如何將JTable中的JComboBox重置爲JComboBox的第一個值

Question

我正在研究Java Swing中的代碼。我在JTable中創建了一個JComboBox。它的工作:)。但是，一旦我選擇一個值並單擊保存或取消按鈕，它必須重置爲默認值（組合框中的第一個值）。我嘗試了很多方法，如combobox.setSelectedIndex(0)。這不起作用。 代碼：

String[] manTimeHr = { "00","01", "02", "03","04","05","06","07","08","09","10","11","12","13","14","15","16","17","18","19","20","21","22","23"}; 
     String[] manTimeMin = {"00","01", "02", "03","04","05","06","07","08","09","10","11","12","13", "14", "15","16","17","18","19","20","21","22","23","24","25", "26", "27","28","29","30","31","32","33","34","35","36","37","38","39","40","41","42","43","44","45","46","47","48","49","50","51","52","53","54","55","56","57","58","59"}; 
     String[][] data = {{"-select-","-select-"}}; 
     String[] cols = {"Hrs","Mins"}; 
     String[][] data1 = {{"-select-","-select-"}}; 
     String[] cols1 = {"Hrs","Mins"}; 
     JLabel manTimeStart = new JLabel("Start From",JLabel.LEFT); 
     STimeTbl = new JTable(data,cols); 
     hrsColumn=STimeTbl.getColumnModel().getColumn(0); 
     minsColumn=STimeTbl.getColumnModel().getColumn(1); 
     manSiteStimeHrCBx = new JComboBox(manTimeHr); 
     manSiteStimeHrCBx.setSelectedIndex(0); 
     hrsColumn.setCellEditor(new DefaultCellEditor(manSiteStimeHrCBx)); 
     manSiteStimeMinCBx = new JComboBox(manTimeMin); 
     manSiteStimeMinCBx.setSelectedIndex(0); 
     minsColumn.setCellEditor(new DefaultCellEditor(manSiteStimeMinCBx)); 
     JLabel manTimeEnd = new JLabel("End To",JLabel.LEFT); 
     ETimeTbl = new JTable(data1,cols1); 
     hrsColumn1=ETimeTbl.getColumnModel().getColumn(0); 
     minsColumn1=ETimeTbl.getColumnModel().getColumn(1); 
     manSiteEtimeHrCBx = new JComboBox(manTimeHr); 
     manSiteEtimeHrCBx.setSelectedIndex(0); 
     hrsColumn1.setCellEditor(new DefaultCellEditor(manSiteEtimeHrCBx)); 
     manSiteEtimeMinCBx = new JComboBox(manTimeMin); 
     manSiteEtimeMinCBx.setSelectedIndex(0); 
     minsColumn1.setCellEditor(new DefaultCellEditor(manSiteEtimeMinCBx)); 
     . 
     . 
     . 
     . 
     if("Save".equals(e.getActionCommand())) { 
     try{ 
        mSHr = Integer.parseInt((String)manSiteStimeHrCBx.getSelectedItem()); 
        mEHr=Integer.parseInt((String)manSiteEtimeHrCBx.getSelectedItem()); 
        mSMin=Integer.parseInt((String)manSiteStimeMinCBx.getSelectedItem()); 
        mEMin=Integer.parseInt((String)manServEtimeMinCBx.getSelectedItem()); 
       }catch (Exception en){ 
       System.out.println("Main Exception : "+ en); 
        return; 
       } 
       if(validateBlockTime(mSHr,mEHr,mSMin,mEMin) != true) 
       { 
        System.out.println("Enter valid Time"); 
        return; 
       } 
       manSiteStimeHrCBx.setSelectedIndex(0); 
       manSiteStimeMinCBx.setSelectedIndex(0); 
       manSiteEtimeHrCBx.setSelectedIndex(0); 
       manSiteEtimeMinCBx.setSelectedIndex(0); 
     . 
     . 
     . 
     private static boolean validateBlockTime(int val3, int val4, int val5, int val6){ 
     if(val4 > val3) 
      return true; 
     else if((val4 == val3) && (val6 > val5)) 
      return true; 
     else 
      return false; 
     } 

