Rarely asked Interview Questions and Answers

Interview Questions and Answers - Order By Rating

Q61. What data type Variable can be used in a switch statement ?

Core Java

Ans. Variables used in a switch statement can only be a byte, short, int, or char ( and String with Java 7 and above )

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Q62. What is the Locale class?

Ans. The Locale class is used to tailor program output to the conventions of a particular geographic, political, or cultural region

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Q63. What is Externalizable interface?

Core Java

Ans. Externalizable is an interface which contains two methods readExternal and writeExternal. These methods give you a control over the serialization mechanism.

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Q64. Difference between PATH and CLASSPATH ?

Operating System

Ans. PATH is the variable that holds the directories for the OS to look for executables. CLASSPATH is the variable that holds the directories for JVM to look for .class files ( Byte Code ).

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Q65. What is a ConcurrentHashMap ?

Core Java

Ans. ConcurrentHashMap is a hashMap that allows concurrent modifications from multiple threads as there can be multiple locks on the same hashmap.

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Rarely asked as default methods have been introduced with Java 8.

Q66. Can we have a default method without a Body ?

Core Java

Ans. No. Compiler will give error.

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Q67. What is Closeable ?

Core Java

Ans. A Closeable is an interface which is a source or destination of data that can be closed.

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Q68. Name few Locale classes and interfaces ?

Ans. http://www.buggybread.com/2015/01/java-locale-classes-and-interfaces.html

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Rarely asked as it was introduced with Java 8.

Q69. Which keyword specify that a variable is effectively final ? a. final b. No Keyword c. Both of the above d. None of the above

Core Java

Ans. No Keyword

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Q70. What is RI or Reference Implementation ?

Ans. RI or Reference Implementation is a sample implementation provided for the API's / Specs, usually by their developers. This is usually a part of API documentation.

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Q71. What is GregorianCalendar class ?

Ans. This class provides support for traditional Western calendars.

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Q72. In which cases , moving methods to utility class could be useful ?

Core Java

Ans. It could be worthy to move a method to util class if the method needs to be shared, doesn't require polymorphic behavior and need not be overridden in special cases.

Don't belong to one group through is-a relationship ( You can share through parent class method )

Don't implement a specific interface ( java 8 default methods )

Doesn't involve complex computing as you will be loosing the benefit of object state with just static method.

Doesn't require polymorphic behavior as static methods don't participate in runtime polymorphism.

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