[z2104]

Hi, this program suppose to write a number of binary file and then generate them when I click read button but it doesn't.

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

public class RandomNum extends JFrame implements ActionListener{

private JPanel panButtons;
private JTextArea taDisplay;
private JButton btnWrite, btnRead;

    public RandomNum() {

    	panButtons = new JPanel();
    	btnWrite = new JButton("Write");
    	btnRead = new JButton("Read");
    	panButtons.add(btnWrite);
    	panButtons.add(btnRead);
    	btnWrite.addActionListener(this);
    	btnRead.addActionListener(this);

    	taDisplay = new JTextArea();

		Container c = getContentPane();
		c.setLayout(new BorderLayout());
		c.add(taDisplay);
		c.add(panButtons, BorderLayout.SOUTH);
    }

    	public void actionPerformed(ActionEvent e){
    		if(e.getSource () == btnWrite){

    			writeFile();

    		}

    		if(e.getSource() == btnRead){

				readFile();

    		}
    	}

    	public void writeFile(){

			String message = "";

			File filename = new File("binary.txt");

    		int n = (int) (Math.random() * 100 + 1);

    		for(n=0; n<=20; n++){
		try{
    			FileOutputStream fOut = new FileOutputStream(filename);
				DataOutputStream dOut = new DataOutputStream(fOut);
    			dOut.writeInt(n);
    			dOut.close();
    			message = "Done";
    			taDisplay.setText(message);

    		}
    		catch(IOException e){
    			taDisplay.setText("Error");
    		}
    		}

    	}


    	public void readFile(){

	  		FileInputStream fis = null;
	  		BufferedInputStream bis = null;
	  		DataInputStream dis = null;

			try{
				fis = new FileInputStream("binary.txt");
				bis = new BufferedInputStream(fis);
				dis = new DataInputStream(bis);

				while (dis.available() !=0){
					taDisplay.setText(dis.readLine());
				}

				fis.close();
				dis.close();
				bis.close();
			}
			catch(IOException i){

			}
    	}

			/*try{
				FileInputStream fis = new FileInputStream("binary.txt");
				DataInputStream dis = new DataInputStream(fis);
				BufferedReader br = new BufferedReader(new InputStreamReader(dis));
				String str;
				while ((str = br.readLine())!=null){
					taDisplay.append(str);
				}
				dis.close();
			}
			catch (IOException i){
				taDisplay.setText("Error" + i.getMessage());
			}*/

        public static void main(String[] args){

    		RandomNum frame = new RandomNum();
    		frame.setTitle("Random Number");
    		frame.setSize(850, 200);
    		frame.setVisible(true);
    		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }

}

[darek9576]

Not enturile sure but on line 57 you close the stream. Therefore it is going to write the first iteration and then its being closed. Take it out of the loop, so that the loop comlpletes and then close the stream. As i said, not sure. Try it.

[pbl]

darek9576, on 05 December 2010 - 10:27 AM, said:

Not enturile sure but on line 57 you close the stream. Therefore it is going to write the first iteration and then its being closed. Take it out of the loop, so that the loop comlpletes and then close the stream. As i said, not sure. Try it.

It is exactly that. You should
- new FileOutputStream()
- new DataOutputStream()
- perform the for() loop that write to the file
- close the stream

Righ now you create/open/close at each iteration of the loop

[z2104]

So am I doing the wrong way?

darek9576, on 05 December 2010 - 11:27 PM, said:

Not enturile sure but on line 57 you close the stream. Therefore it is going to write the first iteration and then its being closed. Take it out of the loop, so that the loop comlpletes and then close the stream. As i said, not sure. Try it.

I did what you told me to... but still the same

[Dogstopper]

Post your updated code.

[z2104]

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

public class RandomNum extends JFrame implements ActionListener{

private JPanel panButtons;
private JTextArea taDisplay;
private JButton btnWrite, btnRead;

    public RandomNum() {

    	panButtons = new JPanel();
    	btnWrite = new JButton("Write");
    	btnRead = new JButton("Read");
    	panButtons.add(btnWrite);
    	panButtons.add(btnRead);
    	btnWrite.addActionListener(this);
    	btnRead.addActionListener(this);

    	taDisplay = new JTextArea();

		Container c = getContentPane();
		c.setLayout(new BorderLayout());
		c.add(taDisplay);
		c.add(panButtons, BorderLayout.SOUTH);
    }

    	public void actionPerformed(ActionEvent e){
    		if(e.getSource () == btnWrite){

    			writeFile();

    		}

    		if(e.getSource() == btnRead){

				readFile();

    		}
    	}

    	public void writeFile(){

			String message = "";

			File filename = new File("binary.dat");

    		int n = (int) (Math.random() * 100 + 1);

    		for(n=0; n<=20; n++){
		try{
    			FileOutputStream fOut = new FileOutputStream(filename);
				DataOutputStream dOut = new DataOutputStream(fOut);
    			dOut.writeInt(n);
    			message = "Done";
    			taDisplay.setText(message);
				dOut.close();
    		}
    		catch(IOException e){
    			taDisplay.setText("Error");
    		}
    		}

    	}


    	public void readFile(){

	  		FileInputStream fis = null;
	  		BufferedInputStream bis = null;
	  		DataInputStream dis = null;

			try{
				fis = new FileInputStream("binary.dat");
				bis = new BufferedInputStream(fis);
				dis = new DataInputStream(bis);

				while (dis.available() !=0){
					taDisplay.setText(dis.readLine());
				}

				fis.close();
				dis.close();
				bis.close();
			}
			catch(IOException i){

			}
    	}

        public static void main(String[] args){

    		RandomNum frame = new RandomNum();
    		frame.setTitle("Random Number");
    		frame.setSize(850, 200);
    		frame.setVisible(true);
    		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }

}

This post has been edited by z2104: 06 December 2010 - 06:37 AM

[Dogstopper]

You have not effectively changed anything at all. You are still closing the stream INSIDE the loop. You have to move the close() call to after the loop.

[z2104]

You mean put the close() call outside the try-catch? or Outside for-loop? But it won't be able to find the variable (dOut), if I put outside.

[Dogstopper]

Yes. And you can, just change the scope.

                DataOutputStream dOut = null;
                for(n=0; n<=20; n++){
		try{
    			FileOutputStream fOut = new FileOutputStream(filename);
		        dOut = new DataOutputStream(fOut);
    			dOut.writeInt(n);
    			message = "Done";
    			taDisplay.setText(message);
				;
    		}
    		catch(IOException e){
    			taDisplay.setText("Error");
    		}
    		}
    		if (dOut != null)
    		    dOut.close();

[z2104]

Dogstopper, on 06 December 2010 - 08:47 PM, said:

Yes. And you can, just change the scope.

                DataOutputStream dOut = null;
                for(n=0; n<=20; n++){
		try{
    			FileOutputStream fOut = new FileOutputStream(filename);
		        dOut = new DataOutputStream(fOut);
    			dOut.writeInt(n);
    			message = "Done";
    			taDisplay.setText(message);
				;
    		}
    		catch(IOException e){
    			taDisplay.setText("Error");
    		}
    		}
    		if (dOut != null)
    		    dOut.close();

Hmm... I did what you told me to. There's an error says

unreported exception java.io.IOException; must be caught or declared to be thrown

Do I need to do try-catch?

[Dogstopper]

Yes. Or make the method throw it. One or the other.

[z2104]

Okay. By the way, thanks for your help

[Dogstopper]

You're Welcome. Glad I could help.

[m-e-g-a-z]

Dogstopper, on 06 December 2010 - 12:47 PM, said:

Yes. And you can, just change the scope.

                DataOutputStream dOut = null;
                for(n=0; n<=20; n++){
		try{
    			FileOutputStream fOut = new FileOutputStream(filename);
		        dOut = new DataOutputStream(fOut);
    			dOut.writeInt(n);
    			message = "Done";
    			taDisplay.setText(message);
				;
    		}
    		catch(IOException e){
    			taDisplay.setText("Error");
    		}
    		}
    		if (dOut != null)
    		    dOut.close();

And removing the extra semi-colon

[pbl]

Hey folks !!! You are drunk or tired ?

              DataOutputStream dOut = null;
              for(n=0; n<=20; n++){
try{
  			FileOutputStream fOut = new FileOutputStream(filename);
        dOut = new DataOutputStream(fOut);
  			dOut.writeInt(n);
  			message = "Done";
  			taDisplay.setText(message);
		;
  		}
  		catch(IOException e){
  			taDisplay.setText("Error");
  		}
  		}
  		if (dOut != null)
  		    dOut.close();

you are opening the file 20 times

            
              try {
  	           FileOutputStream fOut = new FileOutputStream(filename);
                   DataOutputStream dOut = new DataOutputStream(fOut);
                   for(n=0; n<=20; n++){
  			dOut.writeInt(n);
                   }
                   dout.close();
  		   message = "Done";
  		   taDisplay.setText(message);
  		}
  		catch(IOException e){
  			taDisplay.setText("Error");
  		}