How to access variable from another class?

Question

gingerfish 0 Light Poster

14 Years Ago

Please help me =(

I'm not native english speaker, therefore some things might be not clear here

I have 2 separate files: Main.java and Open.java

inside main.java there is a GUI and it has a JTextArea) where i want to show text (variable) called from open.java

in Main.java i have (i took out only important codes, real one is much longer):

//textarea
final JTextArea textarea = new JTextArea();
textarea.setEditable(false);
JScrollPane textScrollPane = new JScrollPane(textarea);
textScrollPane.setPreferredSize(new Dimension(800, 100));

//open function
 private void actionPerformedOnOpen(ActionEvent evt, JTextArea textarea) {
javax.swing.JFileChooser chooser = new javax.swing.JFileChooser();
        chooser.addChoosableFileFilter(new FileFilter());
        int option = chooser.showOpenDialog(this);
        if (option == javax.swing.JFileChooser.APPROVE_OPTION) {

String text = new String();
//text = (String)(Open.get(parsedFile));

            java.io.File file = chooser.getSelectedFile();
            if (file == null) return;
            Open readPDBFile = new Open(file.getAbsolutePath());
             textarea.append("Opening: " + file.getName());
             textarea.setText("Testing..."+text);


        }
    }

in Open.java i have a variable which contains some text. i want it to be shown inside the textarea in Main.java like textarea.setText("Testing..."+text); and call variable from Open.java instead of text

i looked all over internet, but couldnt find it helpful.

please please please help meee...

Thank you very much ^^

java text textarea

7 Contributors
10 Replies
3K Views
5 Months Discussion Span
Latest Post 13 Years Ago Latest Post by adams161

All 10 Replies

kevndcks

14 Years Ago

How have you declared your variables in what context, by this i mean either declared as local, instance or class etc?

See this website to understand what i mean by this: http://www.leepoint.net/notes-java/data/variables/45local-inst-class.html

Would need to see more code of your variables and their location more specifically, since the solution to your problem depends on this.

Kind regards.

Edited 14 Years Ago by kevndcks because: n/a

adams161 21 Posting Whiz in Training

14 Years Ago

if you have

class mainclass{

stuff mystuff;
open myopen;

mainclass()
{
mystuff = new stuff();
myopen = new open(mystuff);// we pass a copy of mystuff, its an object so passed by reference.

}
class stuff {

int a;
int b;
int c;
stuff()
{ a=b=c=5;
}
}//end stuff

} // end main class


and open is

class open {
stuff mystuff;

open() { }

open(stuff mystuffpassed)
{
mystuff = mystuffpassed;  // mystuff in open is now linked to stuff
}
}// end class

it has to do with how stuff is passed.

i have a variable like int i=1;

and i pass mystuff(i);

changes to i wont duplicate between teh copies. its pass by value.

pass an object, and you pass by reference so if in one class i do
mystuff.a=6; both copies see this. they share.

Mike

Edited 14 Years Ago by adams161 because: n/a

prisonpassioner 0 Newbie Poster

14 Years Ago

Please help me =(
I'm not native english speaker, therefore some things might be not clear here
I have 2 separate files: Main.java and Open.java
inside main.java there is a GUI and it has a JTextArea) where i want to show text (variable) called from open.java
in Main.java i have (i took out only important codes, real one is much longer):
//textarea
final JTextArea textarea = new JTextArea();
textarea.setEditable(false);
JScrollPane textScrollPane = new JScrollPane(textarea);
textScrollPane.setPreferredSize(new Dimension(800, 100));

//open function
 private void actionPerformedOnOpen(ActionEvent evt, JTextArea textarea) {
javax.swing.JFileChooser chooser = new javax.swing.JFileChooser();
        chooser.addChoosableFileFilter(new FileFilter());
        int option = chooser.showOpenDialog(this);
        if (option == javax.swing.JFileChooser.APPROVE_OPTION) {

String text = new String();
//text = (String)(Open.get(parsedFile));

            java.io.File file = chooser.getSelectedFile();
            if (file == null) return;
            Open readPDBFile = new Open(file.getAbsolutePath());
             textarea.append("Opening: " + file.getName());
             textarea.setText("Testing..."+text);


        }
    }
in Open.java i have a variable which contains some text. i want it to be shown inside the textarea in Main.java like textarea.setText("Testing..."+text); and call variable from Open.java instead of text
i looked all over internet, but couldnt find it helpful.
please please please help meee...
Thank you very much ^^

hi i have gone through u r code its good but not the best u can declare the variable in main instead of another n use it as an global and more often access specifiers are differently used in this n if u want u can look at dynamic billboard

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gingerfish 0 Light Poster · Answer 1 · 2010-01-06T10:35:13+00:00

Oh yes, this is what i have in Open.java :

package pdbviewer;

import org.biojava.bio.structure.io.PDBFileReader;
import org.biojava.bio.structure.Structure;
import org.biojava.bio.structure.GroupIterator;
import org.biojava.bio.structure.Group;
import org.biojava.bio.structure.AminoAcid;
import org.biojava.bio.structure.Chain;
import java.util.Map;

import javax.swing.*;

