Standard/common handling void main(String argv[])

i would like to have a parent class to handle the void main(String argv[]), but I can't instantiate my child class because I dun know it's name.
any way to get that? or any alternative way to handle the void main(String argv[]) in common? million thanks.
eg:
public abstract class parent {
public static void main(String argv[]){
// i need to know which child is been run by java childclass
// so that I can instantiate a new object and call the run method
public abstract void run();
public class child1 extends parent{
public void run(){}
public class child2 extends parent{
public void run(){}
}

Class.forName(name).newInstance();
provided I know name=what, right?
how do I know ppl calling using
java child1?
or
java child2?
both will go use same
public static void main(String argv[])
in parent class.

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How to call java with public static void main(String[] args) throws by jsp?

how do i call this from jsp? <%spServicelnd temp = new spServicelnd();%> does not work because the program has a main. can i make another 2nd.java to call this spServiceInd.java then call 2nd.java by jsp? if yes, how??? The code is found below...
import java.net.MalformedURLException;
import java.io.IOException;
import com.openwave.wappush.*;
public class spServiceInd
     private final static String ppgAddress = "http://devgate2.openwave.com:9002/pap";
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//     private final static String[] clientAddress = {"+639209063665/[email protected]"};
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          System.out.println("hello cze, I'm inside printResult");
          //Read the response to find out if the Push Submission succeded.
          //1001 = "Accepted for processing"
          if (pushResponse.getResultCode() == 1001)
               try
                    String pushID = pushResponse.getPushID();
                    SimplePush sp = new SimplePush(new java.net.URL(ppgAddress), "SampleApp", "/sampleapp");
                    StatusQueryResponse queryResponse = sp.queryStatus(pushID, null);
                    StatusQueryResult queryResult = queryResponse.getResult(0);
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               catch (WapPushException exception)
                    System.out.println("*** ERROR - WapPushException (" + exception.getMessage() + ")");
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In general, classes with main method should be called from command prompt (that's the reason for main method). Remove the main method, put the class in a package and import the apckage in your jsp (java classes should not be in the location as jsps).
When you import the package in jsp, then you can instantiate the class and use any of it's methods or call the statis methods directly:
<%
spServiceInd spsi = new spServiceInd();
spsi.SubmitMsg();
%>

Why can't created an object in the "public static void main(String args[])"

Example:
public Class Exp {
public static void main(String args[])
new Exp2();-------------> To Occur Error
Class Exp2 {
public Exp2()

You can't create an inner class within main, because
it is a static method. Inner classes can only be
created by true class methods.This is not correct. You can create an inner class object in a static method. You just have to specify an outer class object that the inner class object should be created within:
Exp2 exp2 = new Exp().new Exp2();

Static private void main(String[]) works (?!)

Did anyone knew that?
try yourself!!
public class Foo {
static private void main (String[] bla) {
//anything
}there's even a bug!! And Sun choose not fix it:
http://developer.java.sun.com/developer/bugParade/bugs/4252539.html
I'd like to hear what you folks think about this...
IMO: fuc* encapsulation!

No, I haven't done the certification exam and I have no plans to. But the answer to that question isstatic public void main (String[] bla)and the fact that other versions happen to work doesn't matter either theoretically or practically. Bugs that appear in certain implementations of Java shouldn't matter.

Private static void main(String args[]) ... ?????

even if the main method is declared
private static void main(String args[])
//Code Here
it works fine..can somebody explain the reason behind?

hi rkippen
so u mean, since the JVM is calling the main it can
break all kinds of access specifiers to any class..am
i right?
This could be the case.
However, I tried using 1.4.1 with no development environment (just java.exe) and it gave the following error:
C:\>java MainTest
Main method not public.
So, your development environment might be the cause (e.g. what you use to program your code (e.x. JBuilder)), or the Java version.
Your development environment might be using reflection to get around Java accessibility checks. For debugging purposes, it is possible to use reflection to obtain refereneces to private methods/fields and invoke those methods and access those fields.
E.g.
Vector v = new Vector();
Field f = v.getClass().getDeclaredField("elementCount");
f.setAccessible(true); // this is the trick
f.set(v, new Integer(100));In the presence of a security manager, the setAccessible method will fire a "suppressAccessChecks" permission check.

Why doyou pass string[] argv to main?

I was just wondering why when you call the main method you pass a string array tto it? I just always did it without thinking about it and now im looking at the following code that uses argv-
public static void main(String[] argv)
        try
            for(int i=0; i < argv.length; i++)
                if(argv.endsWith(".class"))
I can't figure out why its using argv and what it's doing.

