Writing To A TextFile From A JTextArea

**anthropamorphic** · 09-11-2011, 02:07 AM

Hello, I have been having this problem for a while now, but my problem is I can't
seem to be able to write to a text file if I get the text from a JTextField. I have tried so many different approaches to it and I can't seem to figure it out.

This is what I am using to write to the file:

Java Code:

	public void write(File file, String string){
		try {
			BufferedWriter Te = null;
			System.out.println(file);
			
			Te = new BufferedWriter(new FileWriter(file));
			System.out.println("BufferWriter and FileWriter Obtained File and it should be writing " + string);
			Te.write(string);
			Te.newLine();
			Te.close();
			System.out.println("Success While Writer");
		} catch (IOException e) {
			// TODO Auto-generated catch block
			System.out.println("error when writing to a file");
		}
	}

and here is part of my class that is using this subroutine:

Java Code:

public class event implements ActionListener{
		public void actionPerformed(ActionEvent e){
			ReadWrite wr = new ReadWrite();
			wr.write(file2, te.getText());
		}
	}

Here are the errors I am getting

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at Open$event.actionPerformed(Open.java:43)
at javax.swing.AbstractButton.fireActionPerformed(Abs tractButton.java:2028)
at javax.swing.AbstractButton$Handler.actionPerformed (AbstractButton.java:2351)
at javax.swing.DefaultButtonModel.fireActionPerformed (DefaultButtonModel.java:387)
at javax.swing.DefaultButtonModel.setPressed(DefaultB uttonModel.java:242)
at javax.swing.plaf.basic.BasicButtonListener.mouseRe leased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.jav a:6373)
at javax.swing.JComponent.processMouseEvent(JComponen t.java:3267)
at java.awt.Component.processEvent(Component.java:613 8)
at java.awt.Container.processEvent(Container.java:208 5)
at java.awt.Component.dispatchEventImpl(Component.jav a:4735)
at java.awt.Container.dispatchEventImpl(Container.jav a:2143)
at java.awt.Component.dispatchEvent(Component.java:45 65)
at java.awt.LightweightDispatcher.retargetMouseEvent( Container.java:4621)
at java.awt.LightweightDispatcher.processMouseEvent(C ontainer.java:4282)
at java.awt.LightweightDispatcher.dispatchEvent(Conta iner.java:4212)
at java.awt.Container.dispatchEventImpl(Container.jav a:2129)
at java.awt.Window.dispatchEventImpl(Window.java:2478 )
at java.awt.Component.dispatchEvent(Component.java:45 65)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.j ava:679)
at java.awt.EventQueue.access$000(EventQueue.java:85)
at java.awt.EventQueue$1.run(EventQueue.java:638)
at java.awt.EventQueue$1.run(EventQueue.java:636)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:87)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:98)
at java.awt.EventQueue$2.run(EventQueue.java:652)
at java.awt.EventQueue$2.run(EventQueue.java:650)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 649)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:296)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:211)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:196)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:188)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:122)

**Fubarable** · 09-11-2011, 02:14 AM

Which line causes the NullPointerException (NPE) to be thrown? Could it be this one?

Java Code:

wr.write(file2, te.getText());

if so, is te null? Have you tested to see if it is?

**anthropamorphic** · 09-11-2011, 02:25 AM

Originally Posted by Fubarable

Which line causes the NullPointerException (NPE) to be thrown? Could it be this one?

Java Code:

wr.write(file2, te.getText());

if so, is te null? Have you tested to see if it is?

hmm I didn't test to see that I don't think it is but I will try it right now I need to fix something in my code and then I will try what you recommended.

**Fubarable** · 09-11-2011, 02:41 AM

Also, you know that text components like JTextFields and JTextAreas have the write method, an innate facility for writing out the text contained to a text file.

**anthropamorphic** · 09-11-2011, 02:43 AM

Originally Posted by Fubarable

Also, you know that text components like JTextFields and JTextAreas have the write method, an innate facility for writing out the text contained to a text file.

They do? How do I use it?

**anthropamorphic** · 09-11-2011, 02:47 AM

Originally Posted by anthropamorphic

hmm I didn't test to see that I don't think it is but I will try it right now I need to fix something in my code and then I will try what you recommended.

You were right! It isn't getting the text from the textarea for some reason? I though I was suppose to just use (name of textarea).getText(); is there a different way to do it?

**anthropamorphic** · 09-11-2011, 02:48 AM

I think I am suppose to use a document listener I will try it and tell you if it worked.

