non-static method problem: how to access non-static method from another .java file?

[xirowei]

i now learning Object Oriented Programming but stuck. Need help. Below is the code.

 PanelOption.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
 
public class PanelOption extends JPanel
{
    //some code
 
    public PanelOption()
    {
        createOptionGUI();
    }
 
    public void createOptionGUI()
    {                        
        //some code
    }
 
    public class ButtonListener implements ActionListener
    {
        public void actionPerformed(ActionEvent e) 
        {            
            if (e.getSource()==jbtnEnter)
            {
                PanelQuestion.Question01(); // <= i wan to access to this void method but fail! How to solve?
 
            } 
        }    
    }
}
 
//======================================================================    
 
PanelQuestion.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
 
public class PanelQuestion extends JPanel
{
    //some code
 
    public PanelQuestion()
    {
        createQuestionGUI();
    }
 
    public void createQuestionGUI()
    {
        //some code
    }
 
    public void Question01()
    {
        //some code  (this is the void method that i want to invoke by PanelOption.java)
    }
}

[epots9]

i now learning Object Oriented Programming but stuck. Need help. Below is the code.


PanelOption.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class PanelOption extends JPanel
{
//some code

public PanelOption()
{
createOptionGUI();
}

public void createOptionGUI()
{
//some code
}

public class ButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
if (e.getSource()==jbtnEnter)
{
PanelQuestion.Question01(); // <= i wan to access to this void method but fail! How to solve?

}
}
}
}

//================================================== ====================

PanelQuestion.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class PanelQuestion extends JPanel
{
//some code

public PanelQuestion()
{
createQuestionGUI();
}

public void createQuestionGUI()
{
//some code
}

public void Question01()
{
//some code (this is the void method that i want to invoke by PanelOption.java)
}
}

Hi xirowei, welcome to TSDN,

create an object of type PanelQuestion

PanelQuestion pq = new PanelQuestion();
 

then call the the method

pq.Question01();
 

all non-static methods must be perfixed with an object.

good luck

[JosAH]

Consider the following scenario: my name is Jos, I'm an instantiation of the
class SillyPerson. You can tell me things:

public void tell(String message) {
...
}
 

If you want to tell me something you have to do this:

SillyPerson jos= new SillyPerson();
jos.tell("you are silly");
 

and the message would be sent to me.

You can't just do this:

SillyPerson.tell("you are silly");
 

because you are talking to an instance of the class SillyPerson (e.g. me) not
to the class, the blueprint of all silly persons. In other words: you need at least
an instantiation to talk to.

kind regards,

Jos

[r035198x]

Consider the following scenario: my name is Jos, I'm an instantiation of the
class SillyPerson. You can tell me things:

public void tell(String message) {
...
}
 

If you want to tell me something you have to do this:

SillyPerson jos= new SillyPerson();
jos.tell("you are silly");
 

and the message would be sent to me.

You can't just do this:

SillyPerson.tell("you are silly");
 

because you are talking to an instance of the class SillyPerson (e.g. me) not
to the class, the blueprint of all silly persons. In other words: you need at least
an instantiation to talk to.

kind regards,

Jos

Indeed welcome to TSDN. As you can see we have all sorts of people here. Now you see how your code looks under code tags? So next time you post code just wrap it inside code=java tags. the tags go inside square brackets []

[JosAH]

As you can see we have all sorts of people here.

No we don't:

Collection<SillyPerson> TSDN= new ArrayList<SillyPerson>();
 

kind regards,

Jos ;-)

[xirowei]

epots9 thank you very much. You guide is really simple and easy to understand. Now it solve my problem of the non-static problem.

[r035198x]

epots9 thank you very much. You guide is really simple and easy to understand. Now it solve my problem of the non-static problem.

Well the SillyPerson example really looked good too. It told quite a lot of true things which you would have done good to notice.

[epots9]

i won't disagree with u there r035198x, but still

[JosAH]

:-)

kind regards,

Jos

[r035198x]

:-)

kind regards,

Jos

TSDNAdmin nonSillyPerson = TSDN.getAdmin();
for(SillyPerson silly : TSDN) {
     if(silly instanceOf Jos || silly instanceOf epots9) {
          nonSillyPerson.ban(silly);
          System.gc(); 
     }
}

[epots9]

TSDNAdmin nonSillyPerson = TSDN.getAdmin();
for(SillyPerson silly : TSDN) {
     if(silly instanceOf Jos || silly instanceOf epots9) {
          nonSillyPerson.ban(silly);
          System.gc(); 
     }
}

lol, that was good

lmao

[JosAH]

TSDNAdmin nonSillyPerson = TSDN.getAdmin();
for(SillyPerson silly : TSDN) {
     if(silly instanceOf Jos || silly instanceOf epots9) {
          nonSillyPerson.ban(silly);
          System.gc(); 
     }
}

Ha! Code war!

TSDNAdmin nonSillyPerson = TSDN.getAdmin();
for(SillyPerson silly : TSDN) {
     if(silly instanceOf Jos || silly instanceOf epots9) {
          nonSillyPerson.ban(silly= null);
          System.gc(); 
     }
}

kind regards,

Jos ;-)

[r035198x]

Ha! Code war!

TSDNAdmin nonSillyPerson = TSDN.getAdmin();
for(SillyPerson silly : TSDN) {
     if(silly instanceOf Jos || silly instanceOf epots9) {
          nonSillyPerson.ban(silly= null);
          System.gc(); 
     }
}

kind regards,

Jos ;-)

public boolean ban (SillyPerson silly) {
     if(silly == null) {
         for(SillyPerson silly : TSDN) {
                  if(silly instanceOf Jos || silly instanceOf epots9) {
                   silly.defenestrate();
             }
         }
     }
     else {
          silly.defenestrate();
     }
               System.gc(); 
}
 

[JosAH]

public boolean ban (SillyPerson silly) {
     if(silly == null) {
         for(SillyPerson silly : TSDN) {
                  if(silly instanceOf Jos || silly instanceOf epots9) {
                   silly.defenestrate();
             }
         }
     }
     else {
          silly.defenestrate();
     }
               System.gc(); 
}
 

Ha! simple stuff:

public boolean ban (SillyPerson silly) {
     if(silly == null && silly != null) {
         for(SillyPerson silly : TSDN) {
                  if(silly instanceOf Jos || silly instanceOf epots9) {
                   silly.defenestrate();
             }
         }
     }
     else {
          (silly= r035198x).defenestrate();
     }
               System.gc(); 
}
 

kind regards,

Jos ;-)

[r035198x]

Ha! simple stuff:

public boolean ban (SillyPerson silly) {
     if(silly == null && silly != null) {
         for(SillyPerson silly : TSDN) {
                  if(silly instanceOf Jos || silly instanceOf epots9) {
                   silly.defenestrate();
             }
         }
     }
     else {
          (silly= r035198x).defenestrate();
     }
               System.gc(); 
}
 

kind regards,

Jos ;-)

Incompatible types: found TSDNAdminNonSillyPerson required, SillyPerson (Jos)

[JosAH]

Incompatible types: found TSDNAdminNonSillyPerson required, SillyPerson (Jos)

Duh:

public interface Defenestratable {
   public void defenestrate();
}
...
public class TSDNAdminNonSillyPerson implements Defenestratable {
   ...
}
 

kind regards,

Jos ;-)

[r035198x]

Duh:

public interface Defenestratable {
   public void defenestrate();
}
...
public class TSDNAdminNonSillyPerson implements Defenestratable {
   ...
}
 

kind regards,

Jos ;-)

Argh, alright I give up. I'm cooked. There should not be allowed a reasonable implemention of the defenestrate method.
Next time I'll choose the pink axe first ...