Java Questions

Q:

How to get contents of the folder?

Answer

File[] listFiles();


this method returns list of files stored in a directory.

Report Error

View answer Workspace Report Error Discuss

Subject: Java

0 1997
Q:

What are pass by reference and passby value ?

Answer

Pass By Reference means the passing the address itself rather than passing the value. Passby Value means passing a copy of the value to be passed.

Report Error

View answer Workspace Report Error Discuss

Subject: Java

0 1993
Q:

If super class ref is pointing sub class object then by using super class ref is it possible to call sub class newly defined method?

Answer

yes if the method is ovreriding method


no if the method is not overriding method

Report Error

View answer Workspace Report Error Discuss

Subject: Java

134 1993
Q:

When should I use abstract classes and when should I use interfaces?

Answer

Use Interfaces when…


- You see that something in your design will change frequently.


- If various implementations only share method signatures then it is better to use Interfaces.


- You need some classes to use some methods which you don't want to be included in the class, then you go for the interface, which makes it easy to just implement and make use of the methods defined in the interface.


 


Use Abstract Class when…


- If various implementations are of the same kind and use common behavior or status then abstract class is better to use.


- When you want to provide a generalized form of abstraction and leave the implementation task with the inheriting subclass.


- Abstract classes are an excellent way to create planned inheritance hierarchies. They're also a good choice for nonleaf classes in class hierarchies.

Report Error

View answer Workspace Report Error Discuss

Subject: Java

0 1989
Q:

What is difference between Path and Classpath?

Answer

Path and Classpath are operating system level environment variales. Path is used define where the system can find the executables(.exe) files and classpath is used to specify the location .class files.

Report Error

View answer Workspace Report Error Discuss

Subject: Java

0 1984
Q:

What is Thread ?

Answer

A thread is a lightweight subprocess, a smallest unit of processing. It is a separate path of execution. It shares the memory area of process.



As shown in the above figure, thread is executed inside the process. There is context-switching between the threads. There can be multiple processes inside the OS and one process can have multiple threads.

Report Error

View answer Workspace Report Error Discuss

Subject: Java

0 1973
Q:

What are wrapped classes ?

Answer

Wrapped classes are classes that allow primitive types to be accessed as objects.

Report Error

View answer Workspace Report Error Discuss

Subject: Java

0 1972
Q:

What is Auto boxing and unboxing?

Answer

Autoboxing is the process of converting a primitive type data into its corresponding wrapper class object instance.


Example:


Integer number = new Integer (100); // number is now refers to the object 100


 


Unboxing is the process of converting a wrapper instance into a primitive type.


Example: 


Integer number = new Integer (100); 


int num = number;// without type casting number would be changed into int type

Report Error

View answer Workspace Report Error Discuss

Subject: Java

0 1971