Need help with a program I`ve written......

Ruthie-Roux

Hi there,

Not sure if this is the right place for this so mods feel free to move as appropriate.
Im having major issues with a program Ive written for a college assigment due in tommorow. It`s compilling without errors but when I try and run it it says:Exception in thread "main" java.lang.NoSuchMethodError: main
Press any key to continue . . .

If there are any programmers about, could you have a look over this code and advise me where I`ve gone wrong.....under pressure to have this soon and havent got a clue why it won`t run.

Thanks,

Ruth

---

import java.io.*;
import java.awt.*;
import java. awt.event.*;

public class CreditUnion
{
private int account;
private String lastName;
private String firstName;
private double balance;

//read a record from the specified RandomAccessFile
public void read(RandomAccessFile file) throws IOException
{
account=file.readInt();

char first[] =new char[ 15 ];

for (int i=0; i < first.length;i++)
first [ i ]=file.readChar();

firstName =new String ( first );

char last[]= new char [ 15 ];

for (int i=0; i < last.length; i++)
last [ i ]=file.readChar();

lastName =new String( last);



balance=file.readDouble();

}

//write a record to the specified RandomAccessFile
public void write( RandomAccessFile file ) throws IOException
{
StringBuffer buf;

file.writeInt( account );

if (firstName !=null )
buf= new StringBuffer( firstName );
else
buf =new StringBuffer( 15 );

buf.setLength( 15 );

file.writeChars( buf.toString() );

if (lastName != null)
buf =new StringBuffer( lastName );
else
buf= new StringBuffer( 15 );

buf .setLength( 15 );

file.writeChars( buf.toString() );

file.writeDouble( balance );
}

public void setAccount( int a ) {account = a;}
public int getAccount() {return account; }
public void setfirstName( String f ) {firstName =f;}
public String getfirstName() {return firstName;}
public void setlastName( String l ) {lastName =l;}
public String getlastName() {return lastName;}
public void setBalance( double b ) {balance =b;}
public double getBalance() {return balance; }

//Note: This method contains a hard coded value for the
//size of a record of information
public static int size() { return 72;}
}

CreepingDeath

You haven't defined a main() method to call your other methods.
Eg.

public static void main(String[] args)
{
    try
    {
    CreditUnion instance = new CreditUnion();

    File f = new File("CreditUnion.dat");
    RandomAccessFile raf = new RandomAccessFile(f, "rw"); 

     // set the account no, name etc

    instance.write(raf);

    instance.read(raf);
    }
    catch(Exception ex)
    {
        ex.printStackTrace();
    }

}

NeverSayDie

As per CreepingDeath's post, you can't run programs in Java without some kind of main() method for them to start from. See here;
http://java.sun.com/docs/books/tutorial/getStarted/application/index.html#MAIN

Ruthie-Roux

NeverSayDie wrote: »

As per CreepingDeath's post, you can't run programs in Java without some kind of main() method for them to start from. See here;
http://java.sun.com/docs/books/tutorial/getStarted/application/index.html#MAIN

Thats what I thought. But Im working off examples like below which do run perfectly without public static void main etc.

import java.io.*;
import java.awt.*;
import java. awt.event.*;
//Import packages

public class WriteRandomFile extends Frame
implements ActionListener
{


private TextField numberField,NameField,

withdrawalField, balanceField;
//TextField where user enters account info


private Button enter,
//send record to file
done;
//quit program



// Application other pieces
private RandomAccessFile output ;
// file for output
private Record data;


public WriteRandomFile ()
//This constructor initializes the frame
{
super("Write to random access file");
data = new Record();

//Open the file

try {
output = new RandomAccessFile( "credit.dat","rw");

}

catch (IOException e) {
System.err.println(e .toString() );
System.exit(1);
}

setSize(300,150);
setLayout( new GridLayout(5,2) );

//Create the new components of the Frame
add( new Label( " Number") ) ;
numberField = new TextField ();
add(numberField);


add ( new Label(" Name " ) ) ;
NameField= new TextField( 20);
add (NameField);

add( new Label ( "Current Balance ") ) ;
balanceField = new TextField( 20);
add(balanceField);


add( new Label ( " Withdrawal limit ") ) ;
withdrawalField = new TextField( 20);
add(withdrawalField);

enter = new Button ( "Enter ");
enter.addActionListener(this);
add(enter);

done = new Button ("Done ");
done.addActionListener(this);
add(done);

setVisible(true);

}

public void addRecord()
{
int Number = 0;
Double d ;

if (! numberField.getText().equals("") ) {




//output the values to the file
try {

Number =
Integer.parseInt(accountField.getText() );


if ( Number> 0 && Number <= 100) {

data.setAccount( accountNumber);
data.setName(NameField.getText() );
data.setWithdrawal(WithdrawalField.getText() );
d = new Double (balanceField.getText() );
data.setBalance( d.doubleValue () );

output. seek(
( long) (Number-1) * Record.size() );
data.write(output);
}


//clear the textfields
accountField.setText(" ");
firstNameField.setText("");

lastNameField.setText("");
balanceField.setText("");
}

catch (NumberFormatException nfe) {

System.err.println(
" you must enter an integer account number");
}

catch (IOException io) {
System.err.println(
"Error during write to file\n"+
io.toString() );
System.exit(1);
}
}
}

public void actionPerformed(ActionEvent e )
{
addRecord();

if ( e.getSource() ==done) {
try {
output.close();
}
catch(IOException io) {
System.err.println("File not closed properly\n"+ io.toString());
}
System.exit(0);
}
}

//Instantiate a writeRandomFile object and start the program
public static void main (String args[] )
{
new WriteRandomFile();
}
}

CreepingDeath

Ruthie-Roux wrote: »

Thats what I thought. But Im working off examples like below which do run perfectly without public static void main etc.

  //Instantiate a writeRandomFile object and start the program
  public static void main (String args[] )
  {
	 new WriteRandomFile();
   }
}

That example does have a main method.


You have to have a main method "somewhere", and start your program from that class.
Either
a) have the main method within the CreditUnion class or
b) create a separate class eg. CreditUnionApplication which has a main method and calls the CreditUnion class methods.

NeverSayDie

Your example does have a main() method - down the very end of the code you posted

Edit - beaten to it

Ruthie-Roux

Oh so it does :rolleyes:

Where is my head today? Thanks folks, I really should have seen that.
Need coffee. Yes. More coffee.

Ruth