Answer 1

• JTable tutorial含有描述有關Combo Box as an Editor

• 所有數據都存儲在XxxTableModel

• 在JTable視圖中的所有的變化Concepts: Editors and Renderers

• 描述那麼你必須知道在XxxTableModel只存儲字符串值（或Double或Long或Integer或Icon，取決於存儲在ComboBoxModel中值）Combo Box as an Editor

• 結果是

快代碼（對不起，我很懶）根據教程代碼

import java.awt.BorderLayout; 
import java.awt.event.ActionEvent; 
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.Component; 
import java.awt.Dimension; 
import java.awt.event.ActionListener; 
import javax.swing.JButton; 

public class TableRenderDemo extends JPanel { 

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

    public TableRenderDemo() { 
     super(new BorderLayout(5, 5)); 
     final JTable table = new JTable(new MyTableModel()); 
     table.setRowHeight(18); 
     table.setPreferredScrollableViewportSize(new Dimension(500, 70)); 
     table.setFillsViewportHeight(true); 
     table.setPreferredScrollableViewportSize(table.getPreferredSize()); 
     JScrollPane scrollPane = new JScrollPane(table); 
     initColumnSizes(table); 
     setUpSportColumn(table, table.getColumnModel().getColumn(2)); 
     add(scrollPane); 
     JButton resetButton = new JButton("Reset to default"); 
     resetButton.addActionListener(new ActionListener() { 

      public void actionPerformed(ActionEvent e) { 
       for (int i = 0; i < table.getRowCount(); i++) { 
        table.getModel().setValueAt("None of the above", i, 2); 
       } 
      } 
     }); 
     add(resetButton, BorderLayout.SOUTH); 
    } 

    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)); 
     } 
    } 

    private void setUpSportColumn(JTable table, TableColumn sportColumn) { 
     JComboBox comboBox = new JComboBox(); 
     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)); 
     DefaultTableCellRenderer renderer = new DefaultTableCellRenderer(); 
     renderer.setToolTipText("Click for combo box"); 
     sportColumn.setCellRenderer(renderer); 
    } 

    private 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), false}, 
      {"John", "Doe", "Rowing", new Integer(3), true}, 
      {"Sue", "Black", "Knitting", new Integer(2), false}, 
      {"Jane", "White", "Speed reading", new Integer(20), true}, 
      {"Joe", "Brown", "Pool", new Integer(10), 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; 
     } 

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

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

     @Override 
     public Class<?> getColumnClass(int c) { 
      return getValueAt(0, c).getClass(); 
     } 

     @Override 
     public boolean isCellEditable(int row, int col) { 
      if (col < 2) { 
       return false; 
      } else { 
       return true; 
      } 
     } 

     @Override 
     public void setValueAt(Object value, int row, int col) { 
      data[row][col] = value; 
      fireTableCellUpdated(row, col); 
      System.out.println(getValueAt(row, col)); 
     } 
    } 

    private static void createAndShowGUI() { 
     JFrame frame = new JFrame("TableRenderDemo"); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     TableRenderDemo newContentPane = new TableRenderDemo(); 
     newContentPane.setOpaque(true); //content panes must be opaque 
     frame.setContentPane(newContentPane); 
     frame.pack(); 
     frame.setVisible(true); 
    } 

    public static void main(String[] args) { 
     javax.swing.SwingUtilities.invokeLater(new Runnable() { 

      public void run() { 
       createAndShowGUI(); 
      } 
     }); 
    } 
} 

從

輸出，代碼行135th.

run: 
None of the above 
None of the above 
None of the above 
None of the above 
None of the above 
BUILD SUCCESSFUL (total time: 37 seconds)