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Can we override the main method?
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ashish_setia- Member Since Oct-2006 | Oct 3rd, 2006
check out this example
class Checkmain{
public static void main(String args[]){
args[1]="ashish";
System.out.println("hello ");
}
}
class Checkmain1 extends Checkmain{
public static void main(String args[]){
System.out.println("how r u");
}}
class Jo{
public static void main(String args[]){
String S[]=new String[10] ;Checkmain.main(S);
Checkmain1.main(S);
}}vivek
- Aug 26th, 2017
Yes you can only do that by overriding main method signature for eg main(String[] args) to main(). Certainly there are no other ways to do that because JVM needs strings array arguments to take comma...
Dharmendra Singh
- Sep 15th, 2016
yes we can"java public class HelloWorld { // arguments are passed using the text field below this editor public static void main(String[] args) { String []s =new Str...
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Output of Java Program
What is the output of the following program?class A{ public static void main(String[] s) { System.out.println(s[1] + s[2] + s[3]);}}java A 12345Options(i) 1(ii) 12(iii)1234(iv)234(v) Compilation Error
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abuthahir.d- Member Since Jan-2008 | Apr 14th, 2008
Khadar , i tried this code . it gives that exception
for the foll reason :
when u give a CLA(command line argument) , it will be inserted in the index 0 of the array and then will proceed to 1 ,2 ....
so as per the question , "12345" will be at s[0] . and length of that aray will be 1when u try to access s[1] , we are trying for 2nd element which is unavailable.....
Hope this answers u :-)shyamasundar
- Jun 2nd, 2018
(v) Compilation Error
shani
- Mar 14th, 2018
(v) Compilation Error
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Is java a fully object oriented programming or not? if not why?
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KanikaKG- Member Since Jul-2008 | Aug 4th, 2008
No. Java is not 100 % Pure OOP because of following three reasons:
1) It doesnot support Multiple inheritance.
2) It allows use of primitive data types which are not an objects.
3) It allows static methods to call without creating the instance.
This disobeys OOPs concepts?
Java isnt 100% pure OOPS coz if it were then everything should be classes and objects, whereas java still has primitive data type which violates the above said statement...SmallTalk is the only 100% pure OOPS languageChaitra
- Jun 6th, 2019
Java is not a pure object oriented programming language because of the primitive data type.
But java can be made 100% object oriented programming language by making use of wrapper classes.Amit Kumar
- May 21st, 2018
Sorry, I am completely agree that java is a pure object oriented language. First of all answer me one question , what do you mean by object oriented programming ? object oriented programming is a conc...
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What is the difference between abstract class & Final class
Manjunath_7_89
- Mar 25th, 2016
Abstract Class
1. Could be Inherited.
2. Couldnt instatiated.
3. Could add few more methods.
4. Incomplete class
Final Class
1. Final version of Class
2. Couldnt be inherited.
3. Could be instantiated.
4. Couldnt add any more methods.baban
- Feb 11th, 2016
Abstract class cannot create object but final class create a object
abstract class which have must a subclassed but final class which have no subclassed -
What is MVC architecture
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Answered by: Mitchel K
- Jun 27th, 2005
A design pattern describes a proven solution to a recurring design problem, placing particular emphasis on the context and forces surrounding the problem, and the consequences and impact of the solution.
There are many good reasons to use design patterns. Here are three:
1) They are proven. You tap the experience, knowledge and insights of developers who have used these patterns successfully in their own work.
2) They are reusable. When a problem recurs, you don't have to invent a new solution; you follow the pattern and adapt it as necessary.
3) They are expressive. Design patterns provide a common vocabulary of solutions, which you can use to express larger solutions succinctly.
The goal of the MVC design pattern is to separate the application object (model) from the way it is represented to the user (view) from the way in which the user controls it (controller).
The MVC architecture has the following benefits:
1) Multiple views using the same model: The separation of model and view allows multiple views to use the same enterprise model. Consequently, an enterprise application's model components are easier to implement, test, and maintain, since all access to the model goes through these components.
2) Easier support for new types of clients: To support a new type of client, you simply write a view and controller for it and wire them into the existing enterprise model.
3) Clarity of design: By glancing at the model's public method list, it should be easy to understand how to control the model's behavior. When designing the application, this trait makes the entire program easier to implement and maintain.
4) Efficient modularity: of the design allows any of the components to be swapped in and out as the user or programmer desires - even the model! Changes to one aspect of the program aren't coupled to other aspects, eliminating many nasty debugging situations. Also, development of the various components can progress in parallel, once the interface between the components is clearly defined.
5) Ease of growth: Controllers and views can grow as the model grows; and older versions of the views and controllers can still be used as long as a common interface is maintained.
6) Distributable: With a couple of proxies one can easily distribute any MVC application by only altering the startup method of the application.yura
- Dec 2nd, 2015
Everyone explained what is MVC... This is outcome of one more design pattern called "separation of concerns", which means a "view" should only handle rendering logic of the model and should not be co...
Anil Nivargi
- Jun 26th, 2014
The MVC consists of three kinds of Objects i.e Model,View and Controller. Lets start explaining one by one. 1) Model- It handles data processing and database works part. Model processes event...
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Why java is not 100% object oriented language??
i have not ..asked in TCS interview ..if any one have plz answer me on er.anuj.mittal@gmail.com
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Find the Output
class A{ public static void main(String[] a){ System.out.print(String.valueOf(1)+String.valueOf(2)); String s1="s1"; String s2=s1.toString(); System.out.print(","+(s1==s2)); }}
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Overriding Methods
Suppose a Super Class method throws an exception and this method is Overriden in the subclass with no exception. Now if you create a super class reference that has a subclass object. This throws a compile time error, Why?