If that method were invoked by the VM while someone
started it up on the command-line like this (let's
pretend the class that main method belongs to is
called Foo):
java Foo one two three
The strings "one", "two", and "three" are stuffed
into a String array of size 3, and passed to
main(String[] argv). argv is that array.Thanks, I understand what the code is doing now.

Void mains

Please help, I have just about had enough of this code for my lifetime.
I am trying to get a timer running in the background that fires an event every minute.
I had the code:
public class Apl
    public static void main(String argv[])
        boolean gui = true;
        int portNum = 110;
        //server object
     POP3Server server;
        //user mailset
        Set mailSet = new HashSet();
        . //does some stuff
}So i try and modify it to do this
e.g
public class Apl
    public static void main(String argv[])
        boolean gui = true;
        int portNum = 110;
        //server object
     POP3Server server;
        //user mailset
        Set mailSet = new HashSet();
        . //does some stuff
        TimerTask fetchMail = new FetchMail();
        Timer timer = new Timer();
        timer.scheduleAtFixedRate(fetchMail, 1, 10000);
    public class FetchMail()
        System.out.println("HI");
}In the hope it would print HI every 10 seconds. But no.
Any ideas? Thanks

Still having problems with this timer. I have had a rethink about what I want to do with it and am still having problems.
private String makeMailDrop()
        String users = "";
        String thisLine;
        //DOES SOME STUFF HEREThen from another class
public POP3Server(int port, POP3ServerFrame frame, Set mailSet)
         //vars
          this.port = port;
          this.frame = frame;
          this.mailSet = mailSet;
          gui=true;
                uidlArr = new String[100];
                counter = 1;
          //timer
          //makeTimer();
          output("Initializing..this may take a while..\n");
                output("Welcome To Highway42 POP3 Server. \n\n");
                makeMailDrop();
                TimerTask loopMD = makeMailDrop();
                Timer timer = new Timer();
                timer.scheduleAtFixedRate(loopMD, 1, 10000);The problem being that the types are different, loopMD is a TimerTask and I am trying to assign it to a methiod that returns a string.
so I tried TimerTask loopMD = makeMailDrop();and then it says it cant find makeMailDrop().
How would I implement this so on the timer it runs makeMailDrop()
Thanks

Standard input - main(String[] args) -- how?

In eclipse, how do I feed the main with values?
public static void main(String[] args) {
     System.out.println("Enter value: ");
     args =
    if (args.length != 1) {
...Thanks,
george

You mean basically command line arguments?
Look in the run menu. For every run event there's a form that specifies how to invoke the program. Somewhere in there you can specifiy the command line arguments. I can't recall right now but I can look it up if you can't find it.
Standard input is a completely different thing from command line arguments. Standard input, from the java point of view, is what comes in on System.in.

When does the Java main(String args[]) method exit?

Hi all,
I and my colleagues want to know, when does the main() method exit?
we wrote a small code as follows:
import java.awt.*;
public class Test {
public static void main(String[] args) {
Frame f = new Frame("hi");
f.show();
System.out.println("after show");
and ran the program, in which case I could see the printed message "after show", but although there is no code after the System.out.println(), the Java virtual machine does not exit and waits for the Frame to close.
My question is has the main method exited in this case? since it clearly shows that it does not have any more code to execute. Does java create the main method as a thread or as a process?
regards,
Harshad

To make your application terminate you need to add code to cause the AWT thread to handle the termination. In your code, before f.show(), try:
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
dispose();
public void windowClosed(WindowEvent e) {
System.exit(0);
});Now, at least you can click on the little "X" on the upper right-hand corner of the Frame (at least in Win95/98/NT) environments) to cause your application to receive a window closing event. It is also possible to add a menu with an option to exit; in that case I'd use an EventQueue to cause a window closing event to be sent.

Default access specifiers for void main()

I m having one problem that if i make void main(String a[])
syntax like private static void main(String args[]) and run using jdk1.4 it will run. So my question is that why this is possible still i making main() private. If i run it in jdk1.5.0 then it give error main is not public so what was the problem with the jdk1.4?

Congratulations on your first post after almost 2
years. ?The most impressive thing is that he remembered his
password ...I posted by first message in 2004, I only used this account to read the bugdatabase and vote on bugs prior to that. So I don't see anything strange in having an account, and not using the forums.
Kaj
Ps. But I'm also impressed by the fact that he remembered the password, I had an account which I created in -97, but I forgot the password to that account :(

Can't find file when use the main(String[] args) method

I put a file under the DefaultDomain directory of Weblogic 11.1.1.5 on my local machine. Below is how I look up this file
FileInputStream fis = new FileInputStream("input.xml");
I started up the IntegratedWeblogicServer instance and I tested using the below 2 approaches.
1) When I test a web service program using the below approach, it CAN'T find the input.xml file
public static void main(String[] args)
2) When I package it into an EAR file and deploy it onto the server then log into the admin console and use the test client approach then it's able to find the file
How do I make it so it can find the file using #1 approach?
Thanks

That's how relative paths work, and it's nothing particular to Java.
When you type ls input.xml or dir input.xml does it list the file, or give an error? If it lists the file, then it's in your current directory, and it will work if you run Java from that directory. If it gives an error, then that file is not in your current working directory, and Java won't be able to find it either.

