java - JScrollPane 不会滚动到 JTable 的底部

Question

我有一个显示 JTable 的 JScrollPane，并且 JTable 具有不同的行高，具体取决于此自定义定义的每个单元格中需要容纳文本的行数

DefaultTableCellRenderer renderer = new DefaultTableCellRenderer() {

    public Component getTableCellRendererComponent (JTable table, 
                Object obj, boolean isSelected, boolean hasFocus, int row, int column) {

            Component rendererComp = super.getTableCellRendererComponent(table, obj, isSelected, hasFocus,
                    row, column);
            if(column == 5) {
                JTextArea text = new JTextArea(obj.toString());
                text.setFont(rendererComp.getFont());
                text.setLineWrap(true);
                text.setWrapStyleWord(true);
                text.setSize(new Dimension(
                        moves.getColumnModel().getColumn(column).getWidth(),
                        9999999));
                text.setSize(text.getSize().width, text.getPreferredSize().height);
                table.setRowHeight(row, text.getPreferredSize().height);
                return text;
            } else 
                return rendererComp;
        }
    };

只有第五列才有文本区域，因为只有第五列可以有足够的文本来需要多行。

我包含此内容的原因是，在添加此渲染器之前，JScrollPane 工作正常，但这需要是单元格渲染器，否则 JTable 中的某些信息根本不会显示。它可以很好地以正确的高度创建行。然而，JTable 的 PreferredSize 显然计算不正确(我确信它不是，我搞砸了一些东西，但看起来就是这样)，因为现在 JScrollPane 不会一直滚动到底部。当我在为每列设置单元格渲染器后对 JTable 中的每一行调用 getRowHeight 时，它们都返回 16，尽管 JTable 中很明显存在具有不同高度的行。目前该表的外观如下:

正如您所看到的，应该显示下一行的一小部分，但不能显示，因为滚动条实际上​​并没有一直向下滚动到表格。我已经设置了 JTable 和 JScrollPane 的首选大小，甚至通过向 JTable 首选大小的高度添加任意常量来显示整个表格，但程序需要能够计算正确的值根据表中的信息确定尺寸。我只想知道如何在 JScrollPane 中准确显示整个 JTable。如果看到代码的任何其他部分可以帮助我知道，很抱歉没有首先发布它。

Answer 1

我对发布的渲染器没有任何问题。您可以在底部查看我的代码。我能建议的是

• 请勿将尺寸设置为任何内容。学习使用布局管理器并打包框架，以便尊重所有首选尺寸。

• 即使在渲染器中，也不要设置 JTextArea 的大小，而是使用此构造函数

  JTexArea(String text, int rows, int columns)
  

• 不要使用空布局。我也遇到过类似的问题，有人试图在 table 上设置界限。

<小时/>

import java.awt.Component;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableCellRenderer;

public class Test {

    public Test() {
        String[][] data = {
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"},
            {"sdvjdnvdfjvnsdvsdjvs", "sdvjdnvdfjvnsdvsdjvsdvkdsjvnbdvlkjvnbdkvdvkdjvvsnvlkdnv"}};

        String[] cols = {"COL 1", "COL 2"};

        final JTable moves = new JTable(data, cols);

        DefaultTableCellRenderer renderer = new DefaultTableCellRenderer() {

            public Component getTableCellRendererComponent(JTable table,
                    Object obj, boolean isSelected, boolean hasFocus, int row, int column) {

                Component rendererComp = super.getTableCellRendererComponent(table, obj, isSelected, hasFocus,
                        row, column);
                if (column == 1) {
                    JTextArea text = new JTextArea(obj.toString(), 2, 20);
                    text.setFont(rendererComp.getFont());
                    text.setLineWrap(true);
                    text.setWrapStyleWord(true);
                    text.setSize(text.getSize().width, text.getPreferredSize().height);
                    table.setRowHeight(row, text.getPreferredSize().height);
                    return text;
                } else {
                    return rendererComp;
                }
            }
        };

        moves.setDefaultRenderer(Object.class, renderer);

        JFrame frame = new JFrame();
        frame.add(new JScrollPane(moves));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                Test test = new Test();
            }
        });
    }
}