Help! Constructors not working  
Index ‹ java-programmer
Author Message
Luch
PostPosted: 2005-10-27 13:28:00 Top
java-programmer, Help! Constructors not working I'm doing an assignment for a Java class. Basically, we have to build
constructors for a class, Television, whose attributes are *brand* and
*price*. I have defined the constructors and accessor and mutator
methods in Television.java, and access it via TelevisionClient.java
(code for both is posted below). Both files compile. However when I
run TelevisionClient, it runs through the code, but my constructors,
tv0, which I assign a value in the program, and tv1, which is assigned
through dialog boxes at runtime, are the same value - in other words,
even assigning a value to one, they both have the values that are
passed in through the dialog box. I appreciate any help.

******* Television.java ****************

import java.util.*;
import javax.swing.JOptionPane;
import java.io.*;

public class Television
{
public static String brand;
public static String price;

public Television(String xbrand, String xprice)
{
brand = xbrand;
price = xprice;
}

public static String getBrand()
{
return brand;
}

public static String getPrice()
{
return price;
}

public String toString()
{
String str = "";
str = "Television information:\n"
+ "The brand name is " + this.brand + "\n"
+ "The price is: $" + price;
return str;
}

public boolean equals(Television tvx)
{
if (brand.equals(tvx.brand)
&& price==(tvx.price))
return true;
else
return false;
}
}
******* end Television.java ****************

******* TelevisionClient.java ****************


import javax.swing.JOptionPane;

public class TelevisionClient
{

public static String inputMessage;
public static String outputMessage;
public static String outputMessage2;
public static String outMsg;

Television tv0, tv1;

public void workWithTV( )
{
tv0 = new Television( "RCA", "100.00");

JOptionPane.showMessageDialog( null, tv0.toString( ) );

outputMessage = "This program will list the brand and price of a
television "
+ "based on the values you enter.\n"
+ "It will then compare the values to the default: RCA - $100.00\n";

JOptionPane.showMessageDialog(null, outputMessage,"Television
Attributes",
JOptionPane.PLAIN_MESSAGE);

inputMessage = "Enter the brand of the television:\n\n";

Television.brand = JOptionPane.showInputDialog(inputMessage);

inputMessage = "Enter the price of the television:\n\n";

Television.price = JOptionPane.showInputDialog(inputMessage);

// price = Double.parseDouble(price);

Television tv1 = new Television(Television.brand, Television.price);

outputMessage = tv1.toString();
JOptionPane.showMessageDialog(null, outputMessage,"Television
Attributes",
JOptionPane.PLAIN_MESSAGE);


JOptionPane.showMessageDialog( null, tv0.toString( ) );
JOptionPane.showMessageDialog( null, tv1.toString( ) );


outMsg = "tv0: " + tv0.brand + "/" + tv0.price + "\n"
+ "tv1: " + tv1.brand + "/" + tv1.price + "\n";

JOptionPane.showMessageDialog(null, outMsg,"Television Attributes",
JOptionPane.PLAIN_MESSAGE);

if ( tv1.equals( tv0 ) )
outputMessage2 = "DOES EQUAL";
else
outputMessage2 = "DOES NOT EQUAL";

outputMessage = "The values you entered, brand: " +
Television.getBrand() + " / price: $" + Television.getPrice() + "\n"

JOptionPane.showMessageDialog( null, outputMessage );

if ( tv1 == tv0 )
outputMessage2 = "DOES EQUAL";
else
outputMessage2 = "DOES NOT EQUAL";

outputMessage = "The values you entered, brand: " +
Television.getBrand() + " / price: $" + Television.getPrice() + "\n"

JOptionPane.showMessageDialog( null, outputMessage );
}

public static void main (String[] args)
{
TelevisionClient app = new TelevisionClient( );
app.workWithTV( );
}

}
******* end TelevisionClient.java ****************

 
Roedy Green
PostPosted: 2005-10-27 14:07:00 Top
java-programmer >> Help! Constructors not working On 26 Oct 2005 22:27:48 -0700, "Luch" <email***@***.com> wrote,
quoted or indirectly quoted someone who said :

>public static String brand;
> public static String price;
>
> public Television(String xbrand, String xprice)
> {
> brand = xbrand;
> price = xprice;
> }
Constructors rarely change static variables. You are constructing
facts about a particular television, not about televisions in general.

See http://mindprod.com/jgloss/static.html
http://mindprod.com/jgloss/instance.html
--
Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.
 
 
Index ‹ java-programmer