Oracle TableRenderDemo中的单元格/行格式化

Question

好吧，首先让我说，在相隔几年之后，我正在回归编程。同时事情发生了很大变化（IDE，OO），我开始第一次用Java编程。

我需要构建一个GUI前端，我目前正在与JTables，tableModels和Renderer一起苦苦挣扎。

我目前正在通过Oracle TableRenderDemo工作，试图准确了解它在做什么以及是否有点卡住。

我怀疑我可能会加入到这个职位，但现在...

我不明白的是第一次运行时，为什么整个行绿色约翰和简，但是当我点击Vegetarian clickBox中的任何一个，只有comboBox单元格改变颜色而不是整行？

请记住，我真的对所有这些Java的东西都陌生，可能需要一个非常简单的解释。

非常感谢，

加里

下面的代码......（感谢） 包com.novartis.adhoc.view;

/* 
* TableRenderDemo.java requires no other files. 
*/ 

import javax.swing.DefaultCellEditor; 
import javax.swing.JComboBox; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.JTable; 
import javax.swing.table.AbstractTableModel; 
import javax.swing.table.DefaultTableCellRenderer; 
import javax.swing.table.TableCellRenderer; 
import javax.swing.table.TableColumn; 

import java.awt.Color; 
import java.awt.Component; 
import java.awt.Dimension; 
import java.awt.GridLayout; 

/** 
* TableRenderDemo is just like TableDemo, except that it explicitly initializes 
* column sizes and it uses a combo box as an editor for the Sport column. 
*/ 
public class TableRenderDemo extends JPanel { 

    private static final long serialVersionUID = 1L; 
    private boolean DEBUG = false; 

    public TableRenderDemo() { 
     super(new GridLayout(1, 0)); 

     JTable table = new JTable(new MyTableModel()) 
     { 
      private static final long serialVersionUID = 1L; 

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

       // Color row based on a cell value 
       if ((Boolean) getModel().getValueAt(modelRow, 4)) { 
        c.setBackground(Color.GREEN); 
       } else { 
        c.setBackground(getBackground()); 
       } 
       return c; 
      } 
     }; 

     table.setPreferredScrollableViewportSize(new Dimension(500, 70)); 
     table.setFillsViewportHeight(true); 

     // Create the scroll pane and add the table to it. 
     JScrollPane scrollPane = new JScrollPane(table); 

     // Set up column sizes. 
     initColumnSizes(table); 

     // Fiddle with the Sport column's cell editors/renderers. 
     setUpSportColumn(table, table.getColumnModel().getColumn(2)); 

     // Add the scroll pane to this panel. 
     add(scrollPane); 
    } 

    /* 
    * This method picks good column sizes. If all column heads are wider than 
    * the column's cells' contents, then you can just use 
    * column.sizeWidthToFit(). 
    */ 
    private void initColumnSizes(JTable table) { 
     MyTableModel model = (MyTableModel) table.getModel(); 
     TableColumn column = null; 
     Component comp = null; 
     int headerWidth = 0; 
     int cellWidth = 0; 
     Object[] longValues = model.longValues; 
     TableCellRenderer headerRenderer = table.getTableHeader().getDefaultRenderer(); 

     for (int i = 0; i < 5; i++) { 
      column = table.getColumnModel().getColumn(i); 

      comp = headerRenderer.getTableCellRendererComponent(null, 
        column.getHeaderValue(), false, false, 0, 0); 
      headerWidth = comp.getPreferredSize().width; 

      comp = table.getDefaultRenderer(model.getColumnClass(i)) 
        .getTableCellRendererComponent(table, longValues[i], false, false, 0, i); 
      cellWidth = comp.getPreferredSize().width; 

      if (DEBUG) { 
       System.out.println("Initializing width of column " + i + ". " 
         + "headerWidth = " + headerWidth + "; cellWidth = " 
         + cellWidth); 
      } 

      column.setPreferredWidth(Math.max(headerWidth, cellWidth)); 
     } 
    } 

    public void setUpSportColumn(JTable table, TableColumn sportColumn) { 
     // Set up the editor for the sport cells. 
     JComboBox<String> comboBox = new JComboBox<String>(); 
     comboBox.addItem("Snowboarding"); 
     comboBox.addItem("Rowing"); 
     comboBox.addItem("Knitting"); 
     comboBox.addItem("Speed reading"); 
     comboBox.addItem("Pool"); 
     comboBox.addItem("None of the above"); 
     sportColumn.setCellEditor(new DefaultCellEditor(comboBox)); 

     // Set up tool tips for the sport cells. 
     DefaultTableCellRenderer renderer = new DefaultTableCellRenderer(); 
     renderer.setToolTipText("Click for combo box"); 
     sportColumn.setCellRenderer(renderer); 
    } 

    class MyTableModel extends AbstractTableModel { 

     private static final long serialVersionUID = 1L; 
     private String[] columnNames = { "First Name", "Last Name", "Sport", 
       "# of Years", "Vegetarian" }; 
     private Object[][] data = { 
       { "Kathy", "Smith", "Snowboarding", new Integer(5), 
         new Boolean(false) }, 
       { "John", "Doe", "Rowing", new Integer(3), new Boolean(true) }, 
       { "Sue", "Black", "Knitting", new Integer(2), 
         new Boolean(false) }, 
       { "Jane", "White", "Speed reading", new Integer(20), 
         new Boolean(true) }, 
       { "Joe", "Brown", "Pool", new Integer(10), new Boolean(false) } }; 
     public final Object[] longValues = { "Jane", "Kathy", 
       "None of the above", new Integer(20), Boolean.TRUE }; 

     public int getColumnCount() { 
      return columnNames.length; 
     } 

     public int getRowCount() { 
      return data.length; 
     } 

     public String getColumnName(int col) { 
      return columnNames[col]; 
     } 

     public Object getValueAt(int row, int col) { 
      return data[row][col]; 
     } 

