Java Classes Questions And Answers

1⟩ A stack stores data using first-in, last-out ordering.A) TrueB) False

Yes it is true ... Stack works on the Startegy of First In First Out

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2⟩ This can be used inside any method to refer to the current objectA) TrueB) False

Answer is False and i got it wrong inspite of being correct!!

Explanation:

this cannot be used within a static method. It can be used only within non-static methods.So the question asks whether it can be used inside any method......

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3⟩ The type of data returned by a method need not be compatible with the return type specified by the methodA) TrueB) False

Explanation: The type of data returned by a method must be compatible with the return type specified by the method. For example, if the return type of some method is boolean, you could not return an integer

A) its False

The return type must be compatible

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4⟩ By using finalization, you can define specific actions that will occur when an object is just about to be reclaimed by the garbage collector.A) TrueB) False

True.

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5⟩ What is meant by OO paradigm?

OO paradigm = Object Oriented Paradigm.

This is the basic concept of Object Oriented Languages.It actually means we have to only work out with objects.Communications take place between classes with the help of objects

Ex:- Java,C++ ,But not C(Function Oriented)

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6⟩ Methods that have a return type other than void return a value to the calling routine using the following form of the return statementreturn value;A) TrueB) False

It's TRUE

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7⟩ The data, or variables, defined within a class are called _______ variablesA) ObjectB) ClassC) InstanceD) None of the above

Class variables

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8⟩ Explain how to create connectionpooling in Tomcat?

Please share your answers.

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9⟩ Explain why the StringBuffer and the wrapper classes defined as final?

By defining a class as final we are restricting the one of the main feature of OOP ie., INHERITANCE. But JavaSoft(SUN) has provided this restricting feature because Java Developers thought that some methods cannot be modified by the users. Eg. for those are the methods in String , StringBuffrer ,StringBuilder , all Wrapper classes. As String is a standard class those methods should be as they are as developed by Sun. The user can not be permitted to change the functionality of those methods. If your application needs this type of situation u can decalre your class as final.

The user can't implement the method toUppercase( ) in String class as that it can convert only some of the characters into Uppercase.

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10⟩ How to load a class from a remote server?

How can classes are loaded from remote server? Don't worry.... please visit the hypelink and will get your ans.... http://java.sun.com/developer/JDCTechTips/2001/tt0227.html#dynamic

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11⟩ Tell me is it ok to say interfaces, classes are of polymorphism(i.e we can use those for different purposes). if not then why?

Inorder to reduce memory space and accessing the class members without instanciate Object is the Interface which will contain only abstract methods

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12⟩ Suppose I have a rtf file generated out of jasper report.I want to print this file.I tried using Runtime.getRuntime().exec.But, it is not printing.My questions are How to print the file and how do I specify the path of the file for printing?

Please share your answers.

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13⟩ In Java it is possible to define two or more methods within the same class that share the same name, as long as their parameter declarations are differentA) TrueB) False

Yes it is True ...

In Java we can have to or more classes with the same name but the parameter list should be Different ... This Concept is called

Method Overloading or Function Overloading

In C++ we have the same Concept too ..

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14⟩ Stacks are controlled through two operations traditionally called _ and ___A) Push and PullB) Push and PopC) Pop and PullD) Pop and Peep

Ans is :(B)push and pop

Push :Push is used to insert elements in the stack.

Pop : Pop is used to extract elements from the stack.

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15⟩ Methods declared as static have several restrictions1) They can only call other static methods.2) They must only access static data.3) They cannot refer to this or super in any way Which of these are TRUE?A) 1 and 2B) 1 and 3C) 2 and 3D) 1, 2 and 3

Ans is :(c)

b'coz static methods can call static as well as non static methods.

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16⟩ In this example class-var = new classname( ); The class name followed by parentheses specifies the _________ for the classA) VariablesB) ConstructorC) ObjectsD) Memory

Constructor

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17⟩ If the method does not return a value, its return type must be voidA) TrueB) False

It's true. If a method is not returning any value then we must have to specify it's return type as void.void indicates that method is not returning any value.

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18⟩ What is the difference between instantiation & initialization?

Instance ation will not allocate memory, just a instance will be created.

Initialization will actually allocate memory.

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19⟩ In System.out.println() explain it.My doubt, we call static method with Class name but here what is "out"?

Actually System is class define in java.lang package...

class System{ //Member variables... static PrintStream out;

.................................

//Member methods...

.................

}

so out is a static reference of PrintStream class,which is define in java.io package and println() is a method of PrintStream class...

So ultimately, we can call println() method of static out reference of System class.

Syste.out.println();

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20⟩ What is difference between abstract class and interface?

1. Abstract class is a class which contain one or more abstract methods, which has to be implemented by sub classes. Interface is a Java Object containing method declaration and doesn't contain implementation. The classes which have implementing the Interfaces must provide the method definition for all the methods.

2. Abstract class is a Class prefix with a abstract keyword followed by Class definition. Interface is a Interface which starts with interface keyword.

