Trying to get text from a text field to move to a text area

Question

package edu.bsu.cs121.mamurphy;

import java.awt.Dimension;
import java.awt.Toolkit;
import javax.swing.*;
import java.awt.event.*;

public class InClass1Main extends JFrame {

    JButton button1;
    JTextField textField1;
    JTextArea textArea1;
    int buttonClicked;

    public static void main(String[] args) {
        new InClass1Main();
    }

    public InClass1Main() {

        Toolkit tk = Toolkit.getDefaultToolkit();

        Dimension dim = tk.getScreenSize();
        this.setSize((dim.width / 2), (dim.height / 2));
        int xPos = (dim.width / 2) - (this.getWidth() / 2);
        int yPos = (dim.height / 2) - (this.getHeight() / 2);

        JPanel panel = new JPanel();
        JLabel label1 = new JLabel("Translation Panel");
        JButton button1 = new JButton("Transfer");

        ListenForButton button = new ListenForButton();

        button1.addActionListener(button);

        JTextField textField1 = new JTextField();
        JTextArea textArea1 = new JTextArea(10, 50);
        JScrollPane scrollBar1 = new JScrollPane(textArea1, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
                JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

        textField1.setColumns(50);

        textArea1.setLineWrap(true);
        textArea1.setWrapStyleWord(true);

        panel.add(label1);
        panel.add(button1);
        panel.add(textField1);
        panel.add(scrollBar1);

        this.add(panel);
        this.setLocation(xPos, yPos);
        this.setResizable(false);
        this.setTitle("Translation Frame");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);

        textField1.requestFocus();

    }

    private class ListenForButton implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent ae) {
            textArea1.setText(textField1.getText());
        }
    }
}

I am now getting an error whenever I try to actually type in text to the text field and then put it in the text area. I can't make any sense what so ever of the error.

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at edu.bsu.cs121.mamurphy.InClass1Main$ListenForButton.actionPerformed(InClass1Main.java:66)
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
    at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
    at java.awt.Component.processMouseEvent(Unknown Source)
    at javax.swing.JComponent.processMouseEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$500(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

I truly have no idea what caused this error. A lot of the reasons it is giving me (as you can see above) is (Unknown Source). So any help as to why this is happening would be greatly appreciated.

The error originates from *"edu.bsu.cs121.mamurphy.InClass1Main$ListenForButton.actionPerformed(InClass1Main.java:66)"* because you are shadowing your variables. See ControlAltDel's answer for more specific details — MadProgrammer, Nov 23 '15 at 21:54

score 2 · Answer 1 · answered Nov 23 '15 at 15:08

2

Remove the addActionListener statement from the body of ListenForButton

private class ListenForButton implements ActionListener {

    @Override
    public void actionPerformed(ActionEvent ae) {
        textArea1.setText(textField1.getText());
    }
}

answered Nov 23 '15 at 15:08

Reimeus

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15
216
276

So that did fix all of my errors, but now when I try and actually run my program to see if it actually works, I type in text and then I get a huge error in my code. I will add the error I get in an edit, as well as my updated code above. – MoeMarmalade Nov 23 '15 at 15:11
different issue: youre shadowing `JTextArea` and a bunch of other controls. Replace `JTextArea textArea1 = new JTextArea(...)` with `textArea1 = new JTextArea(...)`, etc... – Reimeus Nov 23 '15 at 15:16

score 1 · Answer 2 · answered Nov 23 '15 at 15:19

You've got a problem in your constructor in these lines:

    JTextField textField1 = new JTextField();
    JTextArea textArea1 = new JTextArea(10, 50);

What you probably want is

    textField1 = new JTextField();
    textArea1 = new JTextArea(10, 50);

This will set your object members, rather than putting them in method local variables.

score 0 · Answer 3 · answered Nov 23 '15 at 15:23

Here is you complete solution...

import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class InClass1Main extends JFrame{
        JButton button1;
        public static JTextField textField1;
        public static JTextArea textArea1;
        int buttonClicked;

        public static void main(String[] args) {
            new InClass1Main();
        }

        public InClass1Main() {

            Toolkit tk = Toolkit.getDefaultToolkit();

