for the thread name on the first line?",[192,194,196,198],{"key":175,"text":193},"main",{"key":178,"text":195},"A new thread's name, e.g. Thread-0",{"key":181,"text":197},"It throws IllegalThreadStateException at runtime",{"key":184,"text":199},"null, because the thread was never started","Calling t.run() directly is just an ordinary method invocation — no new thread is created. So Thread.currentThread() inside run() still refers to whichever thread called it, here the main thread, so it prints 'main'. Only t.start() spawns a genuinely new thread.",{"id":202,"topic":9,"difficulty":189,"body":203,"options":204,"correct_key":184,"explanation":213},"019f6e5f-23a6-7b25-b979-88ca73c78724","```java\nclass Counter {\n    private int count = 0;\n    public void increment() { count++; }\n    public int get() { return count; }\n}\n\npublic class Main {\n    public static void main(String[] args) throws InterruptedException {\n        Counter counter = new Counter();\n        Runnable task = () -> {\n            for (int i = 0; i \u003C 100_000; i++) counter.increment();\n        };\n        Thread t1 = new Thread(task);\n        Thread t2 = new Thread(task);\n        t1.start(); t2.start();\n        t1.join(); t2.join();\n        System.out.println(counter.get());\n    }\n}\n```\nWhat can you say about the final printed value?",[205,207,209,211],{"key":175,"text":206},"It always prints exactly 200000, with no exceptions",{"key":178,"text":208},"It throws a ConcurrentModificationException",{"key":181,"text":210},"It always prints exactly 100000 every single run",{"key":184,"text":212},"No exact value is guaranteed — because count++ races, it may come out less than 200000","count++ is a compound read-modify-write operation, not atomic. When two threads run concurrently without synchronization, updates can interleave and be lost, so no specific final value is guaranteed — the result may come out less than 200000 because of those lost updates.",{"id":215,"topic":9,"difficulty":189,"body":216,"options":217,"correct_key":178,"explanation":226},"019f6e5f-23a8-7e05-a48e-693aed7c00f3","Which statement correctly distinguishes `Callable\u003CV>` from `Runnable`?",[218,220,222,224],{"key":175,"text":219},"Callable can only be used with Thread, never with ExecutorService",{"key":178,"text":221},"Callable's call() can return a value and declare a checked exception; run() cannot",{"key":181,"text":223},"There is no real difference; both are used interchangeably by the compiler",{"key":184,"text":225},"Runnable can return a value from run(), but Callable never can","Callable\u003CV>.call() can return a value of type V and is allowed to throw a checked exception. Runnable.run() has a void return type and cannot declare checked exceptions. This is why Callable is used with ExecutorService.submit() when a result or a checked exception needs to be propagated.",{"id":228,"topic":9,"difficulty":189,"body":229,"options":230,"correct_key":181,"explanation":239},"019f6e5f-23aa-7138-8b2c-78f721d1425c","```java\npublic class Printer {\n    public synchronized void printTicket(int id) {\n        System.out.print(\"[\" + id);\n        System.out.println(\"]\");\n    }\n}\n```\nTwo threads repeatedly call printTicket() on the SAME Printer instance with different ids. What does synchronized guarantee here?",[231,233,235,237],{"key":175,"text":232},"The two threads run printTicket() truly in parallel for better throughput",{"key":178,"text":234},"It has no effect unless the field being modified is also declared volatile",{"key":181,"text":236},"Each printTicket() call finishes as one unit before another thread can enter",{"key":184,"text":238},"It guarantees the ids are printed strictly in ascending numeric order","A synchronized instance method acquires the monitor of `this` before executing and releases it on exit, so concurrent calls to printTicket() on the same instance are serialized — one full call completes before another begins. It says nothing about ordering by id or about running in parallel.",{"id":241,"topic":9,"difficulty":171,"body":242,"options":243,"correct_key":184,"explanation":252},"019f6e5f-23ac-700c-ac23-96aef19c5c2b","```java\nExecutorService pool = Executors.newFixedThreadPool(2);\npool.submit(() -> System.out.println(\"task 1\"));\npool.submit(() -> System.out.println(\"task 2\"));\npool.shutdown();\n```\nWhat does `pool.shutdown()` do here?",[244,246,248,250],{"key":175,"text":245},"Immediately and forcibly kills the two currently running tasks",{"key":178,"text":247},"Blocks the calling thread indefinitely until the JVM itself exits",{"key":181,"text":249},"Silently removes the two tasks from the pool without running them",{"key":184,"text":251},"Rejects new