Calling a method in another JVM instance

I know you can use RMI to call the methods from classes across the network, but if the class is on the same machine, just in another JVM instance, is there a way to bypass the network layer and have the JVMs communicate directly with each other?

Its not so much the overhead, as having the
flexibility, to not have to modify firewall rules
which disallow loop back traffic and most other non
http (port 80) traffic if the production server is
set up that way.You're coding to interfaces anyway, have a factory return either an RMI object which does the actual RMI work, or just a vanilla one if you're just running locally. As far as I know, there isn't a way to entirely circumvent the socket layer with RMI. Anyone know any different?

Similar Messages

How do you call a method from another class without extending as a parent?

How do you call a method from another class without extending it as a parent? Is this possible?

Why don't you just create an instance of the class?
Car c = new Car();
c.drive("fast");The drive method is in the car class, but as long as the method is public, you can use it anywhere.
Is that what you were asking or am I totally misunderstanding your question?
Jen

Calling a method from another file

This is pretty basic stuff but i can't seem to get it right. I am calling a method from another file. The other file IS located in the same folder BUT when i compile i get errors
"cannot find symbol" <===referring to limit and sieve i believe.
The method name is "sieve" the file name is "PrimeSieve2008" and "limit" is the variable in brackets in the real method.
     public static void main (String [] args) {
final int [] PRIMES;
int sieve = PrimeSieve2008.sieve(limit);
     PRIMES = sieve(getValidInt());
          for (int j = 0; j<PRIMES.length; j++) {
               System.out.println("Prime[" + j + "] = " + PRIMES[j]);
Is "int sieve = PrimeSieve2008.sieve(limit)" the wrong way to call a file?
Thanks a million,
Alex
Edited by: Simplistic2099 on Apr 3, 2008 7:47 PM
Edited by: Simplistic2099 on Apr 3, 2008 7:49 PM

Simplistic2099 wrote:
the other method runs fine:
"public static int[] sieve(final int limit){
int candidate; // possible prime
int count; // no. of primes found
boolean[] mayBePrime = new boolean[limit+1];
// remaining possibilities
final int[] PRIMES; // array to return
// initialize mayBePrime
for ( int j = 0 ; j <= limit ; j++ ) {
mayBePrime[j] = true;
mayBePrime[0] = mayBePrime[1] = false;
// apply sieve, and count primes
candidate = 2;
count = 0;
while ( candidate <= limit ) {
if ( mayBePrime[candidate] ) {
count++;
for ( int j = 2 * candidate ; j <= limit ; j += candidate ) {
mayBePrime[j] = false;
} // end for
} // end if
candidate++;
} // end while
// fill up new array with the primes found
PRIMES = new int[count];
count = 0;
for (int j = 2 ; j <= limit ; j++ ) {
if ( mayBePrime[j] ) {
PRIMES[count] = j;
count++;
} // end if
} // for
return PRIMES;
} // sieve
I really am clueless here.in this one you are passing in limit.
in the other one you are getting limit from somewhere outside of main.

Calling a method from another class... that requires variables?

I'm calling a method from another class to change the date (its a date object) in another class.
I keep getting the error 'setDate(int,int,int) in Date cannot be applied to ()'
My code is:
public int changeDate()
cycleDate.setDate();
}I'm guessing I need to pass 3 parameters (day, month, year), but I'm not sure how! I have tried, but then I get errors such as ')' expected?
Any ideas! :D

f1d wrote:
I'm calling a method from another class to change the date (its a date object) in another class.
I keep getting the error 'setDate(int,int,int) in Date cannot be applied to ()'
My code is:
public int changeDate()
cycleDate.setDate();
}I'm guessing I need to pass 3 parameters (day, month, year), seems that way from the error you posted
but I'm not sure how!
setDate(16, 6, 2008);
I have tried, but then I get errors such as ')' expected?
Any ideas! :Dyou need to post your code if you're getting specific errors like that.
but typically ')' expected means just that, you have too many or not enough parenthesis (or in the wrong place, etc.)
i.e. syntax error

Can't add list element when calling a method from another class

I am trying to call a method in another class, which contains code listmodel.addElement("text"); to add an element into a list component made in that class.
I've put in System.out.println("passed"); in the method just to make sure if the method was being called properly and it displays normally.
I can change variables in the other class by calling the method with no problem. The only thing I can't do is get listmodel.addElement("text"); to add a new element in the list component by doing it this way.
I've called that method within it's class and it added the element with no problem. Does Java have limitations about what kind of code it can run from other classes? And if that's the case I'd really like to know just why.

