在jtextarea中显示行数的Java代码

Java code to display lines number in jtextarea

提问by user2726811

I trying to write java code to pop up text area and if i add 9000 lines in jtextarea at right it display 9000 lines and vertical line.

我试图编写java代码来弹出文本区域，如果我在右边的jtextarea中添加9000行，它会显示9000行和垂直线。

Is there anyway that i can do it??

反正我能做到吗？？

Is there anyway that i can add line number like in pics..

无论如何我可以像图片中那样添加行号..

Please help me!! Thanks!!

请帮我！！谢谢！！

Here is my code:

这是我的代码：

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.LayoutManager;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.ScrollPaneConstants;
import javax.swing.text.DefaultCaret;


public class test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub


        final JFrame frame = new JFrame("Test");
        JPanel panel = new JPanel();
        panel.setLayout((LayoutManager) new BoxLayout(panel, BoxLayout.Y_AXIS));
        panel.setOpaque(true);
        final JTextArea textArea = new JTextArea(20, 30);
        textArea.setWrapStyleWord(true);
        textArea.setEditable(true);
        textArea.setFont(Font.getFont(Font.SANS_SERIF));
        JScrollPane scroller = new JScrollPane(textArea);
        scroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
        scroller.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);



        JPanel inputpanel = new JPanel();
        inputpanel.setLayout(new FlowLayout());

        JButton button = new JButton("Enter");
        DefaultCaret caret = (DefaultCaret) textArea.getCaret();
        caret.setUpdatePolicy(DefaultCaret.ALWAYS_UPDATE);
        panel.add(scroller);

        inputpanel.add(button);
        panel.add(inputpanel);
        frame.getContentPane().add(BorderLayout.CENTER, panel);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
        frame.setResizable(false);


        button.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {

            frame.dispose();
        }});
        frame.setSize(500, 400);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);   


    }

}

Please help me!! Thanks!!

请帮我！！谢谢！！

采纳答案by camickr

See Text Component Line Numberfor a component that can be used as a row header of the scrollpane that contains your text area.

有关可用作包含文本区域的滚动窗格的行标题的组件，请参阅文本组件行号。

回答by Ms_Joe

You need something like this maybe.Took the link from camickr.

也许你需要这样的东西。从camickr获取链接。

Add the class TextLineNumber from this link in the working folder: Click here!

在工作文件夹中从此链接添加类 TextLineNumber：单击此处！

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.border.EmptyBorder;
import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
import javax.swing.JTextArea;
import javax.swing.JLabel;
import javax.swing.LayoutStyle.ComponentPlacement;
import java.awt.Font;

public class TextLine extends JFrame {

    private JPanel contentPane;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    TextLine frame = new TextLine();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public TextLine() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 540, 425);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);

        JTextArea textArea = new JTextArea();
        JScrollPane pane1 = new JScrollPane(textArea, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
                JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
        TextLineNumber tln1 = new TextLineNumber(textArea);
        pane1.setRowHeaderView(tln1);
        contentPane.add(pane1, null);

        JLabel lblNewLabel = new JLabel("                 Text Line Example");
        lblNewLabel.setFont(new Font("Tahoma", Font.PLAIN, 18));
        GroupLayout gl_contentPane = new GroupLayout(contentPane);
        gl_contentPane.setHorizontalGroup(gl_contentPane.createParallelGroup(Alignment.LEADING).addGroup(
                gl_contentPane
                        .createSequentialGroup()
                        .addContainerGap(88, Short.MAX_VALUE)
                        .addGroup(
                                gl_contentPane
                                        .createParallelGroup(Alignment.LEADING)
                                        .addGroup(
                                                Alignment.TRAILING,
                                                gl_contentPane
                                                        .createSequentialGroup()
                                                        .addComponent(pane1, GroupLayout.PREFERRED_SIZE, 383,
                                                                GroupLayout.PREFERRED_SIZE).addGap(43))
                                        .addGroup(
                                                Alignment.TRAILING,
                                                gl_contentPane
                                                        .createSequentialGroup()
                                                        .addComponent(lblNewLabel, GroupLayout.PREFERRED_SIZE, 333,
                                                                GroupLayout.PREFERRED_SIZE).addGap(72)))));
        gl_contentPane.setVerticalGroup(gl_contentPane.createParallelGroup(Alignment.LEADING).addGroup(
                Alignment.TRAILING,
                gl_contentPane.createSequentialGroup()
                        .addComponent(lblNewLabel, GroupLayout.PREFERRED_SIZE, 51, GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(ComponentPlacement.RELATED, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addComponent(pane1, GroupLayout.PREFERRED_SIZE, 278, GroupLayout.PREFERRED_SIZE).addGap(42)));
        contentPane.setLayout(gl_contentPane);
    }
}

