Rego Digital Solutions Java Developer Interview Questions and Answers

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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They give one API Task

Easy

Q1. Tell me about yourself Why you choose IT & developer role OOPs concept, sample Java program
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Q1. Personal and salary details.
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Q1. How can you create immutable class in Java?
Ans. 
Immutable class in Java cannot be modified after creation, ensuring data integrity.
• Make the class final so it cannot be extended

• Make all fields private and final so they cannot be modified

• Do not provide setter methods, only getter methods to access the fields

• If the class contains mutable objects, make sure to return a deep copy of them in getter methods
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Q2. 1 : Declare the class as final. 2 : Make all fields private and final. 3 : Provide no setter methods.
Ans. 
The question is asking to create a class with certain restrictions like being final, having private and final fields, and no setter methods.
• Declare the class as final to prevent it from being subclassed.

• Make all fields private and final to ensure encapsulation and immutability.

• Provide no setter methods to enforce read-only access to the fields.
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Q1. Oops Concepts ,Absrtraction,Polymorphism
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Q1. What is the purpose of static keyword in Java?
Ans. 
The static keyword in Java is used to create class-level variables and methods that can be accessed without creating an instance of the class.
• Static variables are shared among all instances of a class.

• Static methods can be called without creating an instance of the class.

• Static blocks are used to initialize static variables.

• Static keyword can also be used to create static nested classes.
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Q2. The static keyword is used to create class-level variable and methods ............etc.
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Q.1 Pattern
1
*2*
**3**
Q. 2
write code to get sub array with max sum from given array.

Q1. Introduction Project Deatails Oops Concept Collection Exception Handling Abstract Class Functional Interface Spring Framework
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Q1. What is the difference between ==and .equals() in java?
Ans. 
In Java, == compares memory addresses while .equals() compares the actual content of objects.
• == compares memory addresses of objects, while .equals() compares the actual content of objects.

• == is used to compare primitive data types, while .equals() is used to compare objects.

• Example: String str1 = new String("hello"); String str2 = new String("hello"); str1 == str2 will be false, but str1.equals(str2) will be true.
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Q2. ==compares object references, while .equals() compares object values in java.
Ans. 
In Java, == compares object references, while .equals() compares object values.
• Use == to compare if two object references point to the same memory location.

• Use .equals() to compare if two objects have the same values.

• Example: String str1 = new String("hello"); String str2 = new String("hello"); str1 == str2 will be false, but str1.equals(str2) will be true.
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