Interview Questions and Answers for 'T' | Search Interview Question

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Frequently asked to fresh graduates.

Q1921. Difference between Process and Thread ?

Operating System

Ans. Process is a program in execution whereas thread is a separate path of execution in a program.

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Frequently asked to fresh graduates.

Q1922. What is a Deadlock ?

Operating System

Ans. When two threads are waiting each other and cant precede the program is said to be deadlock.

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Q1923. Difference between Serialization and Deserialization ?

Core Java

Ans. Serialization is the process of writing the state of an object to a byte stream. Deserialization is the process of restoring these objects.

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Q1924. Explain Autoboxing ?

Core Java

Ans. Autoboxing is the automatic conversion that the Java compiler makes between the primitive types and their corresponding object wrapper classes

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Q1925. What is an Enum type ?

Core Java

Ans. An enum type is a special data type that enables for a variable to be a set of predefined constants

Sample Code for enum

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Q1926. What are Wrapper Classes ? What are Primitive Wrapper Classes ?

Core Java

Ans. A wrapper class is any class which "wraps" or "encapsulates" the functionality of another class or component. A Wrapper Class that wraps or encapsulates the primitive data type is called Primitive Wrapper Class.

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Q1927. What Design pattern Wrapper Classes implement ?

Design

Ans. Adapter.

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Q1928. What is "Import" used for ?

Core Java

Ans. Enables the programmer to abbreviate the names of classes defined in a package.

Sample Code for import

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Q1929. Different types of memory used by JVM ?

Core Java

Ans. Class , Heap , Stack , Register , Native Method Stack.

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Q1930. What is a class loader ? What are the different class loaders used by JVM ?

Core Java

Ans. Part of JVM which is used to load classes and interfaces.

Bootstrap , Extension and System are the class loaders used by JVM.

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Q1931. Can we declare interface methods as private ?

Ans. With Java 9 we can declare interface methods as private

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Q1932. What is a Static import ?

Core Java

Ans. By static import , we can access the static members of a class directly without prefixing it with the class name.

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Very frequently asked. Usually difference between String,StringBuffer and StringBuilder is asked in different variations.

Q1933. Difference between StringBuffer and StringBuilder ?

Core Java

Ans. StringBuffer is synchronized whereas StringBuilder is not.

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Q1934. Difference between Map and HashMap ?

Core Java

Ans. Map is an interface where HashMap is the concrete class.

Sample Code for map

Sample Code for hashmap

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Q1935. What is a Property class ?

Core Java

Ans. The properties class is a subclass of Hashtable that can be read from or written to a stream.

Sample Code for Load Properties using Property Class

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Very frequently asked in different variations. Frequently asked in Deloitte ( 2 feedback ) , HCL Tech ( 3 feedback ), TCS and Coginizant (CTS)

Q1936. Explain the scenerios to choose between String , StringBuilder and StringBuffer ?

or

What is the difference between String , StringBuilder and StringBuffer ?

Core Java

Ans. If the Object value will not change, use String Class because a String object is immutable.

If the Object value can change and will only be modified from a single thread, use StringBuilder because StringBuilder is unsynchronized(means faster).

If the Object value may change, and can be modified by multiple threads, use a StringBuffer because StringBuffer is thread safe(synchronized).

Sample Code for String

Sample Code for StringBuffer

Sample Code for StringBuilder

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Q1937. Explain java.lang.OutOfMemoryError ?

Core Java

Ans. This Error is thrown when the Java Virtual Machine cannot allocate an object because it is out of memory, and no more memory could be made available by the garbage collector.

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Q1938. Can we have multiple servlets in a web application and How can we do that ?

Java EE

Ans. Yes by making entries in web.xml

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Q1939. How can we manage Error Messages in the web application ?

Solution

Ans. Within message.properties file.

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Frequently asked to fresh graduates.

Q1940. Is JVM, a compiler or interpretor ?

Ans. Its an interpretor.

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Q1941. Difference between implicit and explicit type casting ?

Ans. An explicit conversion is where you use some syntax to tell the program to do a conversion whereas in case of implicit type casting you need not provide the data type.

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Q1942. Should we override finalize method ?

Ans. Finalize is used by Java for Garbage collection. It should not be done as we should leave the Garbage Collection to Java itself.

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Q1943. What is assert keyword used for ?

Ans. The assert keyword is used to make an assertionâ€”a statement which the programmer believes is always true at that point in the program. This keyword is intended to aid in testing and debugging.

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Q1944. Difference between Factory and Abstract Factory Design Pattern ?

Design

Ans. Factory Pattern deals with creation of objects delegated to a separate factory class whereas Abstract Factory patterns works around a super-factory which creates other factories.

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Q1945. Difference between Factory and Builder Design Pattern ?

Design

Ans. Builder pattern is the extension of Factory pattern wherein the Builder class builds a complex object in multiple steps.

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Q1946. Difference between Proxy and Adapter ?

Design

Ans. Adapter object has a different input than the real subject whereas Proxy object has the same input as the real subject. Proxy object is such that it should be placed as it is in place of the real subject.

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Q1947. Difference between Adapter and Facade ?

Design

Ans. The Difference between these patterns in only the intent. Adapter is used because the objects in current form cannot communicate where as in Facade , though the objects can communicate , A Facade object is placed between the client and subject to simplify the interface.

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Q1948. Difference between Builder and Composite ?

Ans. Builder is a creational Design Pattern whereas Composite is a structural design pattern. Composite creates Parent - Child relations between your objects while Builder is used to create group of objects of predefined types.

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Q1949. Example of Chain of Responsibility Design Pattern ?

Ans. Exception Handling Throw mechanism.

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Q1950. Example of Observer Design Pattern ?

Ans. Listeners.

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