JTable右对齐页眉

基本上，我有一个JTable，它包含右对齐单元格但左对齐标题的列，这看起来真的很糟糕。我想右对齐这些列的标题，而不改变标题的"外观"。

感谢

这里有一种修改表的JTableHeader的TableCellRenderer的替代方法。对于这种用法来说，这并不是绝对必要的，但它最大限度地减少了对UI代理外观的影响。

典型用法：

JTable table = new JTable(…);
JTableHeader header = table.getTableHeader();
header.setDefaultRenderer(new HeaderRenderer(table));

自定义标头渲染器：

private static class HeaderRenderer implements TableCellRenderer {
    DefaultTableCellRenderer renderer;
    public HeaderRenderer(JTable table) {
        renderer = (DefaultTableCellRenderer)
            table.getTableHeader().getDefaultRenderer();
        renderer.setHorizontalAlignment(JLabel.CENTER);
    }
    @Override
    public Component getTableCellRendererComponent(
        JTable table, Object value, boolean isSelected,
        boolean hasFocus, int row, int col) {
        return renderer.getTableCellRendererComponent(
            table, value, isSelected, hasFocus, row, col);
    }
}

试试这个：

((DefaultTableCellRenderer)table.getTableHeader().getDefaultRenderer())
    .setHorizontalAlignment(JLabel.RIGHT);

DefaultTableCellRenderer renderer = (DefaultTableCellRenderer) your_jtable.getTableHeader().getDefaultRenderer();
renderer.setHorizontalAlignment(0);

其中0为中心。

上面显示的HeaderRenderer(2011/sp/21由trashgod提供(与Heisenbug(2011/spp/21(的代码相结合，只有在所有标头都对齐的情况下才能正常工作。

如果你想以不同的方式排列不同的标题，那么你必须使用以下代码：

int[] alignments = new int[] { JLabel.LEFT, JLabel.RIGHT, JLabel.RIGHT };
for (int i = 0 ; i < jTable.getColumnCount(); i++){
  jTable.getTableHeader().getColumnModel().getColumn(i)
    .setHeaderRenderer(new HeaderRenderer(jTable, alignments[i]));
}

和

private static class HeaderRenderer implements TableCellRenderer {
  DefaultTableCellRenderer renderer;
  int horAlignment;
  public HeaderRenderer(JTable table, int horizontalAlignment) {
    horAlignment = horizontalAlignment;
    renderer = (DefaultTableCellRenderer)table.getTableHeader()
        .getDefaultRenderer();
  }
  public Component getTableCellRendererComponent(JTable table, Object value,
      boolean isSelected, boolean hasFocus, int row, int col) {
    Component c = renderer.getTableCellRendererComponent(table, value,
      isSelected, hasFocus, row, col);
    JLabel label = (JLabel)c;
    label.setHorizontalAlignment(horAlignment);
    return label;
  }
}

即：
在getTableCellRendererComponent中设置对齐，而不是在HeaderRenderer构造函数中设置对齐。

包装默认表头需要记住的一点是：不要保留它们的引用。

如果你(或你的用户(在Windows7上使用Windows经典主题，而你的应用程序设置了默认系统LAF，@trashgod发布的答案可能会给你带来问题。

它受到这个十年前发布的错误的影响(严重(。如果您的表格正在显示，并且您将Windows首选项中的主题从Aero主题切换到Windows Classic，将会出现大量的NPE。您不应该保留渲染器的引用，因为它可能在某个时间点变得无效。包装应该以动态的方式完成，正如bug报告的注释中所建议的那样。我从那里获得了代码，并创建了以下可运行的示例：

import java.awt.*;
import java.lang.ref.WeakReference;
import javax.swing.*;
import javax.swing.table.*;
public class TestFrame extends JFrame {
    private static final boolean I_WANT_THE_BUG_TO_HAPPEN = true;
    public static void main(String[] args) throws IllegalAccessException, ClassNotFoundException, InstantiationException, UnsupportedLookAndFeelException {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                int res = JOptionPane.showConfirmDialog(null, "Do you want to use the XP L&F?", "laffo", JOptionPane.YES_NO_OPTION);
                if (res == JOptionPane.YES_OPTION) {
                    try {
                        UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
                    } catch (Exception ex) {
                    }
                }
                new TestFrame().setVisible(true);
            }
        });
    }
    public class MyModel extends AbstractTableModel {
        public int getRowCount() {
            return 10;
        }
        public int getColumnCount() {
            return 10;
        }
        public Object getValueAt(int rowIndex, int columnIndex) {
            return "" + rowIndex + " X " + columnIndex;
        }
    }
    public class MyJTable extends JTable {
        /**
         *
         */
        private static final long serialVersionUID = -233098459210523146L;
        public MyJTable(TableModel model) {
            super(model);
        }
        public void doSomething() {
            System.out.println("HEHE");
        }
    }
    public class MyAlternativeJTable extends JTable {
        private WeakReference<TableCellRenderer> wrappedHeaderRendererRef = null;
        private TableCellRenderer wrapperHeaderRenderer = null;
        public MyAlternativeJTable(TableModel model) {
            super(model);
        }
        private class MyAlternativeTableColumn extends TableColumn {
            MyAlternativeTableColumn(int modelIndex) {
                super(modelIndex);
            }
            @Override
            public TableCellRenderer getHeaderRenderer() {
                TableCellRenderer defaultHeaderRenderer
                        = MyAlternativeJTable.this.getTableHeader().getDefaultRenderer();
                if (wrappedHeaderRendererRef == null
                        || wrappedHeaderRendererRef.get() != defaultHeaderRenderer) {
                    wrappedHeaderRendererRef
                            = new WeakReference<TableCellRenderer>(defaultHeaderRenderer);
                    wrapperHeaderRenderer
                            = new DecoratedHeaderRenderer(defaultHeaderRenderer);
                }
                return wrapperHeaderRenderer;
            }
        }
        @Override
        public void createDefaultColumnsFromModel() {
            TableModel m = getModel();
            if (m != null) {
                // Remove any current columns
                TableColumnModel cm = getColumnModel();
                while (cm.getColumnCount() > 0) {
                    cm.removeColumn(cm.getColumn(0));
                }
                // Create new columns from the data model info
                for (int i = 0; i < m.getColumnCount(); i++) {
                    TableColumn newColumn = new MyAlternativeTableColumn(i);
                    addColumn(newColumn);
                }
            }
        }
    }
    private JPanel jContentPane = null;
    private JScrollPane jScrollPane = null;
    private JTable table1 = null;
    private JScrollPane jScrollPane1 = null;
    private JTable table2 = null;
    /**
     * This is the default constructor
     */
    public TestFrame() {
        super();
        initialize();
        int res = JOptionPane.showConfirmDialog(null, "Do you want to call updateUI() on the tables ?", "laffo", JOptionPane.YES_NO_OPTION);
        if (res == JOptionPane.YES_OPTION) {
            table2.updateUI();
            table1.updateUI();
        }
    }
    /**
     * This method initializes this
     *
     * @return void
     */
    private void initialize() {
        this.setSize(753, 658);
        this.setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);
        this.setContentPane(getJContentPane());
        this.setTitle("JFrame");
    }
    /**
     * This method initializes jContentPane
     *
     * @return javax.swing.JPanel
     */
    private JPanel getJContentPane() {
        if (jContentPane == null) {
            jContentPane = new JPanel();
            jContentPane.setLayout(null);
            jContentPane.add(getJScrollPane(), null);
            jContentPane.add(getJScrollPane1(), null);
        }
        return jContentPane;
    }
    /**
     * This method initializes jScrollPane
     *
     * @return javax.swing.JScrollPane
     */
    private JScrollPane getJScrollPane() {
        if (jScrollPane == null) {
            jScrollPane = new JScrollPane();
            jScrollPane.setBounds(new java.awt.Rectangle(358, 0, 387, 618));
            jScrollPane.setViewportView(getTable1());
        }
        return jScrollPane;
    }
    /**
     * This method initializes table1
     *
     * @return javax.swing.JTable
     */
    private JTable getTable1() {
        if (table1 == null) {
            table1 = new JTable(new MyModel());
        }
        return table1;
    }
    /**
     * This method initializes jScrollPane1
     *
     * @return javax.swing.JScrollPane
     */
    private JScrollPane getJScrollPane1() {
        if (jScrollPane1 == null) {
            jScrollPane1 = new JScrollPane();
            jScrollPane1.setBounds(new java.awt.Rectangle(0, 0, 350, 618));
            jScrollPane1.setViewportView(getTable2());
        }
        return jScrollPane1;
    }
    /**
     * This method initializes table2
     *
     * @return javax.swing.JTable
     */
    private JTable getTable2() {
        if (table2 == null) {
            if (I_WANT_THE_BUG_TO_HAPPEN) {
                table2 = new MyJTable(new MyModel());
                JTableHeader header = table2.getTableHeader();
                TableCellRenderer render = new DecoratedHeaderRenderer(header.getDefaultRenderer());
                header.setDefaultRenderer(render);
            } else {
                table2 = new MyAlternativeJTable(new MyModel());
            }
        }
        return table2;
    }
    private class DecoratedHeaderRenderer implements TableCellRenderer {
        public DecoratedHeaderRenderer(TableCellRenderer render) {
            this.render = render;
        }
        private TableCellRenderer render;
        public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {
            Component c = render.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
            return c;
        }
    }
}

只需运行该示例并选择Yes两次，然后看着它分解。然后将I_WANT_THE_BUG_TO_HAPPEN静态成员更改为false并重复。此成员设置为true的情况与此处投票最多的答案基本相同。这个例子中最重要的部分是扩展的JTable(MyAlternativeJTable(，它动态地进行包装。

