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Why java dosen\'t support pointers?
JohnJosephKiernan
- Jul 30th, 2006
Premm, see replies #20 and #21, and the JLS.If Java doesn't have pointers why are they mentioned in the JLS? and why does it have a NullPointerException?It doesn't have pointers with the semantics you describe: that's a different issue.IMHO what it doesn't have is *references* actually.
premmm
- Jul 29th, 2006
Hi anupamaActually, java does not use pointers.s1 is an object.Let us consider the following situation.If you write username and password in your login page using pointer. go and see the view source o...
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Why java is not 100% oops
smartcasanova
- Jan 13th, 2010
Because of the promitive data types provided in the java such as int, char float, these primitives are not objects hence Java is not pure OO.
sahit
- Oct 27th, 2009
Java does not support multiple inheritance as well as operator overloading, so we can say that Java is not completly supporting OOPs.
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If interface has got four methods,and I like to implement only two methods, how this could be achieved?
Karuna Reddy
- Jun 5th, 2008
Rest of the two method to open it and close the braces.EX:interface in1{ public void A(); &nb...
Karuna Reddy
- Jun 1st, 2008
public interface MyInterface1 { public void A(); public void B();public void C();public void D(); }package com.venkata.ust; public class MyClass1 implements MyInterface1 { @Override pu...
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What is the difference between hashmap and hashset?
sampra
- Mar 6th, 2012
HashMap is not collection inteface where as HashSet is Collection interface.
HashMap class implements Map interface where as HashSet class implements Set interface.
HashMap is prints the elements orderly where as HashSet has no order, if you need some order then go for TreeSet.maheshjammula
- Nov 28th, 2011
HashSet and hashMap both are not maintained order.Difference is hashMap contains key value to map the corresponding value but hashSet have no key value and index value.Their implementations is another matter.
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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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Abstract vs Interface Class
Which is faster at class loading - interface or abstract class? Why?
deshmukhcv
- Jul 12th, 2010
I will give the Answer with Example : Where to use Abstrace Class ::Suppose I am having class Animal. and Dog Class and Cat Class. Animal Class having method eat(). In eat() I will writ...
abhijeetsingh
- Jan 27th, 2010
In both cases differences will be negligible. It only depends upon our designing to use which one.
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Exception on finalize ()?
If Exception occurs in finalize() what happened to garbage collector? It will run or not? Explain
asanse
- May 27th, 2010
Any exception thrown by finalize() during garbage collection halts the finalization but is otherwise ignored.
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In Java, how are objects / values passed around
nnandurkar
- Jun 23rd, 2010
Java supports only pass by value. If it is a primitive then copy of the value is passed. And if it is an object then copy of its reference is passed.
sampra
- Feb 20th, 2008
In Java Object are passed by reference and Primitive data is always pass by value
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Is is true that JAVA is not 100% object oriented language ?
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Memory Allocation
What is the difference between below 2 statements?
String s1=new String("abc");String s2="abc";How it will allocate in memory?gaurav
- Jun 15th, 2012
in String s1 = "Hello World"; // "Hello world" is a constant and it will be allocated in the string pool. all the variables refering to "Hello World" constant will refer to same memory location in th...
sampra
- Mar 13th, 2012
String s1=new String("abc");- creates 2 obj one in jvm and one in pool.
String s2="abc"; no obj will create it will point to pool above already created existing obj -
If there are multiple If-else, what is the alternative algorthim we can use apart from using switch?
Prashant Shingne
- Sep 9th, 2016
We can use OOPS Concept run-time binding to call expected functionality. No need of if clause, provided everything is represented in objects.
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}
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The result wil be 5..!! and not 6 why???">Solve it... public class test {public static void main(String[] args) { int i=5; i=i++; System.out.println("result::"+i); }}The result wil be 5..!! and not 6 why???
tarazan2jungle
- May 7th, 2008
Dear Friend, this is post increment, that is first assign the value and then increment.so in this case you first assign the value, so i become 5, now you increment which is of no use.that's why the answer is 5;But rather assigning a value if you directly write i++, then the value become 6;
for4me
- May 4th, 2008
It is same as System.out.println(i++);public class test{public static void main(String[] args) ??? {??? ??? int i=5; ??? ??? System.out.println("result::"+i++); ??? }}It prints 5? first then increments.
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Why we can not override static method?
Manjunath_7_89
- Mar 25th, 2016
Static methods cannot be overridden because method overriding only occurs in the context of dynamic (i.e. runtime) lookup of methods. Static methods (by their name) are looked up statically (i.e. at c...
Ramesh
- Feb 4th, 2016
If a subclass defines a class method with the same signature as a class method in the superclass, the method in the subclass hides the one in the superclass. You didn't override the method a(), because static methods are not inherited. If you had put @Override, you would have seen an error.
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More than One Class
If more than one class is present in one Java file then what will be the java file name?
zshekhtm
- Dec 10th, 2010
You can have more than one class in the same Java source file but only one class can be public in any source file and its name should correspond to the name of a source file. This public class should have main() implemented.
annmary
- Dec 8th, 2010
If a file contain more than one class, the name that file will be the name same as the class which is declared as public. It is not mandatory.
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Synchronization in Java
When We should use Synchronization in Java and when we should not?
sivapurammani
- Dec 16th, 2013
In simple terms we can say only one thread can act on selected resource(method or variable). Understanding the above sentence is as follows:: For example we are booking any ticket in a particular bu...
Yeswanth
- Dec 6th, 2013
If you want to allow only one thread at a time to access block of code or method then we will go for synchronization.
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How do you declare constant values in java
rohitrichhariya
- Jul 23rd, 2010
For declaring constant in Java, Java gives us 3 suggestion.1. Declare constant variable as a final.2. Also constant variable declare as a final.3. All the letter of constant variable is capital....
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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...
Core Java Interview Questions
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