            Dimension dim = tk.getScreenSize();
            this.setSize((dim.width / 2), (dim.height / 2));
            int xPos = (dim.width / 2) - (this.getWidth() / 2);
            int yPos = (dim.height / 2) - (this.getHeight() / 2);

            JPanel panel = new JPanel();
            JLabel label1 = new JLabel("Translation Panel");
            JButton button1 = new JButton("Transfer");

            ListenForButton button = new ListenForButton();

            button1.addActionListener(button);

            textField1 = new JTextField();
            textArea1 = new JTextArea(10, 50);
            JScrollPane scrollBar1 = new JScrollPane(textArea1, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
                    JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

            textField1.setColumns(50);

            textArea1.setLineWrap(true);
            textArea1.setWrapStyleWord(true);

            panel.add(label1);
            panel.add(button1);
            panel.add(textField1);
            panel.add(scrollBar1);

            this.add(panel);
            this.setLocation(xPos, yPos);
            this.setResizable(false);
            this.setTitle("Translation Frame");
            this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            this.setVisible(true);

            textField1.requestFocus();

        }


}

class ListenForButton implements ActionListener {

    @Override
    public void actionPerformed(ActionEvent ae) {
        System.out.println("Hello");
        System.out.println(InClass1Main.textField1.getText());
        System.out.println(InClass1Main.textArea1.getText());
        InClass1Main.textArea1.setText(InClass1Main.textField1.getText());
    }
}

Madushan Perera · Accepted Answer · 2015-11-23T15:21:27.293

This will solve the issues in your code :

    public class InClass1Main extends JFrame {

    JTextField textField1;
    JTextArea textArea1;
    int buttonClicked;

    public static void main(String[] args) {
        new InClass1Main();
    }

    public InClass1Main() {

        Toolkit tk = Toolkit.getDefaultToolkit();

        Dimension dim = tk.getScreenSize();
        this.setSize((dim.width / 2), (dim.height / 2));
        int xPos = (dim.width / 2) - (this.getWidth() / 2);
        int yPos = (dim.height / 2) - (this.getHeight() / 2);

        JPanel panel = new JPanel();
        JLabel label1 = new JLabel("Translation Panel");
        JButton button1 = new JButton("Transfer");

        ListenForButton button = new ListenForButton();

        button1.addActionListener(button);

        textField1 = new JTextField();//no need to declare any other JTextField object just initialize the above crated 
        textArea1 = new JTextArea(10, 50);//same here
        JScrollPane scrollBar1 = new JScrollPane(textArea1, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
                JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

        textField1.setColumns(50);

        int numOfLines = textArea1.getLineCount();

        textArea1.setLineWrap(true);
        textArea1.setWrapStyleWord(true);
        textArea1.append(" Number of lines: " + numOfLines);

        panel.add(label1);
        panel.add(button1);
        panel.add(textField1);
        panel.add(scrollBar1);

        this.add(panel);
        this.setLocation(xPos, yPos);
        this.setResizable(false);
        this.setTitle("Translation Frame");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);

        textField1.requestFocus();

    }

    private class ListenForButton implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
        new InClass1Main().textArea1.setText(textField1.getText());
        new InClass1Main().textField1.setText(null);
        }

    }

Thanks a lot. This actually solves all of the problems I was having. — MoeMarmalade, Nov 23 '15 at 15:16
I would like to ask though. How can I make it so that the text in the text field goes away, and the text in the text area stay? So for example, you type in `This is a test.` So that goes in the text field. Then you type in `This is the next text.` and that text also goes in the text field, but doesn't overwrite what was put in previously? — MoeMarmalade, Nov 23 '15 at 15:19
how textArea1 as well as textField1 is accessible while it is totally out of scope. It's not Valid code. — Vishal Gajera, Nov 23 '15 at 15:21

Trying to get text from a text field to move to a text area

4 Answers4