Private Variable With Type Of Abstract Class

Oct 10, 2014

I've got an abstract class

public abstract class AbstractClass
{
//stuff
}

And a few classes that inherit from it

public class Class1 extends AbstractClass
{
//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:

public class Test
{
private AbstractClass temp;
public testMethod(){
Class1 anObject = new Class1();
temp = anObject;
}
}

Is this legal? Will temp become a Class1 object?

View Replies


ADVERTISEMENT

Each Class Contain Private Variable

Sep 22, 2014

I'm working on a project that contains multiple classes. Each class contains and must contain only PRIVATE variables. Here's my issue. When my test code calls for a new instance of "StudentClass" as so:

StudentClass studentClass = new StudentClass(offeredClass.getClassIdNumber(),
offeredClass.getClassName(),
offeredClass.getClassroom());

The corresponding constructor won't let me initialize it's variables because they are declared private within another class, as shown here:

StudentClass (float classIdNumber, String className, Classroom room){
this.classIdNumber = classIdNumber;
this.className = className;
this.room = room;
}

When getClassName, getClassroom, and getClassIdNumber are passed to a toString() method elsewhere in my test code. the output is returned just fine. When passed through the StudentClass, I'm getting Null across the board.

View Replies View Related

All Instances Of Same Class Change Each Other Private Variable

May 2, 2015

I have a class named Base and a private variable named _hopcount i have 10 instances of class base i use _hopcount as creteria to some if but other instances edit _hopcount so i want to prevent _hopcount edit by other instances; I want to have private variable which other instances of same class can't modify it.

public class Base extends TypedAtomicActor {
private int _hopcount = 0;
if(_hopcount <= 3) {
some code;
}
public function() {
_hopCount += 1;
}
}

View Replies View Related

Implement Functionalities Of Set Class Using A Private Data Member Of Type ListReferencedBased

Feb 9, 2015

Okay, I am supposed to implement the functionalities of the Set class using a private data member of type ListReferencedBased<E>,how the ListReferenceBased works with what I am trying to accomplish.I am trying to complete Set.java, and I have barely started and much of the code doesn't work. ListReferenceBased was given to me completed.

import java.util.Iterator;
pubic class ListReferenceBased<E> implements ListInterface<E>, Iterable<E>{
/** reference to the first element of the list */
private Node<E> head;
/** number of items in list */
private int numItems;

[code]....

View Replies View Related

Swing/AWT/SWT :: Error At Class Name - Type JTextField Must Implement Inherited Abstract Method

Oct 27, 2014

This code is directly from Swing: I'm using Eclipse and keep getting an error on line 10 saying :

"The type JTextField must implement the inherited abstract method ActionListener.actionPerformed(ActionEvent)."

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

[Code] ......

View Replies View Related

How To Get Access To The Method With A Parameter Of Class Type Variable

Feb 19, 2014

how to get an access to the method with a parameter of class type variable, lets say: public void insert(Record newRecord, int pos)?

View Replies View Related

What Are Benefits Of Using Interface Plus Abstract Class Over Just Abstract Class

Oct 8, 2014

What are the benefits of using an Interface plus an abstract class, over just an abstract class?

View Replies View Related

Encapsulation Hide Private Variable

Sep 10, 2014

As below code showing that you cannot directly access the private variable as i understood,  
 
public class EncapsulationDemo{   private int ssn;  
private String empName;   private int empAge;   //Getter and Setter methods  
public int getEmpSSN(){   return ssn;   }  
public String getEmpName(){   return empName;  

[Code] .....

View Replies View Related

Implement A Set Abstract Data Type Using Singly Linked Lists

May 6, 2015

I am trying to implement product method below which returns the set representing the Cartesian product of the current set and a given set (the Cartesian product contains all ordered pairs (a, b) where a belongs to the current set, and b belongs to the given set). The product should be a ListSet <Tuple<E>> object where each ordered pair is a Tuple element. (I have a Tuple class which implements an ordered tuple)

What am I trying to do in the product method : Make 2 for loop and inside the for loop make an array of <E> then set the 2 elements of the tuple then again set tuple and add it to arrayList. how to set 2 elements of the tuple and set tuple ??

public class ListSet<E> implements Iterable<E>{
SinglyLinkedList<E> sl;
public ListSet(){
sl = new SinglyLinkedList<E>();

[code]....

View Replies View Related

Pass Private Final Class Object To Another Class Constructor

Aug 28, 2014

can we pass private final class object to another class constructor?

View Replies View Related

What Is Abstract Class

Jun 1, 2014

I am just started to learn java and i am facing trouble learning abstract class.

View Replies View Related

How To Convert Input Array Of Type Strings To Class Type

Aug 14, 2014

class Passenger{
String name;
int age;
char gender;
int weight;
public Passenger(){

[Code] ....

This is showing error.....error it gives isthat it cannot change from string type to passenger type......... How to do it??????

View Replies View Related

Constructor In Abstract Class?

Jun 23, 2014

Do we have constructor in abstract class? If we have then what is the use of it?

View Replies View Related

When To Use Interface And Abstract Class

Apr 17, 2014

I know whats the interfaces and abstract class and also know that difference between interface and abstract class,but here my doubt is eventhough abstract class more advantage than the interface,then why should we use interfaces and when?

View Replies View Related

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);
}}

View Replies View Related

How To Convert String Type To Generic Class Type

Mar 22, 2015

I have a String repersentaion of some Object.I want that object convert back into some class type how can I do this?

View Replies View Related

Error - ArrayList Has Private Class

Jan 30, 2015

Java Code:

import java.util.Scanner;
import java.util.ArrayList;
public class Problem1
{
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
ArrayList<String> list = new ArrayList<String>();

[Code] ....

There is an error and says that my ArrayList has private access. I can't figure out how to fix it.

The code runs but when I enter "Quit", the program just stops. The arraylist isn't printed out?

View Replies View Related

Private Variables In Class / Constructor

Jan 7, 2014

When creating a class with a constructor, why does one have to create private variables (attributes) to be used as parameters by the object? The object's parameters will be set to be exactly equal to the private variables (attributes), so what is the point of having the private variables (attributes) Why are both private variables (attributes) and parameters needed when they are set to be equal each other anyway?

View Replies View Related

Accessing Private From Driver Class

May 14, 2015

I came across the below

1) When a variables are declared "Private" How should it be accessed from the driver class ? Sometimes i get an error in driver class saying "your variable is declared Private" why am I getting this error ...

The document says "Private" declared variables should be accessed only through methods. What does that mean.

View Replies View Related

Difference Between Abstract Class And Interface?

May 18, 2011

Difference between Abstract class and Interface??

View Replies View Related

Why Can't Create Object Of Abstract Class

Jul 18, 2014

Why we can't create object of abstract class ,when we can create its constructor?

View Replies View Related

Temporary Object Of Abstract Class

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] .....

View Replies View Related

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 }

View Replies View Related

Create Abstract Auto Class

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

[code]....

View Replies View Related

Can Create Object For Abstract Class

Oct 5, 2014

Animal ob1=new Lion();

Here we create ob1 for Animal class or Lion class.

public abstract class Animal {
public abstract void eat();
public void breathe(){

[Code] ....

View Replies View Related

Writing Constructor In Abstract Class

Feb 4, 2015

Below Code

abstract class A
{
A(int a, int b)
{
}
}

If we can't create objects for abstract class, what is the need of writing constructor???

View Replies View Related







Copyrights 2005-15 www.BigResource.com, All rights reserved