Reference Of Abstract Class

Aug 29, 2014

I passed my abstract class private final reference to another concrete class and I used abstract class reference as parameter to that concrete class constructor and in my main method and null to that parameter then only that program executes correctly...i placing my code below ..if there is any error tell me where is error occurring then i will check my code...i think my code is right but little bit doubt abstract class concept.

{
}
class concept1 extends concept
{
private final concept parent;
public concept1(concept aparent)
{
parent=aparent;
System.out.println(parent);
}
public static void main(String args[])
{
//concept p=new concept1(null);
concept c=new concept1(null);
}}

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Feb 21, 2015

I am under the assumption that In the return statement of getReciprocal() method(of the following code), a temporary Number object is created to hold the result of the calculation.

My question is, Number is an abstract class and we are only able to create reference of an abstract class not an object. But then how a temp Number object is created and returned?

class Gen<T extends Number>{
T ob;
Gen(T ob){
this.ob = ob;
}
Number getReciprocal(){ // Number is abstract class

[Code] .....

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Abstract Class Constructors Are Not Recommended

Aug 28, 2014

in abstract class constructors are not recommended since we don't call it directly ...my doubt is below code is right or wrong...

3public abstract class Concept
4{
5 private String id;
6
7 protected Concept( String anId )
8 {
9 if ( anId == null )
10 {
11 throw new NullPointerException( "id must not be null" );
12 }
13
14 id = anId;
15 }

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Jul 23, 2014

I'm learning about abstract classes and I have to create an abstract auto class with make and price of a car, then two classes with a different type of car, and finally a main to use them. Everything seems to work and when I run it it's fine but I do get an error on the main that I'm not using the local variable buick1 and acura1.I'm curious because, while it runs for me, I want to make sure I'm doing it right and don't know of another way to do the output than this. I've put all four classes but the issue is on the last one (5 and 7).

public abstract class Auto
{
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protected double priceCar;
public Auto(String newMake)
{
makeCar = newMake;

[code]....

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[Code] ....

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Below Code

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Jul 8, 2015

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Oct 10, 2014

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//stuff
}

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//stuff
}
public class Class2 extends AbstractClass
{
//stuff
}

within another class I have a private variable with the type of the Abstract class, and within one of the methods I assign an object to the the variable like this:

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{
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}
}

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Mar 7, 2014

I have a simple classes here one is interface and another one is abstract class when i try to compile them abstract class is givving compilation error.

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[code]....

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Dec 1, 2014

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Q2) i read some site -

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Answer required with detailed information for Q1 and Q2.

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Oct 30, 2014

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private int age = 0;
private String race = "";
private int level = 0;
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[Code] ....

The chain of events right now is:

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import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
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[Code] ......

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class Point{
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Point (int x, int y) {
this.x =x;
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[code]....

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[Code] .....

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