/**
 *
 * @author ginger
 */
public class Open extends javax.swing.JTextArea{


    public Open(String filename) {



 PDBFileReader pdbreader = new PDBFileReader();

 
 pdbreader.setParseSecStruc(true);

 pdbreader.setAlignSeqRes(true);

 pdbreader.setParseCAOnly(false);

 pdbreader.setAutoFetch(false);



 try{
     Structure struc = pdbreader.getStructure(filename); //i want this

     System.out.println(struc);

     GroupIterator gi = new GroupIterator(struc);

     while (gi.hasNext()){

           Group g = (Group) gi.next();//this

           if ( g instanceof AminoAcid ){
               AminoAcid aa = (AminoAcid)g;
               Map sec = aa.getSecStruc();//and this to be viewed in the textarea in Main.java
               Chain  c = g.getParent();
               System.out.println(c.getName() + " " + g + " " + sec);

        
           }

     }

 } catch (Exception e) {
     e.printStackTrace();
 }



    }
}

There are some texts are being printed out in console, i want them to be called into the textarea in Main.java

Thanks a lot ^^

jaka.ramdani -1 Newbie Poster · Answer 2 · 2010-01-07T10:02:49+00:00

You can use Observer-Pattern, i made a quite simple sample which will printing current datetime to console and within relatively same time append same current datetime to an JTextArea, scheduled every 5 seconds, infinitely (till program closed).

/*
 * MyFrame.java
 *
 * Created on Jan 7, 2010, 10:40:13 AM
 */
import java.util.Observable;
import java.util.Observer;

/**
 *
 * @author jaka
 */
public class MyFrame extends javax.swing.JFrame implements Observer {

    /** Creates new form MyFrame */
    public MyFrame() {
        initComponents();
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        jScrollPane1 = new javax.swing.JScrollPane();
        outputArea = new javax.swing.JTextArea();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jLabel1.setText(org.openide.util.NbBundle.getMessage(MyFrame.class, "MyFrame.jLabel1.text")); // NOI18N

        outputArea.setColumns(20);
        outputArea.setRows(5);
        jScrollPane1.setViewportView(outputArea);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 384, Short.MAX_VALUE)
                    .addComponent(jLabel1))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel1)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 268, Short.MAX_VALUE)
                .addContainerGap())
        );

        pack();
    }// </editor-fold>

    public void update(Observable o, Object obj) {
        String text = (String) obj;
        outputArea.append(text);
    }

    /**
    * @param args the command line arguments
    */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new MyFrame().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify
    private javax.swing.JLabel jLabel1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea outputArea;
    // End of variables declaration


}

and the Main.java

import java.util.Calendar;
import java.util.Date;
import java.util.Observable;
import java.util.Timer;
import java.util.TimerTask;

/**
 *
 * @author jaka
 */
public class Main extends Observable {

    private Timer timer = new Timer();
    private String currentTimeString = null;

    public Main() {
    }

    public void startInfiniteTimer() {
        TimerTask task = new TimerTask() {

            @Override
            public void run() {
                Date current = Calendar.getInstance().getTime();
                currentTimeString = "Current date: " + current.toString() + "\n";
                System.out.print(currentTimeString);
                setChanged();
                notifyObservers(currentTimeString);
            }
        };
        timer.schedule(task, 0, 5000); //every 5 seconds
    }

    public static void main(String[] args) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                Main main = new Main();
                MyFrame frame = new MyFrame();
                frame.setVisible(true);
                main.addObserver(frame);
                main.startInfiniteTimer();
            }
        });
    }

}

See how easy it is, just make the Class/Object you want to observe extends Observable, and another Class as it's observer.

p.s:
Sorry it the MyFrame.java is too long, i am using Netbeans GUI builder to build the frame.

gingerfish 0 Light Poster · Answer 3 · 2010-01-08T19:24:24+00:00

Thanks everyone, i figured it out thanks to your help ^^

adams161 21 Posting Whiz in Training · Answer 4 · 2010-01-09T02:57:41+00:00

adams161 21 Posting Whiz in Training

14 Years Ago

glad we were of help. maybe mark it as solved?

Mike

Ezzaral 2,714 Posting Sage Team Colleague Featured Poster · Answer 5 · 2010-01-09T03:44:49+00:00

hi i have gone through u r code its good but not the best u can declare the variable in main instead of another n use it as an global and more often access specifiers are differently used in this n if u want u can look at dynamic billboard

No, just no. Suggesting the use of a "global variable" from main.java is probably the worst way possible to go about it. And you need to read this as well: http://www.daniweb.com/forums/faq.php?faq=daniweb_policies#faq_keep_it_clean

All that is needed is a public method on the "open" class that returns the data you want to display: open.getTheText()

kirthiga 0 Newbie Poster · Answer 6 · 2010-06-29T09:25:13+00:00

hi please say the output for this pseudo
employee
{
int empid;
}
class A
{
public static void main(String args[])
{
Hashset s=new Hashset();
for(int i=0;i<10;i++)
{
for(intj=0;j<10;j++)
emp(1);
s.add(empid);
}
}
s.o.p("count"+empid);

adams161 21 Posting Whiz in Training · Answer 7 · 2010-06-29T10:24:43+00:00

This topic is 6 months old and maybe you meant to start a new post. I think its at the bottom of the forum page, start new post/topic.

Mike

How to access variable from another class?

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