What happens when main(String[] args)

Hi techies,
I am trying to understand, "how the JVM invokes public static void main(String[] args)".
I had gone through JVM tutorial, and found that there are 2 different types of classloaders 1. bootstrap loader 2. user defined class loader.
I had gone through java api for class loader class. i did not find the method main(String[] args).
I am having confusion whether bootstrap loader calls main(String[] args)(or) userdefined classloader calles main(String[] args).
Why do we have to give String[] args as argument to main??
can you guys guide to understand this .
regards,
Krishna

Hi techies,
I am trying to understand, "how the JVM
invokes public static void main(String[] args)".
I had gone through JVM tutorial, and
found that there are 2 different types of
classloaders 1. bootstrap loader 2. user defined
class loader.
I had gone through java api for class
loader class. i did not find the method
main(String[] args).
I am having confusion whether bootstrap
loader calls main(String[] args)(or) userdefined
classloader calles main(String[] args).
Why do we have to give String[] args as
argument to main??
can you guys guide to understand this
regards,
Krishnawell, you won't find main(String[] args) in the docs for ClassLoader, since it's not a method on ClassLoader!
the bootstrap loader loads, verifies, prepares and initializes the class for which you pass the fully.qualified.name into the JVM, and looks for the static method on that class called 'main' which has a single argument, an array of Strings, and no return type ( I'm not 100% sure of that last part actually - I'll try it ) and begins a thread of execution on that method. from there, your program is run
we have to give an array of Strings in order to pass arguments into the program
it can't be a user-defined classloader that does this, because most of the time there won't be a user-defined classloader!

Why should i write main(String[] args)?

Hello,
I don't know why i am obliged in the main function of the class to send an array of string as parameters?
Thanks

Actually I think this is a great question!
main()
Any java application has to have a main method to do anything, but as you gain further into java and object orientated practices you will start writing lots of stuff that do NOT have a main method but are *.java and *.class files, neither will they do anything unless they are attached to a program with a main. Andthen as you get DEEPER still you might even have 'private synchronised void main(String[] args)' - though not too often.
Why an array of strings? Hmmm ...pauses ...thinks, there is no obvious reason, other than the fact that if you're going to pass parameters from 'java ...' command line to the application. This is, logically, the most potentially useful data type to have. There may well be other reasons for this, so the answer to the second part of your question is a logical deduction - it may not be right.

Main(String args[]) cannot be overload ? True or False

main(String args[]) cannot be overload ? True or False

Although you can do this....
public class a
    public static void main(String[] args)
        System.out.println("Hello World - a!");
public class b extends a
    public static void main(String[] args)
        System.out.println("Hello World - b!");
}(I'm not sure if that is relevant to your actual question.... but then again your question isn't spot on either! ;-)

Void main

Hi,
Could you please let me know what is wrong with this line please:
Employee test= new Emp_FT(getId,getFirstName,getLastName,getEmployeeAge,getFullTime);
          public static void main(String args[])
                     Employee test= new Emp_FT(getId,getFirstName,getLastName,getEmployeeAge,getFullTime);
     class Emp_FT extends Employee{
         private String fulltime;
        public Emp_FT( int id, String firstName, String lastName, int employee_age, String address, String ft )
                  super( id, firstName, lastName, employee_age, address);
                    this.fulltime = ft;
                }Thanks
Andonny

    public ArrayList parseFile(File input)
        String buffer = null;
        ArrayList data = new ArrayList();
        try
            FileReader fileIn = new FileReader(input);
            BufferedReader bufferIn = new BufferedReader(fileIn);
            buffer = bufferIn.readLine();
            while (buffer != null)
                    //write code here depending on how you arrange your file
                    //store values for name and id in local variables then create
                    //a new employee, if it is a fulltime employee then
                    Emp_FT emp = new Emp_FT(id, first, last, ssn, etc);
                    //or you could create an empoyee first then add the info
                    Emp_FT emp = new Emp_FT();
                    emp.setId(something);
                    emp.setFirstName(something);
                    //then add this employee to your list before proceeding
                    data.add(emp);
                buffer = bufferIn.readLine();
            bufferIn.close();
        catch (IOException e)
            e.printStackTrace();
        return data;
    }

Standard/common handling void main(String argv[])

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