BufferedWriter - writing a variable

[Jhon Calado]

Hey guys,
How are you?

I've started programming a few days ago so my post might be a little basic.

I'm trying to develop an application that writes to a file whatever I write in a textfield. I've been able to learn a lot on the web and I've been able to write a specific string into the file,but not the content of the textfield. Can't find any answers for this problem anywhere so I hope you can help.

Here's my code:

import javax.swing.*;  
import java.awt.event.*;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
 
public class swing_button_2 extends JFrame implements ActionListener {
 
        static Box vbox;
        static JButton button1;
        static JTextField entry1;
        
        public void actionPerformed(ActionEvent e) {
            String value=entry1.getText();           
            if(value.equals("A")){
            	JOptionPane.showMessageDialog(null, "Right");
            }
            else{
            	JOptionPane.showMessageDialog(null,"Wrong");
            }
        };
 
        public static void main (String[] args) {
 
                swing_button_2 frame = new swing_button_2("swing_button_2");
 
                frame.add(vbox);
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setSize(212, 258);
                frame.setVisible(true);
                
                try {

         
        			File file = new File("c:/Calado/gorjetas.txt");
         
        			// if file doesnt exists, then create it
        			if (!file.exists()) {
        				file.createNewFile();
        			}
         
        			FileWriter fw = new FileWriter(file.getAbsoluteFile(),true);
        			BufferedWriter bw = new BufferedWriter(fw);              
        			String value1 =entry1.getText();
        			bw.write(value1);
        			bw.close();
         
        			System.out.println("Done");
         
        		} catch (IOException e) {
        			e.printStackTrace();
        		}
        	}

       
        public swing_button_2(String title) {
 
                super(title);
 
                vbox = new Box(BoxLayout.Y_AXIS);
                button1 = new JButton("OK");
                entry1 = new JTextField("");
 
                button1.addActionListener(this); 
 
                vbox.add(button1);
                vbox.add(entry1);
 
        }

 }

I've tried defining value1 in different ways but nothing worked. If I define it as a simple string (like "Hey") it works. So I assume it has to do with the fact that it is a variable. I've looked for other methods to write with BufferedWriter but found nothing that solved the problem.PrintWriter doesn't do the trick either.I guess I'm stuck.

[Carles Gasques]

Hi,

Very simplistic and dirty
create a global variable FileWriter (initialized in the main method)
and move your BufferedWriter code from the main method to the actionPerformed method.


Cheers,

[K. Tsang]

Welcome to the Ranch.

From your code, you got the buttons to work ok. Now the question is if you want to write whatever you typed in the text box to the file, shouldn't the BufferedWriter code be inside the actionPerformed() method?

Further to what Carles said, you can also make the File variable global and move the FileWriter and BufferedWriter code inside actionPerformed(). Either way will work.

[Jhon Calado]

Thank you guys for the help.

I tried to integrate BufferedWriter in the actionPerformed method and set fw as global but is still not working.

import javax.swing.*;  
import java.awt.event.*;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
 
public class swing_button_2 extends JFrame implements ActionListener {
 
        static Box vbox;
        static JButton button1;
        static JTextField entry1;
        static FileWriter fw;
        
        public void actionPerformed(ActionEvent e) {
            String value=entry1.getText();           
			BufferedWriter bw = new BufferedWriter(fw);              
			try {
				bw.write(value);
			} catch (IOException e1) {
				// TODO Auto-generated catch block
				e1.printStackTrace();
			}
			try {
				bw.close();
			} catch (IOException e1) {
				// TODO Auto-generated catch block
				e1.printStackTrace();
			}
			System.out.println("Done");

            if(value.equals("A")){
            	JOptionPane.showMessageDialog(null, "Right");
            }
            else{
            	JOptionPane.showMessageDialog(null,"Wrong");
            }
        };
 
        public static void main (String[] args) {
 
                swing_button_2 frame = new swing_button_2("swing_button_2");
 
                frame.add(vbox);
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setSize(212, 258);
                frame.setVisible(true);
                
                try {

         
        			File file = new File("c:/Calado/gorjetas.txt");
         
        			// if file doesnt exists, then create it
        			if (!file.exists()) {
        				file.createNewFile();
        			}
         
        			FileWriter fw = new FileWriter(file.getAbsoluteFile(),true);
         
        		} catch (IOException e) {
        			e.printStackTrace();
        		}
        	}

       
        public swing_button_2(String title) {
 
                super(title);
 
                vbox = new Box(BoxLayout.Y_AXIS);
                button1 = new JButton("OK");
                entry1 = new JTextField("");
 
                button1.addActionListener(this); 
 
                vbox.add(button1);
                vbox.add(entry1);
 
        }

 }

Eclipse was telling me that a need an exception handling in my bw so I took the suggestion and let Eclipse correct it. I can run the frame,and introduce some text in the textfield but I got nothing on the file.

Probably I'm making some basic mistake that I'm not understanding.

[K. Tsang]

Did you get a NullPointerException? You are using a local FileWriter fw variable in main() where actionPerformed() uses the global variable.

[Jhon Calado]

Hey guys,

thanks for the help.It's working now.

Cheers