JTextField水平滚动Java Swing

Question

I have a JTextField inside a JPanel . The user can type text as big as she wants in the textfield , however horizontal scrolling should appear when the text goes beyond the screen of the textfield. At this point if the user backspace the text and shrink the text within the screen of the textfield , the scrolling should disappear. So basically scrolling should appear only when its needed. How to do it ? Help please.

Answer 1

If you don't like the behavior of the JScrollPane + JTextField , you need to use JScrollBar#setModel(BoundedRangeModel) + JTextField#getHorizontalVisibility() :

import java.awt.*;
import javax.swing.*;
import javax.swing.plaf.basic.BasicScrollBarUI;

public class TextFieldScrollBarTest {
  private static final String TEXT = "javascript:(function(){var l=location,m=l.href.match('^(https?://)(.+)(api[^+]+|technotes[^+]+)');if(m)l.href=m[1]+'docs.oracle.com/javase/8/docs/'+decodeURIComponent(m[3]).replace(/\\+.*$/,'').replace(/\\[\\]/g,':A').replace(/, |\\(|\\)/g,'-');}());";

  public JComponent makeUI() {
    JScrollPane scroll = new JScrollPane(new JTextField(TEXT));
    scroll.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);

    JTextField textField = new JTextField(TEXT);
    JScrollBar scroller = new JScrollBar(Adjustable.HORIZONTAL) {
      @Override public void updateUI() {
        //super.updateUI();
        setUI(new ArrowButtonlessScrollBarUI());
      }
      @Override public Dimension getPreferredSize() {
        Dimension d = super.getPreferredSize();
        d.height = 5;
        return d;
      }
    };
    scroller.setModel(textField.getHorizontalVisibility());

    Box box = Box.createVerticalBox();
    box.add(scroll);
    box.add(Box.createVerticalStrut(50));
    box.add(textField);
    box.add(Box.createVerticalStrut(2));
    box.add(scroller);
    box.add(Box.createVerticalGlue());

    JPanel p = new JPanel(new BorderLayout());
    p.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
    p.add(box, BorderLayout.NORTH);
    return p;
  }

  public static void main(String... args) {
    EventQueue.invokeLater(() -> {
      JFrame f = new JFrame();
      f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
      f.getContentPane().add(new TextFieldScrollBarTest().makeUI());
      f.setSize(320, 240);
      f.setLocationRelativeTo(null);
      f.setVisible(true);
    });
  }
}

class ZeroSizeButton extends JButton {
  private static final Dimension ZERO_SIZE = new Dimension();
  @Override public Dimension getPreferredSize() {
    return ZERO_SIZE;
  }
}

class ArrowButtonlessScrollBarUI extends BasicScrollBarUI {
  private static final Color DEFAULT_COLOR  = new Color(220, 100, 100);
  private static final Color DRAGGING_COLOR = new Color(200, 100, 100);
  private static final Color ROLLOVER_COLOR = new Color(255, 120, 100);
  @Override protected JButton createDecreaseButton(int orientation) {
    return new ZeroSizeButton();
  }
  @Override protected JButton createIncreaseButton(int orientation) {
    return new ZeroSizeButton();
  }
  @Override protected void paintTrack(Graphics g, JComponent c, Rectangle r) {
    //Graphics2D g2 = (Graphics2D) g.create();
    //g2.setPaint(new Color(100, 100, 100));
    //g2.fillRect(r.x, r.y, r.width - 1, r.height - 1);
    //g2.dispose();
  }
  @Override protected void paintThumb(Graphics g, JComponent c, Rectangle r) {
    JScrollBar sb = (JScrollBar) c;
    if (!sb.isEnabled()) {
      return;
    }
    BoundedRangeModel m = sb.getModel();
    int iv = m.getMaximum() - m.getMinimum() - m.getExtent() - 1; // -1: bug?
    if (iv > 0) {
      Graphics2D g2 = (Graphics2D) g.create();
      g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
      Color color;
      if (isDragging) {
        color = DRAGGING_COLOR;
      } else if (isThumbRollover()) {
        color = ROLLOVER_COLOR;
      } else {
        color = DEFAULT_COLOR;
      }
      g2.setPaint(color);
      g2.fillRect(r.x, r.y, r.width - 1, r.height - 1);
      g2.dispose();
    }
  }
}