There were no errors, just the element doesnt get added to the list by doing it this way
class showpanel extends JPanel implements ActionListener, MouseMotionListener {
       framepanel fp = new framepanel();
       --omitted--
     public void actionPerformed(ActionEvent e){
              if(e.getSource() == button1){
                   fp.addLayer();
/*is in a different class file*/
class framepanel extends JPanel implements ActionListener{
        --omitted--
     public void addLayer(){
          listmodel.addElement("Layer"+numLayer);
          numLayer++;
}

Help on Calling a method from another class

how can i call a method from another class.
Class A has 3 methods
i just want to call only one of these 3 methods into my another class.
How can I do that.

When i am trying this
A a=new A;
Its calling all the methods from class A. I just want
to call a specfic method.How can it be done?When i am trying this
A a=new A();
Its calling all the methods from class A. I just want to call a specfic method.How can it be done?

Can we call main method in another class?

Hi...
can we call main method in another class?
If no, please tell me the exact reason why can't we call that....

ok
can u give that code for me?
class A {
public static void main(String [] args){
System.out.println("In A");
class B {
public static void main(String [] args){
A.main(null);
}

How to call a method of another class ?

Hello,
I�d like to know how to call a method of another class. I have to classes (class 1 and class 2), class 1 instantiates an object of class 2 and executes the rest of the method. Later, class 1 has to call a method of class 2, sending a message to do something in the object... Does anybody know how to do that ? Do I have to use interface ? Could you please help me ?
Thanks.
Bruno.

Hi Schiller,
The codes are the following:
COMECO
import javax.swing.UIManager;
import java.awt.*;
import java.net.*;
import java.io.*;
import java.awt.event.*;
import javax.swing.*;
//Main method
class comeco {
public static void main(String[] args) {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
catch(Exception e) {
AGORA testeagora=new AGORA();
// Code for socket
int port;
     ServerSocket server_socket;
     BufferedReader input;
     try {
     port = Integer.parseInt(args[0]);
     catch (Exception e) {
     System.out.println("comeco ---> port = 1500 (default)");
     port = 1500;
     try {
     server_socket = new ServerSocket(port);
     System.out.println("comeco ---> Server waiting for client on port " +
               server_socket.getLocalPort());
     // server infinite loop
     while(true) {
          Socket socket = server_socket.accept();
          System.out.println("comeco ---> New connection accepted " +
                    socket.getInetAddress() +
                    ":" + socket.getPort());
          input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
          // print received data
          try {
          while(true) {
               String message = input.readLine();
               if (message==null) break;
               System.out.println("comeco ---> " + message);
testeagora.teste(message);
          catch (IOException e) {
          System.out.println(e);
          // connection closed by client
          try {
          socket.close();
          System.out.println("Connection closed by client");
          catch (IOException e) {
          System.out.println(e);
     catch (IOException e) {
     System.out.println(e);
AGORA
import javax.swing.UIManager;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;
import javax.swing.*;
import java.net.*;
//public class AGORA {
public class AGORA {
boolean packFrame = false;
//Construct the application
public AGORA() {
try {
Main frame = new Main();
System.out.println("agora ---> Criou o frame");
//Validate frames that have preset sizes
//Pack frames that have useful preferred size info, e.g. from their layout
if (packFrame)
frame.pack();
else
frame.validate();
//Center the window
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
Dimension frameSize = frame.getSize();
if (frameSize.height > screenSize.height)
frameSize.height = screenSize.height;
if (frameSize.width > screenSize.width)
frameSize.width = screenSize.width;
frame.setLocation((screenSize.width - frameSize.width) / 2, (screenSize.height - frameSize.height) / 2);
frame.setVisible(true);
catch(Exception e)
{ System.out.println("agora ---> " +e);
// Tem que criar a THREAD e ver se funciona
public void remontar (final String msg) {
try {
               System.out.println("agora ---> Passou pelo Runnable");
System.out.println("agora --> Mensagem que veio do comeco para agora: "+ msg);
Main.acao(msg);
catch(Exception x) {
x.printStackTrace();
MAIN
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import com.borland.jbcl.layout.*;
import javax.swing.border.*;
import java.net.*;
import java.io.*;
public class Main extends JFrame {
// ALL THE CODE OF THE INTERFACE
//Construct the frame
public Main() {
enableEvents(AWTEvent.WINDOW_EVENT_MASK);
try {
jbInit();
catch(Exception e) {
e.printStackTrace();
public void acao() {
// C�digo para mudar a interface
Runnable setTextRun=new Runnable() {
public void run() {
try {
               System.out.println("main ---> Passou pelo Runnable");
TStatus.setText("main ---> Funcionou");
catch(Exception x) {
x.printStackTrace();
System.out.println("main ---> About to invokelater");
SwingUtilities.invokeLater(setTextRun);
System.out.println("main ---> Back from invokelater");
// Aqui vai entrar o m�todo para ouvir as portas sockets.
// Ele deve ouvir e caso haja alguma nova mensagem, trat�-la para
// alterar as vari�veis e redesenhar os pain�is
// Al�m disso, o bot�o de refresh deve aparecer ativo em vermelho
//Component initialization
private void jbInit() throws Exception {
// Initialize the interface
//Setting | Host action performed
public void SetHost_actionPerformed(ActionEvent e) {
     int port;
     ServerSocket server_socket;
     BufferedReader input;
System.out.println("main ---> port = 1500 (default)");
     port = 1500;
     try {
     server_socket = new ServerSocket(port);
     System.out.println("main ---> Server waiting for client on port " +
               server_socket.getLocalPort());
     // server infinite loop
while(true) {
          Socket socket = server_socket.accept();
          System.out.println("main ---> New connection accepted " +
                    socket.getInetAddress() +
                    ":" + socket.getPort());
          input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String espaco=new String(": ");
     JLabel teste2=new JLabel(new ImageIcon("host.gif"));
          PHost.add(teste2);
System.out.println("main ---> Adicionou host na interface");
          repaint();
System.out.println("main ---> Redesenhou a interface");
          setVisible(true);
          // print received data
          try {
          while(true) {
               String message = input.readLine();
               if (message==null) break;
               System.out.println("main ---> " + message);
          catch (IOException e2) {
          System.out.println(e2);
          // connection closed by client
          try {
          socket.close();
          System.out.println("main ---> Connection closed by client");
          catch (IOException e3) {
          System.out.println(e3);
     catch (IOException e1) {
     System.out.println(e1);
public void OutHost_actionPerformed(ActionEvent e) {
          repaint();
          setVisible(true);
//Help | About action performed
public void helpAbout_actionPerformed(ActionEvent e) {
Main_AboutBox dlg = new Main_AboutBox(this);
Dimension dlgSize = dlg.getPreferredSize();
Dimension frmSize = getSize();
Point loc = getLocation();
dlg.setLocation((frmSize.width - dlgSize.width) / 2 + loc.x, (frmSize.height - dlgSize.height) / 2 + loc.y);
dlg.setModal(true);
dlg.show();
//Overridden so we can exit on System Close
protected void processWindowEvent(WindowEvent e) {
super.processWindowEvent(e);
if(e.getID() == WindowEvent.WINDOW_CLOSING) {
fileExit_actionPerformed(null);
public void result(final String msg) {
// C�digo para mudar a interface
Runnable setTextRun=new Runnable() {
public void run() {
try {
               System.out.println("main ---> Chamou o m�todo result para mudar a interface");
System.out.println("main --> Mensagem que veio do agora para main: "+ msg);
TStatus.setText(msg);
catch(Exception x) {
x.printStackTrace();
System.out.println("main --> About to invokelater");
SwingUtilities.invokeLater(setTextRun);
System.out.println("main --> Back from invokelater");
[]�s.

