JTextArea. How can I replace text when printing new one?

Question

I created JFrame and JTextArea above it. JTextArea has defaul text "This is text for demo version", that has been set via setText() method.

The goal is to implement this logic: If I start printing text, the old text should be deleted and new one should apper. After that, when new text is printed and if I click "Enter" - new text should be saved into private ArrayList<String> textList

The main question is How to replace old text when I print the first symbol of my text?

I tried to add TestTextArea.this.replaceRange(keyText,0, 30); inside keyReleased(KeyEvent e) {}; (30 it's the last index of default string "This is text for demo version" ). But everytime when I print anything, it causes IllegalArgumentException and seems that old text is still visible on the background.

import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;

import static javax.swing.WindowConstants.EXIT_ON_CLOSE;

public class TestTextArea extends JTextArea {

    private String text = "This is text for demo version";
    private ArrayList<String> textList = new ArrayList<>();

    TestTextArea() {
        setBackground(new Color(23, 28, 34, 240));
        setForeground(new Color(6, 200, 109));
        setCaretColor(new Color(6, 200, 109));
        setCaretPosition(0);
        setFont(new Font("Helvetica Neue", Font.BOLD, 16));
        setText(text);
        setLineWrap(true);
        setWrapStyleWord(true);
        setFocusable(true);
        setEnabled(true);
        setEditable(true);
        setVisible(true);

        addKeyListener(new KeyListener() {
            @Override
            public void keyTyped(KeyEvent e) {

            }

            @Override
            public void keyPressed(KeyEvent e) {

            }

            @Override
            public void keyReleased(KeyEvent e) {
                String keyText = KeyEvent.getKeyText(e.getKeyCode());
                TestTextArea.this.replaceRange(keyText,0, 30);
                if (keyText.equals("Enter")) {
                    textList.add(TestTextArea.this.getText());
                }
            }
        });

    }
    public static void main(String []args) {
        JFrame f = new JFrame();

        TestTextArea area = new TestTextArea();
        f.add(area);

        f.setSize(400,200);
        f.setDefaultCloseOperation(EXIT_ON_CLOSE);
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }
}

Is there any another way to solve this? I want that after I type the text and press Enter, all the text that I typed is saved. But at the moment it turns out that when you enter the first character, the default text is deleted, but even no one character is saved.

I am sorry, in advance for the possibly not very successful statement of the problem.

Answer 1

I think I understand your requirements.

• When the first character is typed, clear the JTextArea and capture the typed text in the JTextArea,

• When the Enter key is pressed, save the typed text in the List.

This code meets these requirements.

I use a JTextArea. The only reason you extend a Swing component, or any Java class, is to override one or more of the class methods.

I set the size of the JTextArea in the JTextArea constructor. Then I pack the JFrame.

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;
import java.util.List;

import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;

public class TextEntryExample implements Runnable {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new TextEntryExample());
    }
    
    private List<String> textList;
    
    private String text;
    
    private JTextArea textArea;
    
    public TextEntryExample() {
        this.text = "This is text for demo version";
        this.textList = new ArrayList<>();
    }

    @Override
    public void run() {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        this.textArea = createPrompt();
        f.add(textArea, BorderLayout.CENTER);

        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }
    
    private JTextArea createPrompt() {
        JTextArea textArea = new JTextArea(10, 30);
        textArea.addKeyListener(new PromptListener());
        textArea.setBackground(new Color(23, 28, 34, 240));
        textArea.setForeground(new Color(6, 200, 109));
        textArea.setCaretColor(new Color(6, 200, 109));
        textArea.setCaretPosition(0);
        textArea.setFont(new Font("Helvetica Neue", Font.BOLD, 16));
        textArea.setText(text);
        textArea.setLineWrap(true);
        textArea.setWrapStyleWord(true);
        
        return textArea;
    }
    
    public class PromptListener implements KeyListener {
        
        private boolean entry;
        
        public PromptListener() {
            this.entry = false;
        }

        @Override
        public void keyTyped(KeyEvent e) {
        }

        @Override
        public void keyPressed(KeyEvent event) {
            if (!entry) {
                String oldText = textArea.getText();
                textArea.replaceRange("", 0, oldText.length());
                entry = true;
            }
        }

        @Override
        public void keyReleased(KeyEvent event) {
            if (entry) {
                String keyText = KeyEvent.getKeyText(event.getKeyCode());
                if (keyText.equals("Enter")) {
                    textList.add(textArea.getText());
                    entry = false;
                }
            } 
        }
        
    }

}

Answer 2

This might not be the easiest, but you could replace the document with one that clears the text on the first edit.

I haven't checked, but I think JTextArea uses a DefaultStyledDocument. You can extend that and override the editing methods to check a flag - if it's set, clear the text and clear the flag. I've done something similar this for JTextField (using PlainDocument) - here's how that would look:

public class PromptDocument
    extends PlainDocument
{
    private bool clearOnEdit = false;

    public void insertString(int offset, String str, AttributeSet a)
        throws BadLocationException
    {
        if (clearOnEdit) {
            super.remove(offset, getLength());
            clearOnEdit = false;
        }
        super.insertString(offset, str, a);
    }
    public void remove(int offset, int len)
        throws BadLocationException
    {
        if (clearOnEdit) {
            super.remove(offset, getLength());
            clearOnEdit = false;
        } else {
            super.remove(offset, len);
        }
    }
    public void setClearOnEdit(final boolean clear) {
        clearOnEdit = clear;
    }
}

It should be similar for JTextArea (I haven't tested this, might be missing things). You can just use setDocument() on your JTextArea after you create it.