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Old 04-24-2004, 02:24 AM   #1
alaios
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can't convert o to FLoat in Java


Plz have a look in this small program and the error that compiler returns

/*
* book.java
*
* Created on 09 April 2004, 01:07
*/

package Package;

/**
*
* @author alaios1
*/
public class book {
String title;
String code;
String last;
String isbn;
Integer quantity;
Float price;
/** Creates a new instance of book */
public book(String mytitle,String mycode,String mylast) {
title=mytitle;mycode=code;mylast=last;
}
public book(String mytitle,String mycode,String mylast,String myisbn,Integer myquantity,Float myprice) {
title=mytitle;code=mycode;last=mylast;isbn=myisbn;quantity=myquantity;price=myprice;
}
public void setTitle(String mytitle) {title=mytitle;}
public void setCode(String mycode) {code=mycode;}
public void setLast(String mylast) {last=mylast;}
public void setIsbn(String myisbn) {isbn=myisbn;}
public void setQuantity(Integer myquantity) {quantity=myquantity;}
public void setPrice(Float myprice) {price=myprice;}

public String getTitle(){return title;}
public String getCode(){return code;}
public String getLast(){return last;}
public String getIsbn(){return isbn;}
public Integer getQuantity(){return quantity;}
public Float getPrice(){return price;}
public Float getValue(Integer discount){return (float)(discount*price);} //Find out what to return here
public void showBook (){} //How i must show the book?
}


/*---Compiler Erros --- */


public Float getValue(Integer discount){return (float)(discount*price);} //Find out what to return here
^
Package/book.java [40:1] incompatible types
found : float
required: java.lang.Float
public Float getValue(Integer discount){return (float)(discount*price);} //Find out what to return here
^
2 errors
Errors compiling book.


As you can see i cannot conver to float.... Why ..? What i must do?
 
Old 04-24-2004, 04:17 AM   #2
Looking_Lost
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try casting thus:

Code:
public Float getValue(Integer discount){
                    return new Float( discount.floatValue() * price.floatValue());
                         }
 
Old 04-24-2004, 07:48 AM   #3
alaios
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Original Poster
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Exclamation oooo

I works...now thx... But why where was my mistake?
Thx
Have a nice day
 
Old 04-24-2004, 09:26 AM   #4
Komakino
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Your mistake was that you defined the return type of getValue as Float (the class java.lang.Float - note the capital F) but you were trying to cast the integer into the java primitive type of float (lower case f). The two aren't the same thing. The Float is an actual class which contains all sorts of methods for dealing with floating point numbers; float is just a basic primitive type to hold a number, it doesn't have any methods: it isn't a class.
 
Old 04-24-2004, 02:10 PM   #5
Looking_Lost
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Yup, as it stands with java you can only cast primitive types, there's an execption, but overall this is the case, Float is a wrapper as mentioned, a class within itself, so java see's it and says, what ya on about, nobody told me you knew each other?

Big hint aswell, Sun havae provied online and downloadable probably the most clearest, accesbile and succint api documentation I have ever see

Last edited by Looking_Lost; 04-24-2004 at 02:20 PM.
 
  


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