How to call a method from another class

I have a problem were i have to call a method from another class. What is the command line that i have to use. Thanks.

Here's one I wipped up in 10 minutes... Cool!
package forums;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import krc.utilz.io.Filez;
import java.io.FileNotFoundException;
class FileDisplayer extends JFrame
private static final long serialVersionUID = 0L;
FileDisplayer(String filename) {
    super(filename);
    this.setDefaultCloseOperation(EXIT_ON_CLOSE);
    this.setSize(600, 800);
    JTextArea text = new JTextArea();
    try {
      text.setText(Filez.read(filename));
    } catch (FileNotFoundException e) {
      text.setText(e.toString());
    this.add(text);
public static void main(String args[]) {
    final String filename = (args.length>0 ? args[0] : "C:/Java/home/src/forums/FileDisplayer.java");
    try {
      java.awt.EventQueue.invokeLater(
        new Runnable() {
          public void run() {
            new FileDisplayer(filename).setVisible(true);
    } catch (Exception e) {
      e.printStackTrace();
Filez.read
   * reads the given file into one big string
   * @param String filename - the name of the file to read
   * @return the contents filename
public static String read(String filename) throws FileNotFoundException {
    return Filez.read(new FileReader(filename));
   * Reads the contents of the given reader into one big string, and closes the reader.
   * @param java.io.Reader reader - a subclass of Reader to read from.
   * @return the whole contents of the given reader.
public static String read(Reader in) {
    try {
      StringBuffer out = new StringBuffer();
      try {
        char[] bfr = new char[BFRSIZE];
        int n = 0;
        while( (n=in.read(bfr,0,BFRSIZE)) > 0 ) {
          out.append(bfr,0,n);
      } finally {
        if(in!=null)in.close();
      return out.toString();
    } catch (IOException e) {
      throw new RuntimeIOException(e.getMessage(), e);
}Edited by: corlettk on Dec 16, 2007 1:01 PM - dang [code [/tags][

Call method from another class instance

Forgive me if I don't make sense, I'm relatively new to Java and still not up on all the lingo.
So here's what I want to do... This is probably easier explained with code:
ParentClass.java
public class ParentClass {
     public static void main(String[] args)
          ChildClass1 child1 = new ChildClass1();
          ChildClass2 child2 = new ChildClass2();
          System.out.println("ParentClass");
          System.out.println(child1.getText());
          System.out.println(child2.getText());
ChildClass1.javapublic class ChildClass1 {
     private String text = "ChildClass1";
     public ChildClass1()
          System.out.println("ChildClass1 Constructor");
     public String getText()
     { return text; }
}ChildClass2.java is identical to ChildClass1, except the 1's replaced with 2's etc.
I need to be able to call getText() in ChildClass1 from ChildClass2, and eventually methods in the ParentClass class.
As I understand, if I make the ChildClass's extend the ParentClass, every new instance of the ChildClass will create a new instance of the ParentClass. What I need though, is one instance of ParentClass with it's eventual variables etc. set, and then have the two classes defined within, able to talk to each other and the methods in the ParentClass.
How does one go about doing this? Does that even make sense?
Thanks, Savage

You may need to read thru the information provided on this page to understand how to create objects: http://java.sun.com/docs/books/tutorial/java/data/objectcreation.html
I'd also suggest you read the tutorial available at: http://java.sun.com/docs/books/tutorial/java/index.html
Regarding how you call a method belonging to another class you could do it in the foll. ways depending on whether the method is static or not - a static method may be called using the class name followed by a dot and the static method name while a non-static method would require you to create an instance of the class and then use that instance name followed by a dot and the method name. All said and done i'd still suggest you read thru the complete Java programming tutorial to get a good grounding on all these concepts and fundamentals of the language if you are looking to master the technology.
Thanks
John Morrison

Calling a method from another class. Please Help!!

