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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
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 * particular file as subject to the "Classpath" exception as provided
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 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package javafx.scene.control;

import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

import javafx.beans.InvalidationListener;
import javafx.beans.property.BooleanProperty;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.WritableValue;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.css.CssMetaData;
import javafx.css.StyleConverter;
import javafx.css.StyleableBooleanProperty;
import javafx.css.StyleableIntegerProperty;
import javafx.css.StyleableProperty;

import com.sun.javafx.binding.ExpressionHelper;
import com.sun.javafx.collections.ListListenerHelper;
import com.sun.javafx.collections.NonIterableChange;
import javafx.css.converter.SizeConverter;
import javafx.scene.control.skin.TextAreaSkin;

import javafx.css.Styleable;
import javafx.scene.AccessibleRole;

Text input component that allows a user to enter multiple lines of plain text. Unlike in previous releases of JavaFX, support for single line input is not available as part of the TextArea control, however this is the sole-purpose of the TextField control. Additionally, if you want a form of rich-text editing, there is also the HTMLEditor control. 
TextArea supports the notion of showing prompt text to the user when there is no text already in the TextArea (either via the user, or set programmatically). This is a useful way of informing the user as to what is expected in the text area, without having to resort to tooltips or on-screen labels. 
See Also:
TextField
Since:
JavaFX 2.0/**
 * Text input component that allows a user to enter multiple lines of
 * plain text. Unlike in previous releases of JavaFX, support for single line
 * input is not available as part of the TextArea control, however this is
 * the sole-purpose of the {@link TextField} control. Additionally, if you want
 * a form of rich-text editing, there is also the
 * {@link javafx.scene.web.HTMLEditor HTMLEditor} control.
 *
 * <p>TextArea supports the notion of showing {@link #promptTextProperty() prompt text}
 * to the user when there is no {@link #textProperty() text} already in the
 * TextArea (either via the user, or set programmatically). This is a useful
 * way of informing the user as to what is expected in the text area, without
 * having to resort to {@link Tooltip tooltips} or on-screen {@link Label labels}.
 *
 * @see TextField
 * @since JavaFX 2.0
 */
public class TextArea extends TextInputControl {
    // Text area content model
    private static final class TextAreaContent implements Content {
        private ExpressionHelper<String> helper = null;
        private ArrayList<StringBuilder> paragraphs = new ArrayList<StringBuilder>();
        private int contentLength = 0;
        private ParagraphList paragraphList = new ParagraphList();
        private ListListenerHelper<CharSequence> listenerHelper;

        private TextAreaContent() {
            paragraphs.add(new StringBuilder(DEFAULT_PARAGRAPH_CAPACITY));
            paragraphList.content = this;
        }

        @Override public String get(int start, int end) {
            int length = end - start;
            StringBuilder textBuilder = new StringBuilder(length);

            int paragraphCount = paragraphs.size();

            int paragraphIndex = 0;
            int offset = start;

            while (paragraphIndex < paragraphCount) {
                StringBuilder paragraph = paragraphs.get(paragraphIndex);
                int count = paragraph.length() + 1;

                if (offset < count) {
                    break;
                }

                offset -= count;
                paragraphIndex++;
            }

            // Read characters until end is reached, appending to text builder
            // and moving to next paragraph as needed
            StringBuilder paragraph = paragraphs.get(paragraphIndex);

            int i = 0;
            while (i < length) {
                if (offset == paragraph.length()
                    && i < contentLength) {
                    textBuilder.append('\n');
                    paragraph = paragraphs.get(++paragraphIndex);
                    offset = 0;
                } else {
                    textBuilder.append(paragraph.charAt(offset++));
                }

                i++;
            }

            return textBuilder.toString();
        }

        @Override
        @SuppressWarnings("unchecked")
        public void insert(int index, String text, boolean notifyListeners) {
            if (index < 0
                || index > contentLength) {
                throw new IndexOutOfBoundsException();
            }

            if (text == null) {
                throw new IllegalArgumentException();
            }
            text = TextInputControl.filterInput(text, false, false);
            int length = text.length();
            if (length > 0) {
                // Split the text into lines
                ArrayList<StringBuilder> lines = new ArrayList<StringBuilder>();