目前公认的这个问题的答案被广泛使用，但这是不明智的。具有讽刺意味的是，您可以使用丢失的应用程序来复制它，包括Netbeans 8.0.2(它本身是基于Java的(，同时它显示一个可排序的表，如Window > IDE Tools > Notifications，您还可以在其中获得NPE报告。只需在Windows7上将Windows主题从Aero切换到Windows Classic(通过right-click Desktop > Personalize > Change the visuals and sounds on your computer(。

如果您正在使用Glazed Lists并调用ca.odell.glazedlists.swing.TableComparatorChooser.install，您也会受到影响。它注入了自己的自定义渲染器来对箭头进行排序。

我在试图找到这个问题的解决方案时偶然发现了这一点，我怀疑这个问题与此有关。

for (int i = 0 ; i < table.getColumnCount(); i++){
    DefaultTableCellRenderer renderer = new DefaultTableCellRenderer();
    renderer.setHorizontalAlignment(SwingConstants.RIGHT);
    table.getColumn(i).setHeaderRenderer(renderer);
}

DefaultTableCellRenderer renderer = (DefaultTableCellRenderer) 
MSISDNTable.getTableHeader().getDefaultRenderer();
renderer.setHorizontalAlignment(JLabel.RIGHT);

其中MSISDNTable是您的表

DefaultTableCellRenderer defaultHeaderRenderer = (DefaultTableCellRenderer) getTableHeader().getDefaultRenderer();
defaultHeaderRenderer.setHorizontalAlignment(JLabel.CENTER);         
getTableHeader().setDefaultRenderer(defaultHeaderRenderer);

我已经用JAVA8进行了测试。工作良好。

试试这个代码，

JTableHeader jtableHeader = jtable.getTableHeader();
DefaultTableCellRenderer rend = (DefaultTableCellRenderer) jtable.getTableHeader().getDefaultRenderer();
rend.setHorizontalAlignment(JLabel.CENTER);
jtableHeader.setDefaultRenderer(rend);

我已经创建了一个基于pvbemmelen62解决方案的类，它可以非常容易地使用，例如：

AlignHeaderRenderer.install(myTable, new int[] { SwingConstants.RIGHT,
                        SwingConstants.RIGHT, SwingConstants.LEFT });

或

AlignHeaderRenderer.install(myTable, 0, SwingConstants.RIGHT);
AlignHeaderRenderer.install(myTable, 1, SwingConstants.RIGHT);

这是代码：

public class AlignHeaderRenderer implements TableCellRenderer {
private final TableCellRenderer renderer;
private final int alignment;
public static void install(final JTable table, final int[] alignments) {
    for (int i = 0; i < alignments.length; ++i)
        install(table, i, alignments[i]);
}
public static void install(final JTable table, final int row,
        final int alignment) {
    table.getTableHeader().getColumnModel().getColumn(row)
            .setHeaderRenderer(new AlignHeaderRenderer(table, alignment));
}
private AlignHeaderRenderer(final JTable table, final int alignment) {
    renderer = table.getTableHeader().getDefaultRenderer();
    this.alignment = alignment;
}
@Override
public Component getTableCellRendererComponent(final JTable table,
        final Object value, final boolean isSelected,
        final boolean hasFocus, final int row, final int col) {
    final Component c = renderer.getTableCellRendererComponent(table,
            value, isSelected, hasFocus, row, col);
    ((JLabel) c).setHorizontalAlignment(alignment);
    return c;
}
}

秘密是使用伪表中的渲染器来获得正确的L&F、并从实际表的行渲染器复制对齐。这样，每列都是单独对齐的。这是代码：

table.getTableHeader().setDefaultRenderer(new DefaultTableCellRenderer() {
    @Override
    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int col) {
        Component c2 = dummy.getTableHeader().getDefaultRenderer().getTableCellRendererComponent(table, value, isSelected, hasFocus, row, col);
        if (table.getRowCount() > 0) {
            Component c3 = table.getCellRenderer(0, col).getTableCellRendererComponent(table, value, isSelected, hasFocus, 0, col);
            if (c2 instanceof JLabel && c3 instanceof JLabel)
                ((JLabel)c2).setHorizontalAlignment(((JLabel)c3).getHorizontalAlignment());
        }
        return c2;
    }
    private final JTable dummy = new JTable();
});

上面的代码没有保留对渲染器的任何引用，因此避免了上面提到的NPE错误。它不需要任何命名类，所以你可以把代码放在任何需要的地方

  ((DefaultTableCellRenderer)jTable2.getTableHeader().getDefaultRenderer())
    .setHorizontalAlignment(JLabel.CENTER);

((JLabel)mTabBOM.getTableHeader().getDefaultRenderer()).setHorizontalAlignment( JLabel.CENTER );

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