Question

我创建了一个textarea，我需要在必要时将一个滚动条应用到textarea（当文本太长而且无法再读取时）。

这是我编写的代码，但出于某种原因，滚动条真的没有出现？

    final JTextArea textArea = new JTextArea();
    textArea.setEditable(false);
    textArea.setBounds(10, 152, 456, 255);
    textArea.setBorder(border);
    textArea.setLineWrap(true);
    sbrText = new JScrollPane(textArea);
    sbrText.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
    panel_1.add(textArea);

Answer 1

由于使用JTextArea，您必须删除使setBounds()在屏幕上具有绝对大小的代码行。这使得不可调整大小，JScrollPane仅在其内容可调整大小时才有效。
```
// wrong
textArea.setBounds(10, 152, 456, 255);
```
请阅读JTextArea和JScrollPane教程;请从两个教程中运行示例。

Answer 2

看到这个

 import javax.swing.*;

    public class TestFrame extends JFrame

{
    JTextAreaWithScroll textArea;

    public TestFrame ()
    {
        super ("Test Frame");

        setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
        setSize (300, 300);

        textArea = new JTextAreaWithScroll (JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
                                            JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);

        add (textArea.getScrollPane ());
    }

    public static void main (String[] args)
    {
        SwingUtilities.invokeLater (new Runnable()
        {
            public void run ()
            {
                TestFrame f = new TestFrame ();
                f.setVisible (true);
            }
        });
    }
}


class JTextAreaWithScroll extends JTextArea
{
    private JScrollPane scrollPane;

    public JTextAreaWithScroll (int vsbPolicy, int hsbPolicy)
    {
        scrollPane = new JScrollPane (this, vsbPolicy, hsbPolicy);
    }

    public JScrollPane getScrollPane ()
    {
        return scrollPane;
    }
}

这 http://forum.html.it/forum/showthread/t-1035892.html

Answer 3

您将TextArea添加到父级两次（scrollPane和面板）。将最后一行更改为

panel_1.add(sbrText);

Answer 4

确保<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script> <div ng-app="myapp" ng-controller="myctrl"> <p>{{ foo }}</p> <div ng-show="true"> $scope.true is equal to false here. ng-show should hide this. </div> <div ng-show="true2"> $scope.true2 is equal to false here. ng-show hides this. </div> <div ng-hide="false"> $scope.false is equal to true here. ng-hide should hide this. </div> <div ng-hide="false2"> $scope.false2 is equal to true here. ng-hide hides this. </div> <div ng-hide="undefined"> $scope.undefined is equal to true here. ng-hide should hide this. </div> <div ng-hide="undefined2"> $scope.undefined2 is equal to true here. ng-hide hides this. </div> </div>和preferredSize相同。滚动窗格将使用viewportSize的首选大小调整自身大小，如果文本区域的首选大小足以显示自身，则可能导致滚动条消失。

再次，请阅读JTextArea和JScrollPane教程。

textArea

Java Textarea ScrollPane

4 个答案: