Calling a class method from another class

how can i call a method / function of one class without extending that class in another class.
and one thing more i want want o check wether any Swing gui is open or closed.

how can i call a method / function of one class without extending that class in another class.What?... Umm... You just call it... as in Foo.bar("doe ray me");
i want want to check if any Swing gui is open or closed.Ummm, what? I don't understand the question. Do you mean find out if a particular java programming is allready running, of do you mean is the JPanel visible, or something else?

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Calling a servlet method from another class

hi...
if i make a servlet (that keeps the log for website users' logins and logouts, for example) and i want a method that adds an entry into a logfile, for example:
public void log(String line) {
//put "line" into some log file...
and then i set this servlet to loadonstartup, how can i call the log() function from other classes or servlets? can i do it without making the servlet an entry in servletContext?
im sorry if i'm not being very clear, the caffeine's getting to me...
thanks
lazlo

I don't know, why would you do that anyway? Just make an ordinary class, not a servlet, and make "log" a static method in that class. (If you need initialization, use a static initializer.) Put that class where the real servlet can see it and call it from there.

Calling a static method from another class

public class Command
    public static void sortCommands(String command, String order, List object)
         if(command.equalsIgnoreCase("merge") && order == "a")
              object.setAscending(true);
              Mergesort.mergesort(object.list);                  // line 85
}and
public class Mergesort
     public static void mergesort (int[] a)
          mergesort(a, 0, a.length-1);
     private static void mergesort (int[] a, int l, int r)
     private static void merge (int[] a, int l, int m, int r)
}Error:
Command.java:85: cannot find symbol
symbol : variable Mergesort
location: class Command
Mergesort.mergesort(object.list)
What am I doing wrong here? Within the Command class I am calling mergesort(), a static method, from a static method. I use the dot operator + object so that the compiler would recognize the 'list' array. I tried using the
Mergesort.mergesort(object.list);notation in hopes that it would work like this:
Class.staticMethod(parameters);but either I am mistaken, misunderstood the documentation or both. Mergesort is not a variable. Any help would be appreciated, I have been hitting a brick wall for hours with Java documentation. Thanks all.

[Javapedia: Classpath|http://wiki.java.net/bin/view/Javapedia/ClassPath]
[How Classes are Found|http://java.sun.com/j2se/1.5.0/docs/tooldocs/findingclasses.html]
[Setting the class path (Windows)|http://java.sun.com/j2se/1.5.0/docs/tooldocs/windows/classpath.html]
[Setting the class path (Solaris/Linux)|http://java.sun.com/j2se/1.5.0/docs/tooldocs/solaris/classpath.html]
[Understanding the Java ClassLoader|http://www-106.ibm.com/developerworks/edu/j-dw-javaclass-i.html]
java -cp .;<any other directories or jars> YourClassNameYou get a NoClassDefFoundError message because the JVM (Java Virtual Machine) can't find your class. The way to remedy this is to ensure that your class is included in the classpath. The example assumes that you are in the same directory as the class you're trying to run.
javac -classpath .;<any additional jar files or directories> YourClassName.javaYou get a "cannot resolve symbol" message because the compiler can't find your class. The way to remedy this is to ensure that your class is included in the classpath. The example assumes that you are in the same directory as the class you're trying to run.

How to call a C function calling a Java Method from another C function ?

Hi everyone,
I'm just starting to learn JNI and my problem is that I don't know if it is possible to call a C function calling a Java Method (or doing anything else with JNI) from another C function.
In fact, after receiving datas in a socket made by a C function, I would like to create a class instance (and I don't know how to do it too ; ) ) and init this instance with the strings I received in the socket.
Is all that possible ?
Thank you very much for your help !

Hard to understand the question, but by most interpretations the answer is going to be yes.
You do of course understand that JNI is the "API" that sits between Java and C and that every call between the two must go through that. You can't call it directly.

HOW TO CALL A JSP METHOD FROM ANOTHER JSP

Hi all, I have to JSP1 and JSP2 and i would like to call a method of JS1 from JSP2. Is that possible ??
Example:
JSP2 Code
somewhere in the code ...
String s = JSP1.getName();
out.println("EL NOMBRE ES " +s );
thanks in advance for your help

No, it is not possible. Infact you cannot write your own methods in JSP. What ever you write in a jsp page is part of _jspService() method. Secondly how can you instantiate another class(generated by JSP), until or unless you know the name of the class that resulted from your JSP. Your JSP page is first converted into .java file which is stored in some package e.g.
pagecompile.jsp._yourJSPfile.
I couldnot understand why you need to invoke a method of another JSP in your JSP.
Hope this helps

Through Enhancement, how to call a Webdynpro method from another webdynpro?

I have a standard page with 2 iViews with a standard abap webdynpro in each.
The first webdynpro needs to refresh the second webdynpro.
Through enhancement, I tried to follow the solution below:
first of all in the child component's component controller method(which you want to expose to another component) must be checked in the interface column.
Double click on the webdynpro project(parent component)->In the used components tab, in the column of component type the child project name(whose method you want to call) and in component usage column give any name->save the project.
goto the controller(VIEW or COMPONENT) from where you want to call the method->click create controller usage->select the interface controller of the child component->save the project.
click the code wizard->select method call in used controller->select the child component interface controller ->select the method you want to call.
Link of thread: Calling a method of other webdynpro component
But this solution doesn't worked because in this standard webdynpro is not possible to check the method as Interface.
Is there other way to do this?
Thanks.