     /* 
     * JTable uses this method to determine the default renderer/ editor for 
     * each cell. If we didn't implement this method, then the last column 
     * would contain text ("true"/"false"), rather than a check box. 
     */ 
     public Class<? extends Object> getColumnClass(int c) { 
      return getValueAt(0, c).getClass(); 
     } 

     /* 
     * Don't need to implement this method unless your table's editable. 
     */ 
     public boolean isCellEditable(int row, int col) { 
      // Note that the data/cell address is constant, 
      // no matter where the cell appears onscreen. 
      if (col < 2) { 
       return false; 
      } 
      return true; 
     } 

     /* 
     * Don't need to implement this method unless your table's data can 
     * change. 
     */ 
     public void setValueAt(Object value, int row, int col) { 
      if (DEBUG) { 
       System.out.println("Setting value at " + row + "," + col 
         + " to " + value + " (an instance of " 
         + value.getClass() + ")"); 
      } 

      data[row][col] = value; 
      fireTableCellUpdated(row, col); 

      if (DEBUG) { 
       System.out.println("New value of data:"); 
       printDebugData(); 
      } 
     } 

     private void printDebugData() { 
      int numRows = getRowCount(); 
      int numCols = getColumnCount(); 

      for (int i = 0; i < numRows; i++) { 
       System.out.print(" row " + i + ":"); 
       for (int j = 0; j < numCols; j++) { 
        System.out.print(" " + data[i][j]); 
       } 
       System.out.println(); 
      } 
      System.out.println("--------------------------"); 
     } 

    } 

    /** 
    * Create the GUI and show it. For thread safety, this method should be 
    * invoked from the event-dispatching thread. 
    */ 
    private static void createAndShowGUI() { 
     // Create and set up the window. 
     JFrame frame = new JFrame("TableRenderDemo"); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

     // Create and set up the content pane. 
     TableRenderDemo newContentPane = new TableRenderDemo(); 
     newContentPane.setOpaque(true); // content panes must be opaque 
     frame.setContentPane(newContentPane); 

     // Display the window. 
     frame.pack(); 
     frame.setVisible(true); 
    } 

    public static void main(String[] args) { 
     // Schedule a job for the event-dispatching thread: 
     // creating and showing this application's GUI. 
     javax.swing.SwingUtilities.invokeLater(new Runnable() { 
      public void run() { 
       createAndShowGUI(); 
      } 
     }); 
    } 

} 

---

好了，我真的很想加入到岗位，而不是编辑原始的一个，但我不知道如何做到这一点（目前感觉真的很厚）。无论如何，我期待在此刻的以下部分...

TableCellRenderer headerRenderer = table.getTableHeader().getDefaultRenderer(); 

for (int i = 0; i < 5; i++) { 
    column = table.getColumnModel().getColumn(i); 

    comp = headerRenderer.getTableCellRendererComponent(
         null, column.getHeaderValue(), 
         false, false, 0, 0); 
    headerWidth = comp.getPreferredSize().width; 

    comp = table.getDefaultRenderer(model.getColumnClass(i)). 
        getTableCellRendererComponent(
         table, longValues[i], 
         false, false, 0, i); 
    cellWidth = comp.getPreferredSize().width; 
} 

所以我在此假设头有从表中的其余部分不同的渲染正确吗？

另外，我没有得到headerRenderer.getTableCellRendererComponent的参数... table = null，row = 0，column = 0。这是怎么回事？

而且，如果column.getHeaderValue（）返回对象在头列我，为什么我们不能只说：

comp = column.getHeaderValue(); 
headerWidth = comp.getPreferredSize().width; 

感谢，

加里

Answer 1

好，第一件事是代码是由一位同事提供给我的（我认为这是Oracle网站上的确切代码），但不是，他一直在玩它。

总之...

我不明白的是第一次运行时，为什么整个行绿色 约翰和简，但是当我点击素食clickBox对他们的任何 只comboBox单元格改变颜色而不是整行？

我想我已经想通了，为什么会这样 - 下面的代码是该行中的每个单元执行：

if ((Boolean) getModel().getValueAt(modelRow, 4)) { 
    c.setBackground(Color.GREEN); 
} else { 
    c.setBackground(getBackground()); 

所以，当表首先绘制...的第列，它检查列4中的值，如果它是'真'，它将列0中的单元格设置为绿色（和列1至3）。但是，当列4中的值更改为'假'时，呈现器未在列0（等）中的单元格上运行，因此它不知道再次执行此检查，因此颜色不能更改为其他列。

无论如何，我已经得到了解决此通过...

if ((Boolean) getModel().getValueAt(modelRow, 4)) { 
    c.setBackground(Color.GREEN); 
    repaint(); 
} else { 
    c.setBackground(getBackground()); 

四处逛逛！