Here is my full program. Like I said in my last post. I am having trouble calling the baseMakesError1 method. This method is called in the subcallsbase1 method. Also, it would be of great help if you could look for any other errors with with my program. Thank you so much. I really appreciate it.
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
public class ThomasR11
String sy;
public static void main(String[] args)
System.out.println("(main): Ryan Thomas, file ThomasR11: Exceptions");
SubRT obj3;
SubRT obj4;
String sX;
String x;
String s;
String sY;
try
ThomasR11 obj1=new ThomasR11();
catch(NullPointerException NPE)
System.err.println("Null Pointer Exception");
ThomasR11 obj2=new ThomasR11("Hello");
System.out.println("This is the last statement in main");
public ThomasR11()
SubRT obj3= new SubRT();
obj3.subCallsBase1();
public ThomasR11(String sY)
throws FileNotFoundException
SubRT obj4= new SubRT();
obj4.subError2();
obj4.subError3(sY);
private static class BaseRT
public BaseRT()
System.out.println("In BaseRT constructor= " + this);
public void baseMakesError1(int value0)
System.out.println("In BaseRT constructor, about to throw exception");
if (value0==0)
throw new NullPointerException("NullPointerException");
private class SubRT extends BaseRT
SubRT subNull;
public SubRT()
System.out.println("In SubRT constructor before call to aMakes an error= " +
"\n SubRT constructor= " + this);
public void subCallsBase1()
try
System.out.println("Calling the method baseMakeserror1");
baseMakesError1(subNull);<---------------------This is where I am getting the error it says "ThomasR11.java [79:1] baseMakesError1(int) in ThomasR11.BaseRT cannot be applied to (ThomasR11.SubRT)"
catch(NumberFormatException NFE)
System.err.println("\nNumber Format Exception");
catch (NullPointerException NPE)
System.err.println(NPE.getMessage() + "\n");
System.err.println(NPE.toString() + "\n");
throw NPE;
public void subError2()
try
BufferedReader in = new BufferedReader( new FileReader( "c:/xx/xx.xx" ) );
catch(NullPointerException NPE)
System.out.println("Null Pointer Exception");
catch (FileNotFoundException FNFE)
System.err.println("FileNotFoundException");
public void subError3( String sX)
try
System.out.println("Hello");
System.out.println (sX.length());
catch(NullPointerException NPE)
System.err.println("Null Pointer Exception");

"ThomasR11.java [79:1] baseMakesError1(int) in ThomasR11.BaseRT cannot be applied to (ThomasR11.SubRT)"
...this error is telling out that you wrote baseMakesError1 to accept an "int" as an argument, and you are trying to pass it an instance of the ThomasR11.SubRT class. You either have to change baseMakesError1 to accept a SubRT as an argument, or change your call to pass an integer.

Calling a method of another Object

I have 3 panels, panelMain, panelA and panelB
panelMain is the "main" panel which holds panelA and panelB.
When a button is clicked in panelB, I wish to call up the a method in panelA, but I get the error
"non-static method cannot be referenced froma static context"
What might be the problem?

It's normal, to call a method of an instance, you must have a handler on the instance. In your case, panelB must have a handler ( a kind of reference if you want) on panelA (i.e. panelB must know the instance of panelA to call a method of panelA).
For example :
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class PanelB extends JPanel {
     public PanelA panelA; // to keep the instance of panelA needed to call the methods of panelA
     JLabel messageLabel;
     public PanelB() {
          super();// optional
          JLabel label = new JLabel("This is the panelB");
          add(label);
          JButton button = new JButton("Call panelA method");
          button.addActionListener(new ActionListener() {
               public void actionPerformed(ActionEvent e) {
                    panelA.showMessage(); // call a method of panelA
          add(button);
          messageLabel = new JLabel("");
          add(messageLabel);
     public void setPanelA(PanelA p) { // initialize panelA with the required instance
          panelA = p;
     public void showMessage() {
          messageLabel.setText("Message from panelA");
class PanelA extends JPanel {
     public PanelB panelB; // to keep the instance of panelB needed to call the methods of panelB
     JLabel messageLabel;
     public PanelA() {
          super();// optional
          JLabel label = new JLabel("This is the panelA");
          add(label);
          JButton button = new JButton("Call panelB method");
          button.addActionListener(new ActionListener() {
               public void actionPerformed(ActionEvent e) {
                    panelB.showMessage(); // call a method of panelB
          add(button);
          messageLabel = new JLabel("");
          add(messageLabel);
     public void setPanelB(PanelB p) { // initialize panelA with the required instance
          panelB = p;
     public void showMessage() {
          messageLabel.setText("Message from panelB");
public class MainPanel extends JPanel {
     public MainPanel() {
          super(); // optional
          setLayout(new GridLayout(1,2,0,0));
          PanelA pa = new PanelA();
          add(pa);
          PanelB pb = new PanelB();
          add(pb);
          pa.setPanelB(pb);
          pb.setPanelA(pa);
     public static void main(String[] arg) {
          JFrame f = new JFrame("My Frame");
          f.getContentPane().add(new MainPanel());
          f.setBounds(100,100,300,300);
          f.setVisible(true);
}I hope this helps,
Denis