Hello,
you can refer the following documentation for portal eventing
http://help.sap.com/saphelp_nw70/helpdata/en/f6/7d6f4151dc5758e10000000a1550b0/frameset.htm
Br, Saravanan

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

Calling a TextFields get method from another class as a String

This is my first post so be kind....
I'm trying to create a login screen with Java Studio Creator. The Login.jsp has a Text Field for both the username and password. JSC automatically created get and set methods for these.
public class Login extends AbstractPageBean
private TextField usernameTF = new TextField();
public TextField getUsernameTF() {
return usernameTF;
public void setUsernameTF(TextField tf) {
this.usernameTF = tf;
private PasswordField passwordTF = new PasswordField();
public PasswordField getPasswordTF() {
return passwordTF;
public void setPasswordTF(PasswordField pf) {
this.passwordTF = pf;
My problem is in trying to call these methods from another class and return the value as a string.
Any help on this matter would be greatly appreciated.

the method returns the textfield, so you just need to get its text
import java.awt.*;
class Testing
public Testing()
    Login login = new Login();
    System.out.println(login.getUsernameTF().getText());//<----
public static void main(String[] args){new Testing();}
class Login
private TextField usernameTF = new TextField("Joe Blow");
public TextField getUsernameTF() {
    return usernameTF;
}

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?

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!!

Is it possible to call methods from another class from within an abstract c

Is it possible to call methods from another class from within an abstract class ?

I found an example in teh JDK 131 JFC that may help you. I t is using swing interface and JTable
If you can not use Swing, then you may want to do digging or try out with the idea presented here in example 3
Notice that one should refine the abstract table model and you may want to create a method for something like
public Object getValuesAtRow(int row) { return data[row;}
to give the desired row and leave the method for
getValuesAt alone for getting valued of particaular row and column.
So Once you got the seelcted row index, idxSelctd, from your table
you can get the row or set the row in your table model
public TableExample3() {
JFrame frame = new JFrame("Table");
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {System.exit(0);}});
// Take the dummy data from SwingSet.
final String[] names = {"First Name", "Last Name", "Favorite Color",
"Favorite Number", "Vegetarian"};
final Object[][] data = {
     {"Mark", "Andrews", "Red", new Integer(2), new Boolean(true)},
     {"Tom", "Ball", "Blue", new Integer(99), new Boolean(false)},
     {"Alan", "Chung", "Green", new Integer(838), new Boolean(false)},
     {"Jeff", "Dinkins", "Turquois", new Integer(8), new Boolean(true)},
     {"Amy", "Fowler", "Yellow", new Integer(3), new Boolean(false)},
     {"Brian", "Gerhold", "Green", new Integer(0), new Boolean(false)},
     {"James", "Gosling", "Pink", new Integer(21), new Boolean(false)},
     {"David", "Karlton", "Red", new Integer(1), new Boolean(false)},
     {"Dave", "Kloba", "Yellow", new Integer(14), new Boolean(false)},
     {"Peter", "Korn", "Purple", new Integer(12), new Boolean(false)},
     {"Phil", "Milne", "Purple", new Integer(3), new Boolean(false)},
     {"Dave", "Moore", "Green", new Integer(88), new Boolean(false)},
     {"Hans", "Muller", "Maroon", new Integer(5), new Boolean(false)},
     {"Rick", "Levenson", "Blue", new Integer(2), new Boolean(false)},
     {"Tim", "Prinzing", "Blue", new Integer(22), new Boolean(false)},
     {"Chester", "Rose", "Black", new Integer(0), new Boolean(false)},
     {"Ray", "Ryan", "Gray", new Integer(77), new Boolean(false)},
     {"Georges", "Saab", "Red", new Integer(4), new Boolean(false)},
     {"Willie", "Walker", "Phthalo Blue", new Integer(4), new Boolean(false)},
     {"Kathy", "Walrath", "Blue", new Integer(8), new Boolean(false)},
     {"Arnaud", "Weber", "Green", new Integer(44), new Boolean(false)}
// Create a model of the data.
TableModel dataModel = new AbstractTableModel() {
// These methods always need to be implemented.
public int getColumnCount() { return names.length; }
public int getRowCount() { return data.length;}
public Object getValueAt(int row, int col) {return data[row][col];}
// The default implementations of these methods in
// AbstractTableModel would work, but we can refine them.
public String getColumnName(int column) {return names[column];}
public Class getColumnClass(int col) {return getValueAt(0,col).getClass();}
public boolean isCellEditable(int row, int col) {return (col==4);}
public void setValueAt(Object aValue, int row, int column) {
data[row][column] = aValue;
};

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

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][

Use a method from another class in another package?

How can I use a method from another class in another package?

WhiteJ wrote:
What do you mean by "new keyword?" You posted this previously:
I tried that, it seems to not be working. I want to use the constructor from the other class. I imported it, using this piece of code:
import components.FileChooser;
components.FileChoser();
Typically if I am going to call a constructor on a class called Fubar, I'd use new to create a new object:
Fubar myFubar = new Fubar();Incidently, is it a simple typo in your post or are you trying to use a FileChoser object when it should be FileChooser?

Running a main Method from another class??

Hi,
I am trying to run a main method from another class, eg the main method is in Class1 and i am trying to run it from class2.
So I have
class1 c1 = new class1();
c1.main();and I get the following compilation error:
clas2.java:42: main(java.lang.String[]) in class1 cannot be applied to () c1.main();
any ideas on how to do this correctly
thanks in advance,
Donal

Hi thanks for the replies,
tried just passing a string earlier and that just gave errors too, I should have been more specific and pass a string array.
Its working now thanks again.
Donal

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 class method from another class

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