task submissions but lets already-submitted tasks finish","ExecutorService.shutdown() initiates an orderly shutdown: previously submitted tasks are executed, but no new tasks are accepted. It does not interrupt running tasks and does not block the calling thread.",{"fields":254,"seniorities":424,"interview_shapes":425,"locales":430,"oauth":432,"question_count":435,"coach_enabled":436,"jd_match_enabled":436},[255,266,286,303,327,340,359,378,398,405,411,418],{"key":5,"name_tr":6,"name_en":6,"sort":171,"specializations":256},[257,260,261,262,263,264,265],{"key":258,"name":259,"field":5},"general","Genel",{"key":154,"name":155,"field":5},{"key":166,"name":167,"field":5},{"key":157,"name":158,"field":5},{"key":150,"name":151,"field":5},{"key":160,"name":161,"field":5},{"key":163,"name":164,"field":5},{"key":267,"name_tr":268,"name_en":268,"sort":189,"specializations":269},"frontend","Frontend",[270,271,274,277,280,283],{"key":258,"name":259,"field":267},{"key":272,"name":273,"field":267},"javascript","JavaScript",{"key":275,"name":276,"field":267},"typescript","TypeScript",{"key":278,"name":279,"field":267},"react","React",{"key":281,"name":282,"field":267},"vue","Vue",{"key":284,"name":285,"field":267},"angular","Angular",{"key":287,"name_tr":288,"name_en":288,"sort":289,"specializations":290},"fullstack","Fullstack",3,[291,292,293,294,295,296,297,298,299,300,301,302],{"key":258,"name":259,"field":287},{"key":154,"name":155,"field":5},{"key":166,"name":167,"field":5},{"key":157,"name":158,"field":5},{"key":150,"name":151,"field":5},{"key":160,"name":161,"field":5},{"key":163,"name":164,"field":5},{"key":272,"name":273,"field":267},{"key":275,"name":276,"field":267},{"key":278,"name":279,"field":267},{"key":281,"name":282,"field":267},{"key":284,"name":285,"field":267},{"key":304,"name_tr":305,"name_en":305,"sort":306,"specializations":307},"devops-cloud","DevOps \u002F Cloud",4,[308,309,312,315,318,321,324],{"key":258,"name":259,"field":304},{"key":310,"name":311,"field":304},"aws","AWS",{"key":313,"name":314,"field":304},"gcp","GCP",{"key":316,"name":317,"field":304},"azure","Azure",{"key":319,"name":320,"field":304},"kubernetes","Kubernetes",{"key":322,"name":323,"field":304},"terraform","Terraform",{"key":325,"name":326,"field":304},"linux","Linux",{"key":328,"name_tr":329,"name_en":329,"sort":330,"specializations":331},"ai-engineer","AI Engineer",5,[332,333,334,337],{"key":258,"name":259,"field":328},{"key":166,"name":167,"field":328},{"key":335,"name":336,"field":328},"llm-rag","LLM\u002FRAG",{"key":338,"name":339,"field":328},"mlops","MLOps",{"key":341,"name_tr":342,"name_en":343,"sort":344,"specializations":345},"database","Veritabanı","Database",6,[346,347,350,353,356],{"key":258,"name":259,"field":341},{"key":348,"name":349,"field":341},"postgresql","PostgreSQL",{"key":351,"name":352,"field":341},"mysql","MySQL",{"key":354,"name":355,"field":341},"mongodb","MongoDB",{"key":357,"name":358,"field":341},"redis","Redis",{"key":360,"name_tr":361,"name_en":362,"sort":363,"specializations":364},"mobile","Mobil","Mobile",7,[365,366,369,372,375],{"key":258,"name":259,"field":360},{"key":367,"name":368,"field":360},"ios-swift","iOS (Swift)",{"key":370,"name":371,"field":360},"android-kotlin","Android (Kotlin)",{"key":373,"name":374,"field":360},"flutter","Flutter",{"key":376,"name":377,"field":360},"react-native","React Native",{"key":143,"name_tr":379,"name_en":144,"sort":380,"specializations":381},"Güvenlik",8,[382,383,386,389,392,395],{"key":258,"name":259,"field":143},{"key":384,"name":385,"field":143},"appsec","AppSec",{"key":387,"name":388,"field":143},"offensive-pentest","Offensive \u002F Pentest",{"key":390,"name":391,"field":143},"cloud-security","Cloud Security",{"key":393,"name":394,"field":143},"devsecops","DevSecOps",{"key":396,"name":397,"field":143},"blue-team-incident","Blue Team \u002F Incident",{"key":399,"name_tr":400,"name_en":401,"sort":402,"specializations":403},"qa-test-automation","QA \u002F Test Otomasyonu","QA \u002F Test Automation",9,[404],{"key":258,"name":259,"field":399},{"key":406,"name_tr":407,"name_en":407,"sort":408,"specializations":409},"data-engineer","Data Engineer",10,[410],{"key":258,"name":259,"field":406},{"key":412,"name_tr":413,"name_en":414,"sort":415,"specializations":416},"game-dev","Oyun Geliştirme","Game Development",11,[417],{"key":258,"name":259,"field":412},{"key":419,"name_tr":420,"name_en":420,"sort":421,"specializations":422},"ml-engineer","ML Engineer",12,[423],{"key":258,"name":259,"field":419},[14,15,16],{"junior":426,"mid":428,"senior":429},{"questions":427,"median_sec":3},20,{"questions":427,"median_sec":3},{"questions":427,"median_sec":3},[431,10],"tr",[433,434],"google","github",21750,true]