                StringBuilder line = new StringBuilder(DEFAULT_PARAGRAPH_CAPACITY);
                for (int i = 0; i < length; i++) {
                    char c = text.charAt(i);

                    if (c == '\n') {
                        lines.add(line);
                        line = new StringBuilder(DEFAULT_PARAGRAPH_CAPACITY);
                    } else {
                        line.append(c);
                    }
                }

                lines.add(line);

                // Merge the text into the existing content
                // Merge the text into the existing content
                int paragraphIndex = paragraphs.size();
                int offset = contentLength + 1;

                StringBuilder paragraph = null;

                do {
                    paragraph = paragraphs.get(--paragraphIndex);
                    offset -= paragraph.length() + 1;
                } while (index < offset);

                int start = index - offset;

                int n = lines.size();
                if (n == 1) {
                    // The text contains only a single line; insert it into the
                    // intersecting paragraph
                    paragraph.insert(start, line);
                    fireParagraphListChangeEvent(paragraphIndex, paragraphIndex + 1,
                        Collections.singletonList((CharSequence)paragraph));
                } else {
                    // The text contains multiple line; split the intersecting
                    // paragraph
                    int end = paragraph.length();
                    CharSequence trailingText = paragraph.subSequence(start, end);
                    paragraph.delete(start, end);

                    // Append the first line to the intersecting paragraph and
                    // append the trailing text to the last line
                    StringBuilder first = lines.get(0);
                    paragraph.insert(start, first);
                    line.append(trailingText);
                    fireParagraphListChangeEvent(paragraphIndex, paragraphIndex + 1,
                        Collections.singletonList((CharSequence)paragraph));

                    // Insert the remaining lines into the paragraph list
                    paragraphs.addAll(paragraphIndex + 1, lines.subList(1, n));
                    fireParagraphListChangeEvent(paragraphIndex + 1, paragraphIndex + n,
                        Collections.EMPTY_LIST);
                }

                // Update content length
                contentLength += length;
                if (notifyListeners) {
                    ExpressionHelper.fireValueChangedEvent(helper);
                }
            }
        }

        @Override public void delete(int start, int end, boolean notifyListeners) {
            if (start > end) {
                throw new IllegalArgumentException();
            }

            if (start < 0
                || end > contentLength) {
                throw new IndexOutOfBoundsException();
            }

            int length = end - start;

            if (length > 0) {
                // Identify the trailing paragraph index
                int paragraphIndex = paragraphs.size();
                int offset = contentLength + 1;

                StringBuilder paragraph = null;

                do {
                    paragraph = paragraphs.get(--paragraphIndex);
                    offset -= paragraph.length() + 1;
                } while (end < offset);

                int trailingParagraphIndex = paragraphIndex;
                int trailingOffset = offset;
                StringBuilder trailingParagraph = paragraph;

                // Identify the leading paragraph index
                paragraphIndex++;
                offset += paragraph.length() + 1;

                do {
                    paragraph = paragraphs.get(--paragraphIndex);
                    offset -= paragraph.length() + 1;
                } while (start < offset);

                int leadingParagraphIndex = paragraphIndex;
                int leadingOffset = offset;
                StringBuilder leadingParagraph = paragraph;

                // Remove the text
                if (leadingParagraphIndex == trailingParagraphIndex) {
                    // The removal affects only a single paragraph
                    leadingParagraph.delete(start - leadingOffset,
                        end - leadingOffset);

                    fireParagraphListChangeEvent(leadingParagraphIndex, leadingParagraphIndex + 1,
                        Collections.singletonList((CharSequence)leadingParagraph));
                } else {
                    // The removal spans paragraphs; remove any intervening paragraphs and
                    // merge the leading and trailing segments
                    CharSequence leadingSegment = leadingParagraph.subSequence(0,
                        start - leadingOffset);
                    int trailingSegmentLength = (start + length) - trailingOffset;

                    trailingParagraph.delete(0, trailingSegmentLength);
                    fireParagraphListChangeEvent(trailingParagraphIndex, trailingParagraphIndex + 1,
                        Collections.singletonList((CharSequence)trailingParagraph));

                    if (trailingParagraphIndex - leadingParagraphIndex > 0) {
                        List<CharSequence> removed = new ArrayList<CharSequence>(paragraphs.subList(leadingParagraphIndex,
                            trailingParagraphIndex));
                        paragraphs.subList(leadingParagraphIndex,
                            trailingParagraphIndex).clear();
                        fireParagraphListChangeEvent(leadingParagraphIndex, leadingParagraphIndex,
                            removed);
                    }