The working class:

工薪阶层：

http://img28.imageshack.us/img28/3731/vm6p.png

http://img28.imageshack.us/img28/3731/vm6p.png

回答by BullyWiiPlaza

Here's code based on the post from herebut fixed e.g. using efficient String concatenation to avoid lag when holding down the ENTERkey for example.

这是基于此处帖子的代码，但已修复例如使用有效的字符串连接以避免在按住ENTER键时出现延迟。

import javax.swing.*;
import javax.swing.text.Element;
import java.awt.*;

public class LineNumberingTextArea extends JTextArea
{
    private JTextArea textArea;

    public LineNumberingTextArea(JTextArea textArea)
    {
        this.textArea = textArea;
        setBackground(Color.LIGHT_GRAY);
        setEditable(false);
    }

    public void updateLineNumbers()
    {
        String lineNumbersText = getLineNumbersText();
        setText(lineNumbersText);
    }

    private String getLineNumbersText()
    {
        int caretPosition = textArea.getDocument().getLength();
        Element root = textArea.getDocument().getDefaultRootElement();
        StringBuilder lineNumbersTextBuilder = new StringBuilder();
        lineNumbersTextBuilder.append("1").append(System.lineSeparator());

        for (int elementIndex = 2; elementIndex < root.getElementIndex(caretPosition) + 2; elementIndex++)
        {
            lineNumbersTextBuilder.append(elementIndex).append(System.lineSeparator());
        }

        return lineNumbersTextBuilder.toString();
    }
}

In your GUI class, simply instantiate LineNumberTextAreaand give it the JTextAreainstance to attach to. Also set the JScrollPane's rowHeaderViewto the LineNumberingTextAreainstance:

在您的 GUI 类中，只需实例化LineNumberTextArea并为其提供JTextArea要附加的实例。还将JScrollPane'srowHeaderView设置为LineNumberingTextArea实例：

LineNumberingTextArea lineNumberingTextArea = new LineNumberingTextArea(myTextArea);
myTextAreaScrollPane.setRowHeaderView(lineNumberingTextArea);

Finally add a DocumentListenerfor your JTextAreato update the line numbers when the document changes:

最后添加一个DocumentListener供您JTextArea在文档更改时更新行号：

myTextArea.getDocument().addDocumentListener(new DocumentListener()
{
    @Override
    public void insertUpdate(DocumentEvent documentEvent)
    {
        lineNumberingTextArea.updateLineNumbers();
    }

    @Override
    public void removeUpdate(DocumentEvent documentEvent)
    {
        lineNumberingTextArea.updateLineNumbers();
    }

    @Override
    public void changedUpdate(DocumentEvent documentEvent)
    {
        lineNumberingTextArea.updateLineNumbers();
    }
});

回答by Dominique

In a JScrollPane, the vertical scrollbar doesn't work correctly with a component TextLineNumber. In order to correct this problem (and another problem of displaying), I modified the class TextLineNumberinto JTextLineNumber. In this new class, the text component class is JTextPanebut you can change it for JTextComponent. To use it, put your JTextLineNumbercomponent into a panel (with a border layout) at WEST and your text component at CENTER. Finally put this panel into a scroll pane.

在JScrollPane 中，垂直滚动条不能与组件TextLineNumber一起正常工作。为了更正这个问题（以及另一个显示问题），我将类TextLineNumber修改为JTextLineNumber。在这个新类中，文本组件类是JTextPane但您可以将其更改为JTextComponent。要使用它，请将您的JTextLineNumber组件放入位于 WEST 的面板（带有边框布局）和位于 CENTER 的文本组件。最后将此面板放入滚动窗格中。

I hope that it will help somebody.

