Java 如何将JTable中的JComboBox重置为JComboBox的第一个值

我正在用JavaSwing编写代码。我已经在JTable中创建了一个JComboBox。它正在工作：）。但一旦我选择了一个值并单击save或cancel按钮，它就必须重置为默认值（组合框中的第一个值）。我尝试了很多方法，比如

combobox.setSelectedIndex（0）

。这不管用。 代码：

• 包含有关的说明

• 所有数据都存储在

• JTable视图中的所有更改如中所述

• 然后，您必须知道，在XxxTableModel中，仅存储以下对象的字符串值（或

  Double

  或

  Long

  或

  Integer

  或

  图标

  ，取决于ComboBoxModel中存储的值）

• 结果是

基于教程代码的快速代码（对不起，我太懒了）

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();
            }
        });
    }
}

---

在TableCellEditor上调用setValue时，可以设置组合框的选定值

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();
            }
        });
    }
}

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)