带有条纹背景的JTable [英] JTable with striped background

问题描述

对奇数行和偶数行使用不同的背景颜色是提高大表可读性的常用技巧。

Using a different background color for odd and even rows is a commonly used trick to improve readability of large tables.

我想在Swing的JTable中使用这个效果。我开始创建一个自定义表格渲染器，但这只能用于绘制实际单元格，我还想在表格的白色部分添加条纹，可能没有单元格。我可以子类化JTable并覆盖paintComponent（），但我更喜欢一个选项，我只能更改表的渲染。

I want to use this effect in Swing's JTable. I started out by creating a custom table renderer, but this can only be used to paint actual cells, and I also want to add stripes to the "white" part of the table where there might be no cells. I can subclass JTable and override paintComponent(), but I would prefer an option where I can just change the table's rendering.

有没有更好的方法呢？

编辑：根据目前的答案，如果不延长JTable，这似乎是不可能的。但是，当我覆盖JTable.paintComponent（）时，也只绘制有行的区域。我怎么画其余的？

According to the answers so far this seems to be impossible without extending JTable. However, when I override JTable.paintComponent() it also only paints the area where there are rows. How can I paint the rest?

推荐答案

使用 getCellRect（getRowCount（） - 1,0，true ）.y 获取空白的顶部y坐标，然后用 paintComponent（Graphics g）绘制一些Rectangles和（Grid-）行。

Use getCellRect( getRowCount() - 1, 0, true ).y to get the top y-coordinate of the empty space, and then paint some Rectangles and (Grid-)Lines with paintComponent( Graphics g ).

为了让您更轻松，这是一个很长（但完整）的解决方案; - ）

To make it much easier for you, here's a long (but complete) solution ;-)

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Rectangle;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.table.TableCellRenderer;
import javax.swing.table.TableColumn;

public class StripedEvenInWhitePartsTable extends JTable
{

  public StripedEvenInWhitePartsTable( String[][] data, String[] fields )
  {
    super( data, fields );
    setFillsViewportHeight( true ); //to show the empty space of the table 
  }


  @Override
  public void paintComponent( Graphics g )
  {
    super.paintComponent( g );

    paintEmptyRows( g );
  }


  public void paintEmptyRows( Graphics g )
  {
    Graphics newGraphics = g.create();
    newGraphics.setColor( UIManager.getColor( "Table.gridColor" ) );

    Rectangle rectOfLastRow = getCellRect( getRowCount() - 1, 0, true );
    int firstNonExistentRowY = rectOfLastRow.y; //the top Y-coordinate of the first empty tablerow

    if ( getVisibleRect().height > firstNonExistentRowY ) //only paint the grid if empty space is visible
    {
      //fill the rows alternating and paint the row-lines:
      int rowYToDraw = (firstNonExistentRowY - 1) + getRowHeight(); //minus 1 otherwise the first empty row is one pixel to high
      int actualRow = getRowCount() - 1; //to continue the stripes from the area with table-data

      while ( rowYToDraw < getHeight() )
      {
        if ( actualRow % 2 == 0 )
        {
          newGraphics.setColor( Color.ORANGE ); //change this to another color (Color.YELLOW, anyone?) to show that only the free space is painted
          newGraphics.fillRect( 0, rowYToDraw, getWidth(), getRowHeight() );
          newGraphics.setColor( UIManager.getColor( "Table.gridColor" ) );
        }

        newGraphics.drawLine( 0, rowYToDraw, getWidth(), rowYToDraw );

        rowYToDraw += getRowHeight();
        actualRow++;
      }


      //paint the column-lines:
      int x = 0;
      for ( int i = 0; i < getColumnCount(); i++ )
      {
        TableColumn column = getColumnModel().getColumn( i );
        x += column.getWidth(); //add the column width to the x-coordinate

        newGraphics.drawLine( x - 1, firstNonExistentRowY, x - 1, getHeight() );
      }

      newGraphics.dispose();

    } //if empty space is visible

  } //paintEmptyRows



  public Component prepareRenderer( TableCellRenderer renderer, int row, int column )
  {
    Component c = super.prepareRenderer( renderer, row, column );

    if ( !isRowSelected( row ) )
    {
      c.setBackground( row % 2 == 0 ? getBackground() : Color.ORANGE );
    }

    return c;
  }


  public static void main( String[] argv )
  {
    String data[][] = { { "A0", "B0", "C0" }, { "A1", "B1", "C1" }, { "A2", "B2", "C2" }, { "A3", "B3", "C3" }, { "A4", "B4", "C4" } };
    String fields[] = { "A", "B", "C" };

    JFrame frame = new JFrame( "a JTable with striped empty space" );
    StripedEvenInWhitePartsTable table = new StripedEvenInWhitePartsTable( data, fields );
    JScrollPane pane = new JScrollPane( table );

    frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
    frame.add( pane );
    frame.setSize( 400, 300 );
    frame.setLocationRelativeTo( null );
    frame.setVisible( true );
  }

}

这个例子可以扩展到：

This example could be extended to:

• 为变量RowHeights修复绘制的伪网格（我使用的是任何行中使用的最低高度）


• 向用户解释为什么没有任何反应，如果他点击空白区域来编辑单元格（通过工具提示）


• 如果用户点击了表格模型，请在表格模型中添加一行空的空间（nooo！请不要Excel！）


• 使用空白空间绘制表格的反映（包括所有渲染数据（用于？;-)）

• fix the painted pseudogrid for variable RowHeights (I'm using the lowest height used in any row)
• explain to the user why nothing happens if he clicks in the empty space to edit the cells (via tooltip)
• add an extra row to the table model if the user clicks in the empty space (nooo! no Excel please!)
• use the empty space to draw a reflection of the table (including all rendered data ( what for? ;-) )

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