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Question: What is the difference between == and .equals() in Java?
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Answer: You can find the difference below:
• The == operator is used for reference comparison, i.e., to check if two objects reference the same memory location.
• And .equals() is a method used for content comparison, i.e., to check if two objects have the same content or values.
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Question: What is the difference between ArrayList and LinkedList in Java?
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Answer: Please find the difference below:
• ArrayList uses a dynamic array to store elements, providing fast random access and slower insertion/deletion.
• LinkedList uses a doubly linked list to store elements, providing fast insertion/deletion and slower random access.
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Question: What is polymorphism in Java?
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Answer: In Java Polymorphism refers to the ability of an object to take many forms. In Java, it can be achieved
through method overriding and method overloading.
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Question: What is the difference between String, StringBuilder, and StringBuffer in Java?
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Answer: In Java:
• String is immutable
• StringBuilder is mutable and not thread-safe
• StringBuffer is mutable and thread-safe.
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Question: What is the difference between abstract class and interface in Java?
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Answer: Below please find the main difference:
• An abstract class can have both abstract and concrete methods, while an interface can only have abstract methods.
• A class can implement multiple interfaces but can extend only one abstract class.
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Question: What is the final keyword in Java?
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Answer: The final keyword in Java is used to:
• To declare constants
• To prevent method overriding
• To make classes immutable.
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Question: Explain the concept of Exception Handling in Java?
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Answer: Exception Handling in Java is the process of handling runtime errors that occur during program execution.
It involves using try, catch, and finally blocks to handle exceptions and maintain program flow even in case of errors.
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Question: What is the difference between HashMap and HashTable in Java?
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Answer: Please find the difference below:
• HashMap is not synchronized and allows null values, while HashTable is synchronized and does not allow null values.
• HashMap is faster but not thread-safe, while HashTable is slower but thread-safe.
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