java JButton在JTable中选择行时不重新启用

Question

我试图在创建按钮时将其设置为enabled（假），当我选择Jtable上的任何一行时，该按钮变为enabled（真）

这里的逻辑非常简单，但由于某种原因，它不太起作用，按钮永远不会进入启用状态（true）

    JButton btnIniciarReparacin = new JButton("INICIAR REPARACI\u00D3N");
    
    btnIniciarReparacin.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            tiempoStart = (int) (System.currentTimeMillis() / 1000L);
            btnIniciarReparacin.setEnabled(false);
        }
    });
    btnIniciarReparacin.setFont(new Font("SansSerif", Font.BOLD, 13));
    btnIniciarReparacin.setBackground(new Color(231, 111, 81));
    btnIniciarReparacin.setBounds(129, 625, 254, 50);
    frame.getContentPane().add(btnIniciarReparacin);
    
    int row = table.getSelectedRow();
    //Comprobamos si hemos cogido algo de la tabla y si los botones están encendidos
    if (table.isRowSelected(row)) {
        btnIniciarReparacin.setEnabled(true);
    } else {
        btnIniciarReparacin.setEnabled(false);
    }

Answer 1

Swing GUI的工作是向事件添加侦听器，然后响应侦听器中的状态更改

在创建组件的代码中，您似乎正在检查行选择状态，这永远不会起作用，因为它只检查一次状态，而且在用户有机会进行选择之前。相反，您需要在JTable上使用一个侦听器，更具体地说，是一个ListSelectionListener，您可以通过table.getSelectionModel().addListSelectionListener(...)将它添加到JTable的选择模型中

还请注意：

int row = table.getSelectedRow();
if (table.isRowSelected(row)) {
    btnIniciarReparacin.setEnabled(true);
} else {
    btnIniciarReparacin.setEnabled(false);
}

可以缩短为：

int row = table.getSelectedRow();
btnIniciarReparacin.setEnabled(table.isRowSelected(row));

例如：

table.getSelectionModel().addListSelectionListener(new ListSelectionListener(){
    public void valueChanged(ListSelectionEvent event) {
        int row = table.getSelectedRow();
        btnIniciarReparacin.setEnabled(table.isRowSelected(row));
    }
});

例如，如果按钮删除一行：

import java.awt.BorderLayout;
import javax.swing.*;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
import javax.swing.table.DefaultTableModel;

@SuppressWarnings("serial")
public class Test01 extends JPanel {
    private static final String[] COLUMNS = {"One", "Two", "Three", "Four"};
    private DefaultTableModel tableModel = new DefaultTableModel(COLUMNS, 0);
    private JTable table = new JTable(tableModel);
    private JButton deleteRowButton = new JButton("Delete Row");
    
    public Test01() {
        int tableRows = 20;
        for (int i = 0; i < tableRows; i++) {
            Integer[] row = new Integer[COLUMNS.length];
            for (int j = 0; j < row.length; j++) {
                row[j] = (int) (100 * Math.random());
            }
            tableModel.addRow(row);
        }
        
        table.getSelectionModel().setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        table.getSelectionModel().addListSelectionListener(new ListSelectionListener() {
            
            @Override
            public void valueChanged(ListSelectionEvent e) {
                int row = table.getSelectedRow();
                deleteRowButton.setEnabled(table.isRowSelected(row));
            }
        });
        
        deleteRowButton.addActionListener(e -> {
            int row = table.getSelectedRow();
            tableModel.removeRow(row);
        });
        deleteRowButton.setEnabled(false);
        JPanel bottomPanel = new JPanel();
        bottomPanel.add(deleteRowButton);
        
        setLayout(new BorderLayout());
        add(new JScrollPane(table));
        add(bottomPanel, BorderLayout.PAGE_END);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }

    private static void createAndShowGui() {
        Test01 mainPanel = new Test01();
        JFrame frame = new JFrame("Test01");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.add(mainPanel);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }
}