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1. Can You catch the Error? 2. Difference between compiletime exception and runtime exception?3. How you throw user defined exception?4. How you handle throwable while using exceptions ?5. What are the methods available in Object ?6. Is there any methods available in serialization ?7. How you seralize an Object ?8.How you get the serialized object ? 9. Any methods available in deseralization ?
rammaheswara
- Sep 29th, 2009
Yes, you can catch the Error as it is a subclass of Throwable, but you are not supposed to.For most of the errors like ( out of memry), there is no use of catching the error.MAHES
ambuj
- Jun 28th, 2007
No, because error is not related to ur progamming envirnment through which we can apply our exception handling mecanism. It?occurs only due to operating system failure, System virus affected etc.
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How We Can We write our own exceptions?
maddy_me
- Sep 22nd, 2009
we can write our own exceptions by extending them either from Throwable or from Exception.class Example1{ public static void main(String[] args) throws MyException { ...
d
- Mar 9th, 2006
To write our own Exception class1)Our class must be subclass of Throwable or Exception class2)Evert Exception class provide 2 constructors a) no arguments b) one argument i.e String argument3) Optional: Overidding toString metod of java.lang.Object
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Convert string object to primitive Integer Type
How can i convert a string object to a primitive Integer type???????Thanks
maddy_me
- Sep 18th, 2009
class StringConver{ public static void main(String[] s) { //String s1 = "Hello"; If you try this you will get NumberFormatException ...
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What does the state consists of for an Object which has to be serialized?
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Marker interface having no methods right.. then what is the use of marker interface? for what purpose we use marker interface?
Ravi.Hingarajiya
- Aug 27th, 2009
It is used to identify class. In the read project, there are so many classes. It can identify that which class belongs to which module Exmaple : Cloneable interface can be cloned. The Java compi...
amitabh26d
- Aug 26th, 2009
Marked interfaces is for compiler use and we need not have to worry about its implementation.? Yes it does not have any methods, it is because by implementing marked interfaces we are telling a compiler?that it can optimise this class as per the specification of Java for that interfaces.
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SetEx setEx1 = new SetEx("Java");
String str1 = new String("Java");
String str2 = new String("Java");
s.add(setEx);
s.add(setEx1);
s.add(str1);
s.add(str2);
System.out.println("No Of elements in the Set is " + s.size());
}
What is the result and how?">Import java.util.*;public class SetEx { private String str; SetEx(String s) { str = s } public static void main(String[] ar) { Set s = new HashSet(); SetEx setEx = new SetEx("Java"); SetEx setEx1 = new SetEx("Java"); String str1 = new String("Java"); String str2 = new String("Java"); s.add(setEx); s.add(setEx1); s.add(str1); s.add(str2); System.out.println("No Of elements in the Set is " + s.size()); }What is the result and how?
james.vinett
- Aug 24th, 2009
The result is 3 even though you would want it to be 2.You MUST override equals() and hashCode() for proper use of add in HashSet.
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What is "JIT ENGINE" in Java?
james.vinett
- Aug 24th, 2009
The just-in-time compiler compiles byte code into native machine language when it first encounters it and then reuses that compiled code rather than recompiling it again. This give performance gains over the interpreter model which interprets the byte code every time it encounters it.
sampra
- Feb 14th, 2008
jit reads the whole byte code and exceute once where as interpretaor does it by line by line
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What is the difference between instance,object,refference,class.
Give the answer
Sarje
- Aug 19th, 2009
Class : A class is category of the object (any real entity) and acts as blueprint to create such object.For example if you want to develop an application for any company then its employee will be yo...
priya
- Dec 25th, 2005
Class : A class is a user defined data type with set of data members & member functionsObject : An Object is an instance of a classReference : A reference is just like a pointer pointing to an objectInstance :This represents the values of data members of a class at a particular time
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How to compare Stringbuffer objects?
Sarje
- Aug 19th, 2009
Since java.lang.StringBuffer class does not override equals(Object obj) method of the Object class then so you can not compare its objects directly. If you want to compare its objects then first conve...
rameshbabukm
- May 26th, 2007
The Known fact is the stringbuffer strore the data as charcter array, so when when we do a append on the stringbuffer object it inserts the chars into that array.Thats why we got method which can very the initial capacity of the same.hope it clarifies the doubt?