                    // Trailing paragraph is now at the former leading paragraph's index
                    trailingParagraph.insert(0, leadingSegment);
                    fireParagraphListChangeEvent(leadingParagraphIndex, leadingParagraphIndex + 1,
                        Collections.singletonList((CharSequence)leadingParagraph));
                }

                // Update content length
                contentLength -= length;
                if (notifyListeners) {
                    ExpressionHelper.fireValueChangedEvent(helper);
                }
            }
        }

        @Override public int length() {
            return contentLength;
        }

        @Override public String get() {
            return get(0, length());
        }

        @Override public void addListener(ChangeListener<? super String> changeListener) {
            helper = ExpressionHelper.addListener(helper, this, changeListener);
        }

        @Override public void removeListener(ChangeListener<? super String> changeListener) {
            helper = ExpressionHelper.removeListener(helper, changeListener);
        }

        @Override public String getValue() {
            return get();
        }

        @Override public void addListener(InvalidationListener listener) {
            helper = ExpressionHelper.addListener(helper, this, listener);
        }

        @Override public void removeListener(InvalidationListener listener) {
            helper = ExpressionHelper.removeListener(helper, listener);
        }

        private void fireParagraphListChangeEvent(int from, int to, List<CharSequence> removed) {
            ParagraphListChange change = new ParagraphListChange(paragraphList, from, to, removed);
            ListListenerHelper.fireValueChangedEvent(listenerHelper, change);
        }
    }

    // Observable list of paragraphs
    private static final class ParagraphList extends AbstractList<CharSequence>
            implements ObservableList<CharSequence> {

        private TextAreaContent content;

        @Override
        public CharSequence get(int index) {
            return content.paragraphs.get(index);
        }

        @Override
        public boolean addAll(Collection<? extends CharSequence> paragraphs) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean addAll(CharSequence... paragraphs) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean setAll(Collection<? extends CharSequence> paragraphs) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean setAll(CharSequence... paragraphs) {
            throw new UnsupportedOperationException();
        }

        @Override
        public int size() {
            return content.paragraphs.size();
        }

        @Override
        public void addListener(ListChangeListener<? super CharSequence> listener) {
            content.listenerHelper = ListListenerHelper.addListener(content.listenerHelper, listener);
        }

        @Override
        public void removeListener(ListChangeListener<? super CharSequence> listener) {
            content.listenerHelper = ListListenerHelper.removeListener(content.listenerHelper, listener);
        }

        @Override
        public boolean removeAll(CharSequence... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public boolean retainAll(CharSequence... elements) {
            throw new UnsupportedOperationException();
        }

        @Override
        public void remove(int from, int to) {
            throw new UnsupportedOperationException();
        }

        @Override
        public void addListener(InvalidationListener listener) {
            content.listenerHelper = ListListenerHelper.addListener(content.listenerHelper, listener);
        }

        @Override
        public void removeListener(InvalidationListener listener) {
            content.listenerHelper = ListListenerHelper.removeListener(content.listenerHelper, listener);
        }
    }

    private static final class ParagraphListChange extends NonIterableChange<CharSequence>  {

        private List<CharSequence> removed;

        protected ParagraphListChange(ObservableList<CharSequence> list, int from, int to,
            List<CharSequence> removed) {
            super(from, to, list);

            this.removed = removed;
        }

        @Override
        public List<CharSequence> getRemoved() {
            return removed;
        }

        @Override
        protected int[] getPermutation() {
            return new int[0];
        }
    };

    
The default value for prefColumnCount. /**
     * The default value for {@link #prefColumnCountProperty() prefColumnCount}.
     */
    public static final int DEFAULT_PREF_COLUMN_COUNT = 40;

    
The default value for prefRowCount. /**
     * The default value for {@link #prefRowCountProperty() prefRowCount}.
     */
    public static final int DEFAULT_PREF_ROW_COUNT = 10;

    private static final int DEFAULT_PARAGRAPH_CAPACITY = 32;