我希望它会帮助某人。

The class JTextLineNumber:

JTextLineNumber类：

import java.awt.*;
import java.beans.*;
import java.util.HashMap;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;

/**
 * This class will display line numbers for a related text component. The text     component must use the same line height for each line. TextLineNumber supports wrapped lines and will highlight the line number of the current line in the text component.
 *
 * This class was designed to be used as a component added to the row header of a     JScrollPane.
 */
public class JTextLineNumber extends JPanel implements CaretListener, DocumentListener, PropertyChangeListener
{
 private static final long serialVersionUID = 1L;
public final static float                LEFT     = 0.0f;
public final static float                CENTER = 0.5f;
public final static float                RIGHT  = 1.0f;


// Text component this TextTextLineNumber component is in sync with

private JTextPane            component;

// Properties that can be changed

private boolean                          updateFont;
private int                                  borderGap;
private Color                                currentLineForeground;
private float                                digitAlignment;
private int                                  minimumDisplayDigits;

// Keep history information to reduce the number of times the component
// needs to be repainted

private int                                  lastDigits;
private int                                  lastHeight;
private int                                  lastLine;

private HashMap<String, FontMetrics> fonts;

/**
 * Create a line number component for a text component. This minimum display width will be based on 3 digits.
 *
 * @param component
 *           the related text component
 */
public JTextLineNumber(JTextPane component)
{
    this(component, 3);
}

/**
 * Create a line number component for a text component.
 *
 * @param component
 *           the related text component
 * @param minimumDisplayDigits
 *           the number of digits used to calculate the minimum width of the component
 */
public JTextLineNumber(JTextPane component,
                       int minimumDisplayDigits)
{
    this.component = component;
    setBorder(null);

    //setFont(component.getFont());

    setBorder(null);
    setBorderGap(5);
    setCurrentLineForeground(Color.BLACK);
    setDigitAlignment(RIGHT);
    setMinimumDisplayDigits(minimumDisplayDigits);

    component.getDocument().addDocumentListener(this);
    component.addCaretListener(this);
    component.addPropertyChangeListener("font", this);
}

/**
 * Gets the update font property
 *
 * @return the update font property
 */
public boolean getUpdateFont()
{
    return updateFont;
}

/**
 * Set the update font property. Indicates whether this Font should be updated automatically when the Font of the related text component is changed.
 *
 * @param updateFont
 *           when true update the Font and repaint the line numbers, otherwise just repaint the line numbers.
 */
public void setUpdateFont(boolean updateFont)
{
    this.updateFont = updateFont;
}

/**
 * Gets the border gap
 *
 * @return the border gap in pixels
 */
public int getBorderGap()
{
    return borderGap;
}

/**
 * The border gap is used in calculating the left and right insets of the border. Default value is 5.
 *
 * @param borderGap
 *           the gap in pixels
 */
public void setBorderGap(int borderGap)
{
    this.borderGap = borderGap;
    lastDigits = 0;
    setPreferredWidth();
}

/**
 * Gets the current line rendering Color
 *
 * @return the Color used to render the current line number
 */
public Color getCurrentLineForeground()
{
    return currentLineForeground == null ? getForeground() : currentLineForeground;
}

/**
 * The Color used to render the current line digits. Default is Coolor.RED.
 *
 * @param currentLineForeground
 *           the Color used to render the current line
 */
public void setCurrentLineForeground(Color currentLineForeground)
{
    this.currentLineForeground = currentLineForeground;
}

/**
 * Gets the digit alignment
 *
 * @return the alignment of the painted digits
 */
public float getDigitAlignment()
{
    return digitAlignment;
}

/**
 * Specify the horizontal alignment of the digits within the component. Common values would be:
 * <ul>
 * <li>TextLineNumber.LEFT
 * <li>TextLineNumber.CENTER
 * <li>TextLineNumber.RIGHT (default)
 * </ul>
 * 
 * @param currentLineForeground
 *           the Color used to render the current line
 */
public void setDigitAlignment(float digitAlignment)
{
    this.digitAlignment = digitAlignment > 1.0f ? 1.0f : digitAlignment < 0.0f ? -1.0f : digitAlignment;
}

