Question

在我的代码中，我正在尝试使用文本框创建滚动条。我有文本框但我无法滚动它。我一直在寻找新的解决方案，但它们都不起作用。如果你知道什么是错的可以帮助我

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.*;

public class Tutorial extends JFrame
{
  public static void main(String args)
  {
    JPanel jp = new JPanel();
    JLabel jl = new JLabel();
    JTextField jt = new JTextField("TYPE", 200);
    JScrollPane myScrollPane = new JScrollPane(jt); 
    JButton jb = new JButton("Enter");
  }

  public Tutorial()
  {
    setTitle("TextBox");
    setVisible(true);
    setSize(400,500);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    jt.setSize(300,400);
    jp.add(jt);
    jp.add(jb);

    add(jp);
  }
}

Answer 1

您需要将滚动窗格添加到框架中：

//jp.add(jt);
jp.add(myScrollPane);

您还需要确保水平滚动条始终可见，以便可以计算滚动窗格的正确高度。

此外，当您发布代码时，请确保发布可编译的代码。你发布的代码毫无意义，你甚至无法测试上面的代码。

Answer 2

这是一个完整的例子：

import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;

public class SamplePane extends JFrame  {

    private static final long serialVersionUID = -1775096938821736542L;

    public SamplePane() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(400,500);

        JPanel jp = new JPanel();
        JTextField jt = new JTextField("TYPE", 200);
        JScrollPane myScrollPane = new JScrollPane(jt); 
        jp.add(myScrollPane);

        setContentPane(myScrollPane);
    }


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

}

Answer 3

另一种选择是使用scroller.setModel(textField.getHorizontalVisibility());
- 此方法的优点是在选择文本（或右箭头键）时JScrollBar拇指滚动。
- 此方法的缺点是，如果删除了所有文本，则始终显示JScrollBar拇指。

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

public class HorizontalVisibilityTest {
  private static final boolean DEBUG = false;
  private static final String TEXT = "javascript:(function(){var l=location,"
                                     + "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa=0;}());";
  public JComponent makeUI() {
    Box box = Box.createVerticalBox();
    JScrollPane scroll = new JScrollPane(
      ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER,
      ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
    scroll.setViewportView(new JTextField(TEXT));
    box.add(new JLabel("JScrollPane + VERTICAL_SCROLLBAR_NEVER"));
    box.add(scroll);

    box.add(Box.createVerticalStrut(15));
    final JTextField textField = new JTextField(TEXT);
    JScrollBar scroller = new JScrollBar(JScrollBar.HORIZONTAL);
    scroller.setModel(textField.getHorizontalVisibility());

    if (DEBUG) { //I'm not sure if this is a bug...
      EmptyThumbHandler handler = new EmptyThumbHandler(textField, scroller);
      textField.addComponentListener(handler);
      textField.getDocument().addDocumentListener(handler);
    }

    box.add(new JLabel("BoundedRangeModel: textField.getHorizontalVisibility()"));
    box.add(textField, BorderLayout.SOUTH);
    box.add(Box.createVerticalStrut(5));
    box.add(scroller);

    JPanel p = new JPanel(new BorderLayout());
    p.add(box, BorderLayout.NORTH);
    p.setBorder(BorderFactory.createEmptyBorder(20, 5, 5, 5));
    return p;
  }
  public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
      @Override public void run() {
        createAndShowGUI();
      }
    });
  }
  public static void createAndShowGUI() {
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    f.getContentPane().add(new HorizontalVisibilityTest().makeUI());
    f.setSize(320, 240);
    f.setLocationRelativeTo(null);
    f.setVisible(true);
  }
}

// class EmptyThumbHandler extends ComponentAdapter implements DocumentListener {
//   private final BoundedRangeModel emptyThumbModel = new DefaultBoundedRangeModel(0, 1, 0, 1);
//   private final JTextField textField;
//   private final JScrollBar scroller;
//   public EmptyThumbHandler(JTextField textField, JScrollBar scroller) {
//     super();
//     this.textField = textField;
//     this.scroller = scroller;
//   }
//   private void changeThumbModel() {
//     EventQueue.invokeLater(new Runnable() {
//       @Override public void run() {
//         BoundedRangeModel m = textField.getHorizontalVisibility();
//         int i = m.getMaximum() - m.getMinimum() - m.getExtent() - 1; // -1: ?????
//         System.out.println(i);
//         if (i <= 0) {
//           scroller.setModel(emptyThumbModel);
//         } else {
//           scroller.setModel(textField.getHorizontalVisibility());
//         }
//       }
//     });
//   }
//   @Override public void componentResized(ComponentEvent e) {
//     changeThumbModel();
//   }
//   @Override public void insertUpdate(DocumentEvent e) {
//     changeThumbModel();
//   }
//   @Override public void removeUpdate(DocumentEvent e) {
//     changeThumbModel();
//   }
//   @Override public void changedUpdate(DocumentEvent e) {
//     changeThumbModel();
//   }
// }

如何让文本框滚动

3 个答案: