Core Java Interview Questions, Answers for Freshers and Experienced asked in various Company Job Interviews

Core Java Interview Questions

Questions Answers Views Company eMail

printstream class method println() is calling using System class and its static object out .how it is explain any one in detail with example ?

TCS,

1 5389

whats the purposr of using serialization?

6 9692

how to one war file class to another war file class?

2076

suppose in a class there is a code like this: { Set hs=new Hashset(); hs.add(new Emp("kathy",1000)); hs.add(new Emp("kathy",2000)); } how can u avoid the above code in your class as set won't allow duplicate objects?

3 6622

what is meant by UP& DOWN casting in java?

6 14477

how can we import the user defined package without classpath?

CSC, Infosys,

1 7766

Write a java program to find the route that connects between Red and Green Cells. General Rules for traversal 1. You can traverse from one cell to another vertically, horizontally or diagonally. 2. You cannot traverse through Black cells. 3. There should be only one Red and Green cell and at least one of each should be present. Otherwise the array is invalid. 4. You cannot revisit a cell that you have already traversed. 5. The maze need not be in the same as given in the above example

2600

For ease of programming you can consider the maze as a 2D array with colors represented by below integer and characters (in capital letters). • B - Black • W -White • G- Green • R- Red R B W B W W W W W W B W B B W W W W W W W B W B W W W B W W W W B B W W W B W W W B W W B B B B W B W B W W B W W W B W W W B B B W W B W W W B W W B W B W W W B W B W W W W B B W W W W B W W W W W G Shortest Route Problem: • Solution that finds the shortest Route between Red and Green  White will have 1 Weight.  Red and Green carry no weights.  Shortest path is the path with less weight when you add up the weights in the path.

2017

what is j2se

3 6374

we have two threads..both the threads are reading the data.. is there any need of synchronization there?...justify it?

IBM,

4 8353

what is unreachable code problem in multiple catch statements

3 6591

where lives in jvm

5 8926

What is "Java Native Interface" and how to use it?

IBM,

1 6004

What is the diff. b/w Interfaces & Abstract class?

Ericsson,

6 10464

Which of these methods belong to Thread & Object class? join, yield, sleep, wait, notify

Ericsson,

3 10140

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Un-Answered Questions { Core Java }

Where is core java used?

1012

Explain about the performance aspects of core java?

1054

Given a singly linked list, determine whether it contains a loop or not without using temporary space?

988

What are sets in java?

946

What does s mean in regex?

1019

Does java set allow duplicates?

1083

What is the difference between quicksort & mergesort? When should they be used? What is their running time?

1089

Why javac is not recognized?

942

What is the benefit of inner / nested classes ?

988

What is the difference between the size and capacity of a vector?

1041

What is a copy constructor in java?

1124

Explain about interrupt() method of thread class ?

1126

When will we use them?

1052

What is formatted output in java?

967

Why are getters and setters used?

1060

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