/**
 * Gets the minimum display digits
 *
 * @return the minimum display digits
 */
public int getMinimumDisplayDigits()
{
    return minimumDisplayDigits;
}

/**
 * Specify the mimimum number of digits used to calculate the preferred width of the component. Default is 3.
 *
 * @param minimumDisplayDigits
 *           the number digits used in the preferred width calculation
 */
public void setMinimumDisplayDigits(int minimumDisplayDigits)
{
    this.minimumDisplayDigits = minimumDisplayDigits;
    setPreferredWidth();
}

/**
 * Calculate the width needed to display the maximum line number
 */
private void setPreferredWidth()
{
    // Define the font to display the numbers.
    Font componentFont = component.getFont();
    Font font = new Font(componentFont.getFamily(), Font.BOLD, componentFont.getSize());

    Element root = component.getDocument().getDefaultRootElement();
    int lines = root.getElementCount();
    int digits = Math.max(String.valueOf(lines).length(), minimumDisplayDigits);

    // Update sizes when number of digits in the line number changes

    if (lastDigits != digits)
    {
        lastDigits = digits;
        FontMetrics fontMetrics = getFontMetrics(font);
        int iPreferredWidth = 0;

        if (digits <= 1)
        {
            iPreferredWidth = 10 + fontMetrics.stringWidth("0");
        } else if (digits == 2)
        {
            iPreferredWidth = 10 + fontMetrics.stringWidth("00");
        } else if (digits == 3)
        {
            iPreferredWidth = 10 + fontMetrics.stringWidth("000");
        } else if (digits == 4)
        {
            iPreferredWidth = 10 + fontMetrics.stringWidth("0000");
        } else if (digits == 5)
        {
            iPreferredWidth = 10 + fontMetrics.stringWidth("00000");
        } else if (digits == 6)
        {
            iPreferredWidth = 10 + fontMetrics.stringWidth("000000");
        } else if (digits == 7)
        {
            iPreferredWidth = 10 + fontMetrics.stringWidth("0000000");
        } else 
        {
            iPreferredWidth = 10 + fontMetrics.stringWidth("00000000");
        }

        Dimension dimension = new Dimension(iPreferredWidth, 0);
        setPreferredSize(dimension);
        setSize(dimension);
    }
}

/**
 * Draw the line numbers
 */
@Override
public void paintComponent(Graphics g)
{
    // Paint the background.
    Graphics2D g2d = (Graphics2D)g;
    g2d.setColor(component.getBackground());
    g2d.fillRect(0, 0, getWidth(), getHeight());
    // Paint a vertical line at right.
    g2d.setStroke(new BasicStroke(1));
    g2d.setColor(new Color(0, 0, 0, 64));
    g2d.drawLine(getWidth() - 1, 0, getWidth() - 1, getHeight());
    // Define the font.
    Font componentFont = component.getFont();
    Font font = new Font(componentFont.getFamily(), Font.BOLD, componentFont.getSize());

    // Determine the width of the space available to draw the line number

    FontMetrics fontMetrics = component.getFontMetrics(component.getFont());
    int iRightAlignement = getSize().width - 5;

    // Determine the rows to draw within the clipped bounds.

    Rectangle clip = g.getClipBounds();
    int rowStartOffset = component.viewToModel(new Point(0, clip.y));
    int endOffset = component.viewToModel(new Point(0, clip.y + clip.height));
    g2d.setFont(font);

    while (rowStartOffset <= endOffset)
    {
        try
        {
            if (isCurrentLine(rowStartOffset))
                g2d.setColor(new Color(0, 0, 0, 160));
            else
                g2d.setColor(new Color(0, 0, 0, 100));

            // Get the line number as a string and then determine the
            // "X" and "Y" offsets for drawing the string.

