java - 行选择后 JTable 更新

Question

这是一个 JTextField 的 SSCCE，它自动完成 JTable。

它工作得很好，直到我想在选择一行时执行某些操作。问题是，每当选择 JTable 中的一行时，更改 JTextField 文本都会引发异常:

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: -1
    at java.util.Vector.elementAt(Vector.java:430)
    at javax.swing.table.DefaultTableModel.getValueAt(DefaultTableModel.java:632)
    at javax.swing.JTable.getValueAt(JTable.java:2681)
    at fr.ensicaen.si.client.AnimalAutoComplete$1.valueChanged(AnimalAutoComplete.java:73)
    at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:167)
    at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:147)
    at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:194)
    at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:388)
    at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:398)
    at javax.swing.DefaultListSelectionModel.removeSelectionIntervalImpl(DefaultListSelectionModel.java:559)
    at javax.swing.DefaultListSelectionModel.clearSelection(DefaultListSelectionModel.java:403)
    at javax.swing.JTable.clearSelection(JTable.java:2075)
    at fr.ensicaen.si.client.AnimalAutoComplete$AutoCompleteListener.fill(AnimalAutoComplete.java:97)
    at fr.ensicaen.si.client.AnimalAutoComplete$AutoCompleteListener.insertUpdate(AnimalAutoComplete.java:93)

事实上，选择一行并执行某些操作是有效的。但是，当修改 JTextField 时，ListSelectionListener 再次被触发(但不应该？)，我不明白为什么!

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.util.ArrayList;
import java.util.List;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
import javax.swing.table.DefaultTableModel;

import java.awt.GridLayout;

public class AnimalAutoComplete extends JFrame {

    private JPanel contentPane;
    private JScrollPane animalPane;
    private JTable animalTable;
    private JPanel panel;
    private JTextField animalField;

    /** Create the frame. */
    public AnimalAutoComplete() {
        /* Frame structure */
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 710, 471);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new BorderLayout(0, 0));
        setContentPane(contentPane);
        animalPane = new JScrollPane();
        contentPane.add(animalPane, BorderLayout.CENTER);
        panel = new JPanel();
        contentPane.add(panel, BorderLayout.NORTH);
        panel.setLayout(new GridLayout(1, 0, 0, 0));

        /* JTable model */
        DefaultTableModel animalModel = new DefaultTableModel();
        animalTable = new JTable(animalModel);
        animalPane.setViewportView(animalTable);
        animalModel.addColumn("Animal"); 

        /* Initially fills the JTable */
        List<String> animals = new ArrayList<String>();
        animals.add("Dog");
        animals.add("Cat");
        animals.add("Fish");

        for (String a : animals) {
            animalModel.addRow( new Object[] {a} );
        }

        /* Text fields */
        animalField = new JTextField();
        panel.add(animalField);
        animalField.setColumns(10);

        /* This listener updates the JTable depending on the JTextField */
        animalField.getDocument().addDocumentListener(new AutoCompleteListener(animalTable, animals, animalField));

        /* This listener will do something useful when an animal is selected*/
        animalTable.getSelectionModel().addListSelectionListener(
            new ListSelectionListener(){
                public void valueChanged(ListSelectionEvent event) {
                    System.out.println(animalTable.getValueAt(animalTable.getSelectedRow(), 0));
                }
            }
        );

    }

    private final class AutoCompleteListener implements DocumentListener {
        private final JTable animalTable;
        private final List<String> animals;
        private JTextField searchedAnimal;

        private AutoCompleteListener(JTable animalTable,
                List<String> animals, JTextField textAnimal) {
            this.animalTable= animalTable;
            this.animals = animals;
            this.searchedAnimal = textAnimal;
        }

        public void changedUpdate(DocumentEvent arg0) {fill();}
        public void insertUpdate(DocumentEvent arg0) {fill();}
        public void removeUpdate(DocumentEvent arg0) {fill();}

        public void fill() {
            animalTable.clearSelection();
            DefaultTableModel model = (DefaultTableModel) animalTable.getModel();
            model.setRowCount(0);
            for (String a : animals) {
                if (a.startsWith(this.searchedAnimal.getText())) {
                    model.addRow(new Object[] {a});
                }
            }
        }
    }

    public static void main(String[] args) {
        AnimalAutoComplete frame = new AnimalAutoComplete();
        frame.setVisible(true);
    }
}

Answer 1

问题是当选择表格行(或列/单元格)时，选择事件会被触发两次。第一次使用索引 -1，第二次使用正确的索引。因此，请检查 animalTable.getSelectedRow() 是否返回 -1 的条件:

        public void valueChanged(ListSelectionEvent event) {
             int selRow = animalTable.getSelectedRow()
             if(selRow >= 0)
             {
                System.out.println(animalTable.getValueAt(selRow, 0));
                // or do other things
             }
         }

正如 @camickr 在下面所建议的，您还可以使用 event.getValueIsAdjusting()方法:如果选择仍在更改，则返回 true。许多列表选择监听器只对选择的最终状态感兴趣，并且当此方法返回 true 时可以忽略列表选择事件。事实上，使用此函数比上面提到的函数更可取，因为它使操作代码更加具体。