Java:将滚动添加到文本区域

Question

如何将滚动条添加到文本区域.我试过这个代码,但它没有用.

            middlePanel=new JPanel();
        middlePanel.setBorder(new TitledBorder(new EtchedBorder(), "Display Area"));

        // create the middle panel components

        display = new JTextArea(16, 58);
        display.setEditable(false); // set textArea non-editable
        scroll = new JScrollPane(display);
        scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);

        //Add Textarea in to middle panel
        middlePanel.add(scroll);
        middlePanel.add(display);

谢谢

Answer 1

在这里将JTextArea添加到JScrollPane之后:

scroll = new JScrollPane(display);

您不需要像以下那样将其再次添加到其他容器中:

middlePanel.add(display);

只需删除最后一行代码,它就能正常工作.像这样:

    middlePanel=new JPanel();
    middlePanel.setBorder(new TitledBorder(new EtchedBorder(), "Display Area"));

    // create the middle panel components

    display = new JTextArea(16, 58);
    display.setEditable(false); // set textArea non-editable
    scroll = new JScrollPane(display);
    scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);

    //Add Textarea in to middle panel
    middlePanel.add(scroll);

JScrollPane只是另一个容器,它在需要时将滚动条放在组件周围,并且还有自己的布局.当你想把任何东西包装成一个滚动时你需要做的就是把它传递给JScrollPane构造函数:

new JScrollPane( myComponent ) 

或设置如下视图:

JScrollPane pane = new JScrollPane ();
pane.getViewport ().setView ( myComponent );

额外:

这是一个完全有效的例子,因为你仍然没有让它工作:

public static void main ( String[] args )
{
    JPanel middlePanel = new JPanel ();
    middlePanel.setBorder ( new TitledBorder ( new EtchedBorder (), "Display Area" ) );

    // create the middle panel components

    JTextArea display = new JTextArea ( 16, 58 );
    display.setEditable ( false ); // set textArea non-editable
    JScrollPane scroll = new JScrollPane ( display );
    scroll.setVerticalScrollBarPolicy ( ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS );

    //Add Textarea in to middle panel
    middlePanel.add ( scroll );

    // My code
    JFrame frame = new JFrame ();
    frame.add ( middlePanel );
    frame.pack ();
    frame.setLocationRelativeTo ( null );
    frame.setVisible ( true );
}

这是你得到的:

Answer 2

我天真的假设是滚动窗格的大小将自动确定...

实际上对我有用的唯一解决方案是明确地发布JScrollPane的边界:

import javax.swing.*;

public class MyFrame extends JFrame {

    public MyFrame()
    {
        setBounds(100, 100, 491, 310);
        getContentPane().setLayout(null);

        JTextArea textField = new JTextArea();
        textField.setEditable(false);

        String str = "";
        for (int i = 0; i < 50; ++i)
            str += "Some text\n";
        textField.setText(str);

        JScrollPane scroll = new JScrollPane(textField);
        scroll.setBounds(10, 11, 455, 249);                     // <-- THIS

        getContentPane().add(scroll);
        setLocationRelativeTo ( null );
    }
}

也许它会帮助一些未来的访客:)

Answer 3

尝试将这两行添加到您的代码中。我希望它会起作用。它对我有用:)

display.setLineWrap(true);
display.setWrapStyleWord(true);

输出图片如下所示