**Fubarable** · 09-11-2011, 02:50 AM

Originally Posted by anthropamorphic

You were right! It isn't getting the text from the textarea for some reason? I though I was suppose to just use (name of textarea).getText(); is there a different way to do it?

It has nothing to do with variable name and all to do with object reference. Your ta variable in that method is not referencing any object much less the valid JTextArea of interest. There's no way of knowing why based on the code you're posting. Sometimes we see this when newbies inappropriately extend a class to access its variables, but again, I have no idea if this is what is happening in your code.

**anthropamorphic** · 09-11-2011, 02:55 AM

Originally Posted by Fubarable

It has nothing to do with variable name and all to do with object reference. Your ta variable in that method is not referencing any object much less the valid JTextArea of interest. There's no way of knowing why based on the code you're posting. Sometimes we see this when newbies inappropriately extend a class to access its variables, but again, I have no idea if this is what is happening in your code.

Would you want me to post my code?
the the variable is this:

Java Code:

JTextArea te;

Java Code:

JTextArea te = new JTextArea(out , 3, 5);
frame.add(te, BorderLayout.CENTER);
te.setBorder(BorderFactory.createLineBorder(Color.BLACK));

That's all the code that relates to the the variable.

**Fubarable** · 09-11-2011, 03:00 AM

Originally Posted by anthropamorphic

Would you want me to post my code?
the the variable is this:

Java Code:

JTextArea te;

Java Code:

JTextArea te = new JTextArea(out , 3, 5);
frame.add(te, BorderLayout.CENTER);
te.setBorder(BorderFactory.createLineBorder(Color.BLACK));

That's all the code that relates to the the variable.

What you've posted in no way shows us what your problem is. Don't post all the code, just enough code so we can solve the problem. I know -- it's not easy to know what that is, and that's part of the art of asking questions here. Don't worry, you'll get better at this skill with time. ;)

**anthropamorphic** · 09-11-2011, 03:04 AM

Alright here is the class I am having trouble with:

Java Code:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;


public class Open {
	JButton save;
	JTextArea te;
	File file2;
	public void open(File file){
		ReadWrite wr = new ReadWrite();
		
		file2 = file;
		List l = new List();
		wr.read(file);
		System.out.println("File Loaded = " + file);
		String out = wr.output;
		System.out.println(out);
		System.out.println(wr.output);
		JTextArea te = new JTextArea(out , 3, 5);
		JFrame frame = new JFrame();
		frame.setLayout(new BorderLayout());
		frame.setSize(330, 345);
		frame.setVisible(true);
		frame.add(te, BorderLayout.CENTER);
		JPanel pa = new JPanel();
		pa.setBackground(Color.LIGHT_GRAY);
		te.setBorder(BorderFactory.createLineBorder(Color.BLACK));
		frame.add(pa, BorderLayout.PAGE_START);
		JButton save = new JButton("    Save    ");
		pa.setForeground(Color.BLACK);
		pa.setBorder(BorderFactory.createLineBorder(Color.BLACK));
		pa.add(save);
		event e = new event();
		save.addActionListener(e);
	}
	public class event implements ActionListener{
		public void actionPerformed(ActionEvent e){
			Open op = new Open();
			String tein = te.getText();
			System.out.println("The File You Are Saving is" + file2 + "\n" + "The Text You Are Saving In The File Is" + tein);
			ReadWrite wr = new ReadWrite();
			wr.write(file2, tein);
		}
	}
}

**Fubarable** · 09-11-2011, 03:11 AM

Originally Posted by anthropamorphic

Alright here is the class I am having trouble with:

Geeze, that Norm must have a crystal ball because we were just now discussing this issue in a different thread. Your problem is one of variable shadowing, that you have two te variables, one that refers to a valid JTextArea object, and one that is null. Check out your code:

Java Code:

//...

public class Open {
	JButton save;
	JTextArea te;  // here is the class field that is never initialized
	File file2;

	public void open(File file){
		// ....


		// and here is the shadowed variable that is declared in the open method and only visible inside the open method:
		JTextArea te = new JTextArea(out , 3, 5); 


		// ....

	}

	public class event implements ActionListener{
		public void actionPerformed(ActionEvent e){
			Open op = new Open();


			String tein = te.getText();  // guess which te variable is being used here??
			
			
			// ....
		}
	}
}

The solution is not to re-declare the variable in the open method. Instead do this:

Java Code:

//...

public class Open {
	JButton save;
	JTextArea te;  // te declared once here
	File file2;

	public void open(File file){
		// ....


		// *******  don't re-declare te *******
		te = new JTextArea(out , 3, 5);  // te initialized but NOT declared here


		// ....

	}