Calling repaint method from another class

My question in a very simple form :
how do I call repaint mathod from another class.
e.g: Let's say class "A.java" is a JFrame .
Class "B.java" is a JPanel which is added to the JFrame above.
Class "C.java" is a JDialog containing some JButtons.
How do I call the repaint method from the class "C.java".
Thank you in advance!!

My question in a very simple form :
how do I call repaint mathod from another class.
e.g: Let's say class "A.java" is a JFrame .
Class "B.java" is a JPanel which is added to the JFrame above.
Class "C.java" is a JDialog containing some JButtons.
How do I call the repaint method from the class "C.java".
Thank you in advance!!

Changing an object by calling a method in another class that returns nothin

How can a method like for example Arrays.sort(Object[] a) work? The method has a return statement void, so how come the array passed into the method "magically" end up as being sorted when we look at it in another class after having called this method?

jverd wrote:
sunfun99 wrote:
Since references really are more like addresses, jverd's adress-on-pieces-of-paper analogy is the best, but certainly not because the addresses on the pieces of paper are copies of the address (they aren't). We may just be splitting ever finer semantic hairs here, but how is it not a copy of the address?It is a finely split hair - and ultimately just a difference of language use, I think.
We scribble on pieces of paper and thereby have at least two things to deal with: the scribble, and the location. It is unfortunate, but in English both things are referred to as "the address". The scribble has qualities like "red", "legible" etc, the location has qualities like "distant", "next door to the president": so they do seem to be different things.
We use "address" for both: "I can't read this address" vs "Go to this address". Children make jokes based on the ambiguity: "How do you spell it."
But then there's a third thing: the denotation of the location by the scribble. (denotation here == reference/pointing-at/leash/stick etc). It really does seem to be a third thing. (With apologies to Jean Buridan) consider a person who has lat/long coordinates explained to them for the first time and is handed a piece of paper with coordinates on it. They are asked "Do you know who lives here?" and they answer "Yes, I know the person at this address!". Most would say the statement is false - even if it turns out they were handed their own address. Their assertion of knowledge is an assertion about the denotation of the location by the coordinates, not about the location itself.
So what is copied by a scribe or a photocopy machine when it copies an address? Clearly it's the scribble, not the location. The scribble is duplicated, the location is not. But what about the denotation of the location by the scribble? Not withstanding the above example (and especially in contexts where knowledge and similar concepts are not involved), you could say that the denotation of the location by the scribble is a value. In other words you could hold that two denotations of some location are not just equal but identical iff they denote the same location. (You could, but you needn't.) It is in this sense that the pieces of paper bear, not copies of the address, but the same address.
(Exactly the same applies to "pointers" ie signposts. If you have two "north pole" signs (1) The are different signs (2) They point to the same place (3) They are two signs bearing one and the same reference.)
Edited by: pbrockway2 on Mar 15, 2009 12:49 PM

One view to call a method of another view

Hi all,
I have 2 views in a viewset. One view calls a bapi an brings back data into the context of the custom controller. Both views are linked to this custom controller. I have a method in view 1 which filters some data into a some value attributes in its context. I want to be able to call this method from view 2 so that it can perform this operation. Have I approached this the right way or should I be doing it another way?
All suggestions welcome and appreciated.
Regards,
Tony.

Hello Tony,
Same issue Re: Execute method from outside the view
Best regards, Maksim Rashchynski.

Calling a method in another JVM instance

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