            String lineNumber = getTextLineNumber(rowStartOffset);
            int stringWidth = ((Graphics2D)g).getFontMetrics().stringWidth(lineNumber);
            int iX = iRightAlignement - stringWidth;
            int iY = getOffsetY(rowStartOffset, fontMetrics);
            g2d.drawString(lineNumber, iX, iY);

            // Move to the next row

            rowStartOffset = Utilities.getRowEnd(component, rowStartOffset) + 1;
        } catch (Exception e)
        {
            break;
        }
    }
}

/*
 * We need to know if the caret is currently positioned on the line we are about to paint so the line number can be highlighted.
 */
private boolean isCurrentLine(int rowStartOffset)
{
    int caretPosition = component.getCaretPosition();
    Element root = component.getDocument().getDefaultRootElement();

    if (root.getElementIndex(rowStartOffset) == root.getElementIndex(caretPosition))
        return true;
    else
        return false;
}

/*
 * Get the line number to be drawn. The empty string will be returned when a line of text has wrapped.
 */
protected String getTextLineNumber(int rowStartOffset)
{
    Element root = component.getDocument().getDefaultRootElement();
    int index = root.getElementIndex(rowStartOffset);
    Element line = root.getElement(index);

    if (line.getStartOffset() == rowStartOffset)
        return String.valueOf(index + 1);
    else
        return "";
}

/*
 * Determine the Y offset for the current row
 */
private int getOffsetY(int rowStartOffset,
                       FontMetrics fontMetrics)
         throws BadLocationException
{
    // Get the bounding rectangle of the row

    Rectangle r = component.modelToView(rowStartOffset);
    int lineHeight = fontMetrics.getHeight();
    int y = r.y + r.height;
    int descent = 0;

    // The text needs to be positioned above the bottom of the bounding
    // rectangle based on the descent of the font(s) contained on the row.

    if (r.height == lineHeight) // default font is being used
    {
        descent = fontMetrics.getDescent();
    } else // We need to check all the attributes for font changes
    {
        if (fonts == null)
            fonts = new HashMap<String, FontMetrics>();

        Element root = component.getDocument().getDefaultRootElement();
        int index = root.getElementIndex(rowStartOffset);
        Element line = root.getElement(index);

        for (int i = 0; i < line.getElementCount(); i++)
        {
            Element child = line.getElement(i);
            AttributeSet as = child.getAttributes();
            String fontFamily = (String) as.getAttribute(StyleConstants.FontFamily);
            Integer fontSize = (Integer) as.getAttribute(StyleConstants.FontSize);
            String key = fontFamily + fontSize;

            FontMetrics fm = fonts.get(key);

            if (fm == null)
            {
                Font font = new Font(fontFamily, Font.PLAIN, fontSize);
                fm = component.getFontMetrics(font);
                fonts.put(key, fm);
            }

            descent = Math.max(descent, fm.getDescent());
        }
    }

    return y - descent;
}

//
// Implement CaretListener interface
//
@Override
public void caretUpdate(CaretEvent e)
{
    // Get the line the caret is positioned on

    int caretPosition = component.getCaretPosition();
    Element root = component.getDocument().getDefaultRootElement();
    int currentLine = root.getElementIndex(caretPosition);

    // Need to repaint so the correct line number can be highlighted

    if (lastLine != currentLine)
    {
        repaint();
        lastLine = currentLine;
    }
}

//
// Implement DocumentListener interface
//
@Override
public void changedUpdate(DocumentEvent e)
{
    documentChanged();
}

@Override
public void insertUpdate(DocumentEvent e)
{
    documentChanged();
}

@Override
public void removeUpdate(DocumentEvent e)
{
    documentChanged();
}

/*
 * A document change may affect the number of displayed lines of text. Therefore the lines numbers will also change.
 */
private void documentChanged()
{
    // View of the component has not been updated at the time
    // the DocumentEvent is fired

    SwingUtilities.invokeLater(new Runnable()
    {
        @Override
        public void run()
        {
            try
            {
                int endPos = component.getDocument().getLength();
                Rectangle rect = component.modelToView(endPos);

                if (rect != null && rect.y != lastHeight)
                {
                    setPreferredWidth();
                    repaint();
                    lastHeight = rect.y;
                }
            } catch (BadLocationException ex)
            {
                /* nothing to do */ }
        }
    });
}

//
// Implement PropertyChangeListener interface
//
@Override
public void propertyChange(PropertyChangeEvent evt)
{
    if (evt.getNewValue() instanceof Font)
    {
        if (updateFont)
        {
            Font newFont = (Font) evt.getNewValue();
            setFont(newFont);
            lastDigits = 0;
            setPreferredWidth();
        } else
        {
            repaint();
        }
    }
}
}