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

Core Java Interview Questions

Questions Answers Views Company eMail

My interview asked what is dynamic variable in java and where we use them.

IBM,

2 7743

"we cannot create an object of interface but we can create a variable of it".diacuss the statement with the help of an example.

2 7821

Can I create any Marker Interface? If yes then how can I use it???

4 11807

please send code example of inner classes?

2 5612

what is the use of clone method? why user cant overwrite in sub class without its proper defination.

TCS,

2 6426

what is object deep copy and shallow copy and why it is required?

2 9073

what is the use of Clonable,and serializable interface?

1 23263

Can an interface extands a class?

5 10211

Can i have abstract class with no abstract methods?

CTS,

22 48023

what are upcasting and downcasting?

5 18536

what is the diff b/w arraylist and vector?

Code Genesis, Genesis, Sprintine Labs,

6 11915

What is actual difference between statement,prepared statement and callable statement and when we have to use it? pls post a answer with code and clear explanation. thanks

2 14410

Write an algorithm program in java for the following question.. 1) S is a set of integers.X is an integer obtained by sum of two digits in S. Write logic for whether or not the X is from the S. The time of algorithm should not exceed o(n logn).

2232

Write an algorithm program in java for the following question.. In a VLSI design techniques,they used rectangles to design circuits. EVery rectangle is to be placed according to x,y coordinates. Check whether or not two rectangles overlap each other. Here overlapping of rectangles is acceptable, if 1) one rectangle intersect with other. 2) one rectangle fully covers other. The time of algorithm should not exceed o(n logn).

2776

can we access the super class method using subclass object?

4 8543

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Un-Answered Questions { Core Java }

Draw a UML class diagram for the code fragment given below: public class StringApplet extends Applet { private Label sampleString; private Button showTheString; private ButtonHandler bHandler; private FlowLayout layout; public StringApplet() { sampleString = new Label(" "); showTheString = new Button (" Show the String"); bHandler = new ButtonHandler(); layout = new FlowLayout(); showTheString.addActionListener(bHandler); setLayout(layout); add(sampleString); add(showTheString); } class ButtonHandler implements ActionListener { public void actionPerformed(ActionEvent e) { samplestring.setText("Good Morning"); } } } Note: The methods need not be indicated on the diagram.

2105

What is a concrete classes? Is Java object class is concrete class?

1032

What do you know about the garbate collector?

1090

Is it possible to compare various strings with the help of == operator? What are the risks involved?

1134

How many types of design patterns are there?

1170

What is difference between == equals () and compareto () method?

1100

How to sort array in descending order in java?

966

What is t in generics in java?

1137

What is the difference between a vector & an array list?

1221

What is default exception handling in java?

1071

Can a static class have a constructor java?

1035

What is runtime polymorphism or dynamic method dispatch?

1051

What was java originally called?

1007

Can we make a constructor final?

1084

What is space character in java?

1177

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