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bharathnav- Member Since Oct-2008 | Oct 13th, 2008
"Suppose a Super Class method throws an exception and this method is Overriden in the subclass with no exception. Now if you create a super class reference that has a subclass object. This throws a compileLatest Answer: Because at run time, the super class will compiled first, so it will gives the run time error. ..."
if the object has been created to the subclass and both the methods are non static then the method we overriden doesn't produce any errors or exceptions.sampra
- Mar 6th, 2012
If the object has been created to the subclass and both the methods are non static then the method we overriden doesnt produce any errors or exceptions.
techbuz
- Dec 23rd, 2011
throws exception in super class doesnt affest over-riding:code eg as follows: "java public class Ride{ void clay(){ System.out.println("am in base class"); } public static voi...
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What is the Output of the following Java Program
public interface I1{Static String x="inside I1";public void someMethod();}class A implements I1{ public static void main(String args[[]){ System.out.println("Calling I1 var ..."+I1.x);}}
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abuthahir.d- Member Since Jan-2008 | Apr 14th, 2008
Compilation error due to 2 reasons.
1. All variables defined in the Interfaces are implicitly public static final. So need not specify "Static" in interface.
2. If any of the member functions of a Interface is not Overriden , a compilation error will be thrownshanu_rastogi
- Feb 3rd, 2010
It is right that you dont need to explicitly define a varible static but if you do so then it will not give compliler error..
sarojmohanty
- Nov 19th, 2009
Compilation error will come because you must have to override the abstract method of the implememted interface. After the implementation of the abstract method the program will compile and run properly and print "inside l1".
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Object Creation
In how many ways we can create an object? Explain with example.
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vishrutha- Member Since Feb-2009 | Feb 13th, 2009
1. Using new keyword
This is the most common way to create an object in java. I read somewhere that almost 99% of objects are created in this way.MyObject object = new MyObject();
2. Using Class.forName()
If we know the name of the class & if it has a public default constructor we can create an object in this way.MyObject object = (MyObject) Class.forName("subin.rnd.MyObject").newInstance();3. Using clone()
The clone() can be used to create a copy of an existing object.MyObject anotherObject = new MyObject();
MyObject object = anotherObject.clone();4. Using object deserialization
Object deserialization is nothing but creating an object from its serialized form.ObjectInputStream inStream = new ObjectInputStream(anInputStream );
MyObject object = (MyObject) inStream.readObject();5. Using class loader
one more is through creation of object using classloader likethis.getClass().getClassLoader().loadClass(com.amar.myobject).newInstance();
Now you know how to create an object. But its advised to create objects only when it is necessary to do so.
sampra
- Mar 13th, 2012
There are 5 ways:
1-> new operaotor
2-> Class.forName()
3-> Cloning
4-> Deserialization
5-> Class.newInstance()Max
- Sep 7th, 2011
All sorts of syntax sugar can also be named: 6. New String as a result of concatenation: String varName = getClass().getName(); //to avoid compile-time optimization String a = "Prefix" + varName; ...
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Can a method be static and synchronized
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Answered by: Srimant Misra
- Aug 12th, 2005
A static method can be synchronized. If you do so, the JVM will obtain a lock on the java.lang.Class instance associated with the object. It is similar to saying:
synchronized(XYZ.class)
{
}Akii
- May 21st, 2013
If you synchronized on static method ,its lock on class level not only that method.
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How would you pass a java integer by reference to another function
Mayank
- Mar 13th, 2018
I don't think that is right because if it was then changing the value inside the called function should reflect the change when the passed variable is accessed in calling function.
sourabharvikar3
- May 4th, 2011
what is point behind sending integer by reference???Still if you want to do so... lookclass Demo{private int i;public static void main(String[] ar){ Demo d=new Demo();&nb...
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Null keyword
Is null a keyword? if not what is it?
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interviewprep9- Member Since Jun-2008 | Jun 14th, 2008
Capital N, Null is not a keyword or a reserved word.
All small letters, null is not a keyword either. but, it's a reserved word. you cannot use null as follows:
String null = "a";
null means that a reference is not pointing to any object.
Sarje
- Aug 17th, 2009
Null is not a keyword but null is reserved literal. null is the default value for instance variable.String str = null;means instance variable str does not hold reference of any object.
varmasuman
- Sep 13th, 2008
Null?means showing nothingWhenever one object reference refers null i.e? ServletConfig application=null;Then there is nothing in the object reference application.
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Need of Polymorphism
What is need of polymorphism in Java? What could have happen if polymorphism is not present?
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syamala235- Member Since Mar-2010 | Apr 8th, 2010
Polymorphism in simple terms means one name many forms. Polymorphism enables one entity to be used as a general category for different types of actions. The specific action is determined by the exact nature of the situation.
Polymorphism exists in three distinct forms in Java:
• Method overloading
• Method overriding through inheritance
• Method overriding through the Java interfacePrashant kumar gupta
- Oct 28th, 2017
We have different behaviors in different situations and in front of different people. A man behaves differently with his father, when he is with his friend he has different behavior. Another best exa...
suraj
- Jun 19th, 2017
Polymorphism means one thing in many form. or one person different behavior is called polymorphism.
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In overriding, in super class we declared a method as protected & in sub class we declared that method as private. what happens?
vinaymudgil007
- Jun 4th, 2008
Well the answer to orignal question asked is -- compilation errorlogic --> In a subclass we can't make the method more restrictive than what is there in the super class.vinny
Core Java Interview Questions
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