Problems calling a method

[jomcfall97]

hey wondering if anyone can help me with some work im doing
im trying to remove a record from a queue by using a method from a class.

class QueueNode
{
private String document ;
private String owner ;
private int size ;
private QueueNode next ;
private QueueNode previous ;

public QueueNode (String document , String owner , int size)
{
this.document = document ;
this.owner = owner ;
this.size = size ;
next = null ;
previous = null ;
}

public String getDocument()
{
return document ;
}

public String getOwner()
{
return owner ;
}

public int getSize()
{
return size ;
}

public QueueNode getNext()
{
return next ;
}

public QueueNode getPrevious()
{
return previous ;
}

public void setDocument(String document)
{
this.document = document ;
}

public void setOwner(String owner)
{
this.owner = owner ;
}

public void setSize(int size)
{
this.size = size;
}

public void setNext(QueueNode next)
{
this.next = next ;
}

public void setPrevious(QueueNode previous) //this is the part im having trouble with
{
this.previous = previous ;
}
}


class Queue
{
private QueueNode start ;
private QueueNode end ;

public Queue ()
{
start = new QueueNode("","",0) ;
start = null ;
end = new QueueNode("","",0) ;
end = null ;
}


public void add ( String document, String owner, int size )
{
if ( start == null )

{
start = new QueueNode(document,owner,size) ;
end = start ;

}

else
{
QueueNode temp = new QueueNode(document,owner,size) ;
temp.setNext (end) ;
end.setPrevious (temp) ;
end = temp ;
}
}

public boolean isEmpty ()
{
return ( start == null) ;
}

public QueueNode remove ()
{
QueueNode temp = new QueueNode("","",0) ;
if ( start == null )
return null ;

else if ( start.setPrevious == null)
{
temp = start ;
start = null ;
return temp ;
}
else
{
temp = start ;
start = start.setPrevious ;
return temp ;
}
}

public void displayAll ()
{

QueueNode temp = new QueueNode ("","",0) ;
temp = start ;
while ( temp ! = null )
{

System.out.println ( "Document: " + temp.getDocument() ) ;
System.out.println ( "Owner: " + temp.getOwner() ) ;
System.out.println ( "Size: " + temp.getSize() ) ;
temp = temp.setPrevious ;

}
}
}

and these are the errors im getting

Queue.java:47: cannot resolve symbol
symbol : variable setPrevious
location: class QueueNode
else if ( start.setPrevious == null)
^
Queue.java:56: cannot resolve symbol
symbol : variable setPrevious
location: class QueueNode
start = start.setPrevious ;
^
Queue.java:74: cannot resolve symbol
symbol : variable setPrevious
location: class QueueNode
temp = temp.setPrevious ;
^
3 errors

so im not calling setPrevious properly but whats wrong with it?

any help appreciated

thanks

[JosAH]

Your method:

public void setPrevious(QueueNode previous) //this is the part im having trouble with
{
   this.previous = previous ;
}
 

... can only be called like this:

someObject.setPrevious(somePreviousNode);
 

Simply put: you forgot the parentheses and the single parameter.

kind regards,

Jos

[jomcfall97]

hey wondering if anyone can help me with some coursework im doing
im trying to remove a record from a queue by using a method from another class.

 class QueueNode
{
private String document ;
private String owner ;
private int size ;
private QueueNode next ;
private QueueNode previous ;
 
public QueueNode (String document , String owner , int size)
{
this.document = document ;
this.owner = owner ;
this.size = size ;
next = null ;
previous = null ;
}
 
public String getDocument()
{
return document ;
}
 
public String getOwner()
{
return owner ;
}
 
public int getSize()
{
return size ;
}
 
public QueueNode getNext()
{
return next ;
}
 
public QueueNode getPrevious()
{
return previous ;
}
 
public void setDocument(String document)
{
this.document = document ;
}
 
public void setOwner(String owner)
{
this.owner = owner ;
}
 
public void setSize(int size)
{
this.size = size;
}
 
public void setNext(QueueNode next)
{
this.next = next ;
}
 
public void setPrevious(QueueNode previous) 
{
this.previous = previous ;
}
}
 
-----------------------------------------------------------------------
class Queue
{
private QueueNode start ;
private QueueNode end ;
 
public Queue ()
{
start = new QueueNode("","",0) ;
start = null ;
end = new QueueNode("","",0) ;
end = null ;
}
 
 
public void add ( String document, String owner, int size )
{
if ( start == null )
 
{
start = new QueueNode(document,owner,size) ;
end = start ;
 
}
 
else
{
QueueNode temp = new QueueNode(document,owner,size) ;
temp.setNext (end) ;
end.setPrevious (temp) ;
end = temp ;
}
}
 
public boolean isEmpty ()
{
return ( start == null) ;
}
 
public QueueNode remove ()
{
QueueNode temp = new QueueNode("","",0) ;
if ( start == null )
return null ;
 
else if ( start.setPrevious == null)
{
temp = start ;
start = null ;
return temp ;
}
else
{
temp = start ;
start = start.setPrevious ;
return temp ;
}
}
 
public void displayAll ()
{
 
QueueNode temp = new QueueNode ("","",0) ;
temp = start ;
while ( temp ! = null )
{
 
System.out.println ( "Document: " + temp.getDocument() ) ;
System.out.println ( "Owner: " + temp.getOwner() ) ;
System.out.println ( "Size: " + temp.getSize() ) ;
temp = temp.setPrevious ;
 
}
}
}
 

and these are the errors im getting

 Queue.java:47: cannot resolve symbol
symbol : variable setPrevious
location: class QueueNode
else if ( start.setPrevious == null)
^
Queue.java:56: cannot resolve symbol
symbol : variable setPrevious
location: class QueueNode
start = start.setPrevious ;
^
Queue.java:74: cannot resolve symbol
symbol : variable setPrevious
location: class QueueNode
temp = temp.setPrevious ;
^
3 errors
 

what do i have to change?
i did get a reply but it didnt make much sense to me (sorry jos)

thanks

[r035198x]

See how you wrote line 98 above. That's how you should call a method.

[Laharl]

In addition to not actually calling your functions, when setting something equal to the previous entry, you would need to use get, rather than set. This is found in all three errors.

[JosAH]

What is wrong with my answer in your other identical thread?
Don't double post and stick to one thread for one problem.

kind regards,

Jos

[r035198x]

What is wrong with my answer in your other identical thread?
Don't double post and stick to one thread for one problem.

kind regards,

Jos

Argh.
<shakes head>

[RedSon]

jomcfall97,

You are skating on thin ice. Double posting, not using [code] tags, and generally being dense are among your infractions. If Jos's post did not make sense to you then politely ask him to explain.

You need to read the posting guidelines, because the next problem might result in a 5-7 day ban on your account.

-MODERATOR