3. Abstract class contains one or more abstract methods. where as Interface contains all abstract methods and final declarations.

4. Abstract class contains the method definition of the some methods. but Interface contains only method declaration, no definition provided.

5. Abstract classes are useful in a situation that Some general methods should be implemented and specialization behavior should be implemented by child classes. Interfaces are useful in a situation that all properties should be implemented we can use this scenario

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Java Classes

Home Java Programing Java Classes

76 Java Classes Questions And Answers

1⟩ A stack stores data using first-in, last-out ordering.A) TrueB) False

2⟩ This can be used inside any method to refer to the current objectA) TrueB) False

3⟩ The type of data returned by a method need not be compatible with the return type specified by the methodA) TrueB) False

4⟩ By using finalization, you can define specific actions that will occur when an object is just about to be reclaimed by the garbage collector.A) TrueB) False

5⟩ What is meant by OO paradigm?

6⟩ Methods that have a return type other than void return a value to the calling routine using the following form of the return statementreturn value;A) TrueB) False

7⟩ The data, or variables, defined within a class are called _______ variablesA) ObjectB) ClassC) InstanceD) None of the above

8⟩ Explain how to create connectionpooling in Tomcat?

9⟩ Explain why the StringBuffer and the wrapper classes defined as final?

10⟩ How to load a class from a remote server?

11⟩ Tell me is it ok to say interfaces, classes are of polymorphism(i.e we can use those for different purposes). if not then why?

12⟩ Suppose I have a rtf file generated out of jasper report.I want to print this file.I tried using Runtime.getRuntime().exec.But, it is not printing.My questions are How to print the file and how do I specify the path of the file for printing?

13⟩ In Java it is possible to define two or more methods within the same class that share the same name, as long as their parameter declarations are differentA) TrueB) False

14⟩ Stacks are controlled through two operations traditionally called _ and ___A) Push and PullB) Push and PopC) Pop and PullD) Pop and Peep

15⟩ Methods declared as static have several restrictions1) They can only call other static methods.2) They must only access static data.3) They cannot refer to this or super in any way Which of these are TRUE?A) 1 and 2B) 1 and 3C) 2 and 3D) 1, 2 and 3

16⟩ In this example class-var = new classname( ); The class name followed by parentheses specifies the _________ for the classA) VariablesB) ConstructorC) ObjectsD) Memory

17⟩ If the method does not return a value, its return type must be voidA) TrueB) False

18⟩ What is the difference between instantiation & initialization?

19⟩ In System.out.println() explain it.My doubt, we call static method with Class name but here what is "out"?

20⟩ What is difference between abstract class and interface?

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Java Classes

Home Java Programing Java Classes

76 Java Classes Questions And Answers

1⟩ A stack stores data using first-in, last-out ordering.A) TrueB) False

2⟩ This can be used inside any method to refer to the current objectA) TrueB) False

3⟩ The type of data returned by a method need not be compatible with the return type specified by the methodA) TrueB) False

4⟩ By using finalization, you can define specific actions that will occur when an object is just about to be reclaimed by the garbage collector.A) TrueB) False

5⟩ What is meant by OO paradigm?

6⟩ Methods that have a return type other than void return a value to the calling routine using the following form of the return statementreturn value;A) TrueB) False

7⟩ The data, or variables, defined within a class are called _______ variablesA) ObjectB) ClassC) InstanceD) None of the above

8⟩ Explain how to create connectionpooling in Tomcat?

9⟩ Explain why the StringBuffer and the wrapper classes defined as final?

10⟩ How to load a class from a remote server?

11⟩ Tell me is it ok to say interfaces, classes are of polymorphism(i.e we can use those for different purposes). if not then why?

12⟩ Suppose I have a rtf file generated out of jasper report.I want to print this file.I tried using Runtime.getRuntime().exec.But, it is not printing.My questions are How to print the file and how do I specify the path of the file for printing?

13⟩ In Java it is possible to define two or more methods within the same class that share the same name, as long as their parameter declarations are differentA) TrueB) False

14⟩ Stacks are controlled through two operations traditionally called ___ and _____A) Push and PullB) Push and PopC) Pop and PullD) Pop and Peep

15⟩ Methods declared as static have several restrictions1) They can only call other static methods.2) They must only access static data.3) They cannot refer to this or super in any way Which of these are TRUE?A) 1 and 2B) 1 and 3C) 2 and 3D) 1, 2 and 3

16⟩ In this example class-var = new classname( ); The class name followed by parentheses specifies the _________ for the classA) VariablesB) ConstructorC) ObjectsD) Memory

17⟩ If the method does not return a value, its return type must be voidA) TrueB) False

18⟩ What is the difference between instantiation & initialization?

19⟩ In System.out.println() explain it.My doubt, we call static method with Class name but here what is "out"?

20⟩ What is difference between abstract class and interface?

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14⟩ Stacks are controlled through two operations traditionally called _ and ___A) Push and PullB) Push and PopC) Pop and PullD) Pop and Peep