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">
Does Java have "goto"?
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How i can validate the user, Is there any java api is there for that. Or i can use my one business logic. If both are possible, Then which one is the best way for real time.
Need some information
Sarje
- Aug 19th, 2009
If you are talking about the web application and you are preparing it using JSP and Servlet then you have to write your own bussiness logic to validate the user information. For server side validation...
chowdary
- Nov 8th, 2005
Our own business logic is the best solution because it is more efficient than the api.java Api is common for all,so it may not efficient for all but ur logic is best for ur project.
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What is mutable and immutable in Strings?
Sarje
- Aug 19th, 2009
immutabe string means once string is created you can not insert or append or remove any character from the string. Since java.lang.String class is immutable thess operations are not allowed in it.muta...
sunil belurgikar
- Sep 29th, 2005
Mutable string means we can append to that string.example StringBuffer object is mutable string.String is immutable objectwhen we declre String="abc"; a string object abc with fixed length is created.We cant add anything to it .If we do java simply creates a new object.
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Implement Interface using Polymorphism
How an interface can be implemented using polymorphism?Why multiple inheritence is not used in Java?
Sarje
- Aug 18th, 2009
I think your question is how to achieve Runtime Polymorphism using using interface.then the answer is :interface MyInf{ void show();}class A implements ...
shouvanik1979
- Mar 30th, 2009
Polymorphism means "one form many actions". Lets say, a class Test implements an interface ITest. Accordingly,public interface ITest{ public void testMethod();}//a class implemen...
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What type of access specifiers can we use for local variables?
Sarje
- Aug 18th, 2009
Local variable cannot be modified using any of the acceess specifiers means you can not write private or protected or public before them.Local variables are by default (implicitly)? private no need to make it explicitly private or protected or public otherwise it won't compile.
er.mukesh_208
- Aug 3rd, 2008
Local variables (including formal parameters) are visible only in the method, constructor, or block in which they are declared. Access modifiers (private, public, ...) can not be used with local var...
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Restrict a Class
How can we restrict a class so that no instance creation of class possible without declaring the class as Abstract ?
Sarje
- Aug 18th, 2009
Only abstract classes can not be instantiated. If you make the constructor private then you can not instantiate it outside of the class but you can still instantiate it within the same class.
sriragv
- Jun 21st, 2009
1. By creating a private constructor2. By giving abstract key word to the class
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How to make a class immutable (like String)?
Sarje
- Aug 18th, 2009
immutable means once object is created then you can not make any change to it. if you try to do so then new object will be created and original object will be lost.final modifier is used to indicate t...
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Access Specifier
What will happen if same access specifier repeats more than once within a class?
Sarje
- Aug 17th, 2009
Multiple Acceess Specifier cannot be used with a class because it makes no sense and if you do so compile time error(wrong combination of modifiers) will be generated.
12srinu12
- Nov 7th, 2008
If the same access specifiers are used for the methods in the same class nothing will happen. Problem occurs only when all the classes in the program are assigned with same access specifiers.
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Read Number Methods
How many methods to read numbers and characters and what should be used.
Sarje
- Aug 17th, 2009
Methods in InputStream to read byte and in Reader to read character are -int read()int read(byte buffer[])int readIbyte burrer[],int offset,int numBytes)
inthiyaj
- May 9th, 2009
We have readers and streams. Readers are used to read characters and streams are used to read bytes, streams returns numbers i.e. byte number.
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Null keyword
Is null a keyword? if not what is it?
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Editorial / Best Answer
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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What is the difference between an object and an instance? And give me a real time example to differentiate these two?
Sarje
- Aug 15th, 2009
object and instance both are sameI think you want know the difference between reference and object.If so thenreference of any class type is a variable that can hold the reference(more or less we can s...
pravinsharma
- Oct 15th, 2008
An object is part of a process/thread which demands processor time through the JVM.The act of creating the object from a class is called instantiation.In literary sense an instance is existance/occurrence of an object.In this case a duplicate copy(instance) of an object is still the same object.
Core Java Interview Questions
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