Java interview questions asked By Companies(Tavant Technologies,3pillar,TSP,HCL,Conduent)
Questions asked in Tavant Technologies
1) Difference between following statements:-
String s1 = “ABC”;
String s2 = new String(“ABC”);
and how many objects will be created in memory?
2) Difference between String and String buffer and String builder?
3) What is immutable and why String is immutable?
4) How to create an immutable class ?
5) How to create a Singleton class ?
6) Can we make a constructor private ?
7) Can we create a final constructor ?
8) How many ways to create a Singleton class ?
9) How to restrict the creation of an object of a singleton class through a copy
constructor ?
10) What is Serialization and Deserialization ?
11) Can we achieve Singleton by using serialization?
12) Can we Deserialize an object again and again ?
Questions by 3pillar
1) Get() and load()
2) Delete and truncate in mysql
3) return type of put in hashmap and add in hashset().
4) Internal working of hashmap and hashset.
5) Java 8 features.
6) Grow factor of Arraylist,Hashmap,hashset.
7) Functional interface with example.
8) Concurrency.
9) Method of object class.
10) Why wait,notify,notifyall are in object class.
11) Most efficient join in mysql.Why
12) Fail fast and fail safe.
13) Proxy object in hibernate.
Questions asked in The Silicon Partner(TSP)
● There were four 4 online tests:-
1) Can we create and access non static members inside static method?
2) Try with resource
3) fork and join
Questions asked in HCL
1) Request options -> HEAD, TRACE, PUT, POST, OPTIONS
2) Upsert query
3) Insert with on conflict.
4) Eureka discovery.
5) @PathVariable can be null with primitive ,boolean ,string
Questions asked in Conduent
1) Difference between List and Set
2) Internal working of HashMap
3) What is serialization and SerialVersionUUID and what is the role of
SerialVersionUUID in Serialization
4) If Object is modified after serialization, then Will we get same object by
deserializing it.
5) What is CopyOnWriteArrayList and it’s uses and internal working
6) What is difference between failSafe and failFast and how fail fast is detected
internally
7) Difference between Post and Put
8) What are the methods of Restful web service
9) What is the idempotent request/method
10) What is the Producer and Consumer problem? What is the real scenario to
use it?
11) Difference between Spring and Spring Boot
12) Working of ConcurrentHashMap
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