    
Creates a TextArea with empty text content. /**
     * Creates a {@code TextArea} with empty text content.
     */
    public TextArea() {
        this("");
    }

    
Creates a TextArea with initial text content. 
Params:
text – A string for text content./**
     * Creates a {@code TextArea} with initial text content.
     *
     * @param text A string for text content.
     */
    public TextArea(String text) {
        super(new TextAreaContent());

        getStyleClass().add("text-area");
        setAccessibleRole(AccessibleRole.TEXT_AREA);
        setText(text);
    }

    @Override final void textUpdated() {
        setScrollTop(0);
        setScrollLeft(0);
    }

    
Returns an unmodifiable list of the character sequences that back the
text area's content.
Returns:
an unmodifiable list of the character sequences that back the
text area's content/**
     * Returns an unmodifiable list of the character sequences that back the
     * text area's content.
     * @return an unmodifiable list of the character sequences that back the
     * text area's content
     */
    public ObservableList<CharSequence> getParagraphs() {
        return ((TextAreaContent)getContent()).paragraphList;
    }


    /***************************************************************************
     *                                                                         *
     * Properties                                                              *
     *                                                                         *
     **************************************************************************/

    
If a run of text exceeds the width of the TextArea, then this variable indicates whether the text should wrap onto another line. /**
     * If a run of text exceeds the width of the {@code TextArea},
     * then this variable indicates whether the text should wrap onto
     * another line.
     */
    private BooleanProperty wrapText = new StyleableBooleanProperty(false) {
        @Override public Object getBean() {
            return TextArea.this;
        }

        @Override public String getName() {
            return "wrapText";
        }

        @Override public CssMetaData<TextArea,Boolean> getCssMetaData() {
            return StyleableProperties.WRAP_TEXT;
        }
    };
    public final BooleanProperty wrapTextProperty() { return wrapText; }
    public final boolean isWrapText() { return wrapText.getValue(); }
    public final void setWrapText(boolean value) { wrapText.setValue(value); }


    
The preferred number of text columns. This is used for calculating the TextArea's preferred width. /**
     * The preferred number of text columns. This is used for
     * calculating the {@code TextArea}'s preferred width.
     */
    private IntegerProperty prefColumnCount = new StyleableIntegerProperty(DEFAULT_PREF_COLUMN_COUNT) {

        private int oldValue = get();

        @Override
        protected void invalidated() {
            int value = get();
            if (value < 0) {
                if (isBound()) {
                    unbind();
                }
                set(oldValue);
                throw new IllegalArgumentException("value cannot be negative.");
            }
            oldValue = value;
        }

        @Override public CssMetaData<TextArea,Number> getCssMetaData() {
            return StyleableProperties.PREF_COLUMN_COUNT;
        }

        @Override
        public Object getBean() {
            return TextArea.this;
        }

        @Override
        public String getName() {
            return "prefColumnCount";
        }
    };
    public final IntegerProperty prefColumnCountProperty() { return prefColumnCount; }
    public final int getPrefColumnCount() { return prefColumnCount.getValue(); }
    public final void setPrefColumnCount(int value) { prefColumnCount.setValue(value); }


    
The preferred number of text rows. This is used for calculating the TextArea's preferred height. /**
     * The preferred number of text rows. This is used for calculating
     * the {@code TextArea}'s preferred height.
     */
    private IntegerProperty prefRowCount = new StyleableIntegerProperty(DEFAULT_PREF_ROW_COUNT) {

        private int oldValue = get();

        @Override
        protected void invalidated() {
            int value = get();
            if (value < 0) {
                if (isBound()) {
                    unbind();
                }
                set(oldValue);
                throw new IllegalArgumentException("value cannot be negative.");
            }

            oldValue = value;
        }

        @Override public CssMetaData<TextArea,Number> getCssMetaData() {
            return StyleableProperties.PREF_ROW_COUNT;
        }

        @Override
        public Object getBean() {
            return TextArea.this;
        }

        @Override
        public String getName() {
            return "prefRowCount";
        }
    };
    public final IntegerProperty prefRowCountProperty() { return prefRowCount; }
    public final int getPrefRowCount() { return prefRowCount.getValue(); }
    public final void setPrefRowCount(int value) { prefRowCount.setValue(value); }


