Fourth Dimension Technologies Java Developer Interview Questions and Answers for Experienced

Q1. Oops Concepts ,Absrtraction,Polymorphism
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Questions on string and arrays both are moderate level questions on hacherrank type for 20 marks

Q1. Constructor chaining
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Q2. Hasmap and treemap
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2 questions solve on paper

Q1. Basic java questions and adv java ,sql,css,html questions
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Q1. All about core java
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Q2. Front end and My Sql
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Based on JavaScript and Java.

A task based on JavaScript.

It was online 60min test.

It was offline 30 min test.

Q1. Oops,dbms,css,html,dsa,java.
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Q2. It was very friendly .
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Q1. What are the 4 principles of oops?
Ans. 
The 4 principles of OOP are Inheritance, Encapsulation, Abstraction, and Polymorphism.
• Inheritance allows a class to inherit properties and behavior from another class.

• Encapsulation restricts access to certain components within a class, protecting the data.

• Abstraction hides complex implementation details and only shows the necessary features.

• Polymorphism allows objects to be treated as instances of their parent class.
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Q2. What is the difference between string buffer and string builder?
Ans. 
String buffer is synchronized and thread-safe, while string builder is not synchronized and faster.
• String buffer is synchronized, making it thread-safe for use in multi-threaded environments.

• String builder is not synchronized, providing better performance in single-threaded applications.

• String builder is faster than string buffer due to lack of synchronization overhead.

• Example: StringBuffer sb = new StringBuffer(); Str
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Q3. Why strings are immutable?
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Strings are immutable in order to ensure data integrity and security.
• Immutable strings prevent accidental data modification, ensuring data integrity.

• Immutable strings enhance security by preventing unauthorized access or tampering.

• Immutable strings allow for more efficient memory management and optimization.

• Example: 'Hello' cannot be changed to 'Hella' directly, a new string must be created.
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Q4. What are the different types of exception in java?
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There are two types of exceptions in Java: checked exceptions and unchecked exceptions.
• Checked exceptions are checked at compile time and must be handled using try-catch or throws keyword.

• Unchecked exceptions are not checked at compile time and include RuntimeException and its subclasses.

• Examples of checked exceptions include IOException, SQLException, and ClassNotFoundException.

• Examples of unchecked exceptions include...read more
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Q5. Explain linear search algorithm.
Ans. 
Linear search is a simple searching algorithm that sequentially checks each element in a list until a match is found.
• Iterate through each element in the list

• Compare the current element with the target value

• Return the index if a match is found, otherwise return -1
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Q6. Difference between JDK jvm and jre
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JDK includes JRE and development tools, while JRE includes only the Java Runtime Environment.
• JDK stands for Java Development Kit, which includes JRE and development tools like compilers and debuggers.

• JRE stands for Java Runtime Environment, which includes JVM and libraries necessary to run Java applications.

• JVM stands for Java Virtual Machine, which is responsible for executing Java bytecode.

• JDK is used for developing ...read more
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30 min test on simple google form

Half hour conding round on basic javascript questions

One hour coding round on little bit intermediate javascript questions