    
The number of pixels by which the content is vertically
scrolled.
/**
     * The number of pixels by which the content is vertically
     * scrolled.
     */
    private DoubleProperty scrollTop = new SimpleDoubleProperty(this, "scrollTop", 0);
    public final DoubleProperty scrollTopProperty() { return scrollTop; }
    public final double getScrollTop() { return scrollTop.getValue(); }
    public final void setScrollTop(double value) { scrollTop.setValue(value); }


    
The number of pixels by which the content is horizontally
scrolled.
/**
     * The number of pixels by which the content is horizontally
     * scrolled.
     */
    private DoubleProperty scrollLeft = new SimpleDoubleProperty(this, "scrollLeft", 0);
    public final DoubleProperty scrollLeftProperty() { return scrollLeft; }
    public final double getScrollLeft() { return scrollLeft.getValue(); }
    public final void setScrollLeft(double value) { scrollLeft.setValue(value); }


    /***************************************************************************
     *                                                                         *
     * Methods                                                                 *
     *                                                                         *
     **************************************************************************/

    
{@inheritDoc} /** {@inheritDoc} */
    @Override protected Skin<?> createDefaultSkin() {
        return new TextAreaSkin(this);
    }


    
                                                                        *
Stylesheet Handling                                                     *
                                                                        *
/***************************************************************************
     *                                                                         *
     * Stylesheet Handling                                                     *
     *                                                                         *
     **************************************************************************/

    private static class StyleableProperties {
        private static final CssMetaData<TextArea,Number> PREF_COLUMN_COUNT =
            new CssMetaData<TextArea,Number>("-fx-pref-column-count",
                SizeConverter.getInstance(), DEFAULT_PREF_COLUMN_COUNT) {

            @Override
            public boolean isSettable(TextArea n) {
                return !n.prefColumnCount.isBound();
            }

            @Override
            public StyleableProperty<Number> getStyleableProperty(TextArea n) {
                return (StyleableProperty<Number>)(WritableValue<Number>)n.prefColumnCountProperty();
            }
        };

        private static final CssMetaData<TextArea,Number> PREF_ROW_COUNT =
            new CssMetaData<TextArea,Number>("-fx-pref-row-count",
                SizeConverter.getInstance(), DEFAULT_PREF_ROW_COUNT) {

            @Override
            public boolean isSettable(TextArea n) {
                return !n.prefRowCount.isBound();
            }

            @Override
            public StyleableProperty<Number> getStyleableProperty(TextArea n) {
                return (StyleableProperty<Number>)(WritableValue<Number>)n.prefRowCountProperty();
            }
        };

        private static final CssMetaData<TextArea,Boolean> WRAP_TEXT =
            new CssMetaData<TextArea,Boolean>("-fx-wrap-text",
                StyleConverter.getBooleanConverter(), false) {

            @Override
            public boolean isSettable(TextArea n) {
                return !n.wrapText.isBound();
            }

            @Override
            public StyleableProperty<Boolean> getStyleableProperty(TextArea n) {
                return (StyleableProperty<Boolean>)(WritableValue<Boolean>)n.wrapTextProperty();
            }
        };

        private static final List<CssMetaData<? extends Styleable, ?>> STYLEABLES;
        static {
            final List<CssMetaData<? extends Styleable, ?>> styleables =
                new ArrayList<CssMetaData<? extends Styleable, ?>>(TextInputControl.getClassCssMetaData());
            styleables.add(PREF_COLUMN_COUNT);
            styleables.add(PREF_ROW_COUNT);
            styleables.add(WRAP_TEXT);
            STYLEABLES = Collections.unmodifiableList(styleables);
        }
    }

    
Returns:
The CssMetaData associated with this class, which may include the
CssMetaData of its superclasses.
Since:
JavaFX 8.0/**
     * @return The CssMetaData associated with this class, which may include the
     * CssMetaData of its superclasses.
     * @since JavaFX 8.0
     */
    public static List<CssMetaData<? extends Styleable, ?>> getClassCssMetaData() {
        return StyleableProperties.STYLEABLES;
    }

    
{@inheritDoc}
Since:
JavaFX 8.0/**
     * {@inheritDoc}
     * @since JavaFX 8.0
     */
    @Override
    public List<CssMetaData<? extends Styleable, ?>> getControlCssMetaData() {
        return getClassCssMetaData();
    }
}