Question

我正在尝试从comboBox在JPanel中添加一些按钮。 comboBox有一个8个整数的数组，当其中一个被选中时，我希望能够按下一个go按钮，然后按钮将显示从组合框中选择的按钮数到JPanel中。

JPanel最初为空，并且在选择某些内容之前禁用了go按钮。

我已经创建了JPanel，comboBox和go按钮，但我现在已经迷失了如何获取和创建按钮。

组合框填充了字符串 -

String[] floorStrings = {"Select one", "1", "2", "3", "4", "5", "6", "7", "8"};
//Create the combo box
JComboBox floorList = new JComboBox(floorStrings);

actionPerformed代码 -

        public void actionPerformed(ActionEvent e) {

        floorList.getSelectedIndex();
        //int i = Integer.valueOf((String) floorList);

    if (e.getSource() == go) {
        go.setText("Stop");
        System.out.print("Clicked " + floorList);
        p3.add(go, BorderLayout.NORTH);
    } 

}

Answer 1

将ActionListener附加到“开始”按钮。在actionPerformed方法中，您需要从JComboBox获取值，只需使用getSelectedValue。这将返回Object。检查对象是否为null并尝试将其转换为int（即(int)value）。

如果演员表已成功，只需创建一个for-next循环，根据组合框中的值循环n次，然后创建按钮，将它们添加到面板中。

查看How to Write an Action Listener和How to use Combo Boxes以及The for Statement了解详情

使用示例更新

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.management.StringValueExp;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestComboBox08 {

    public static void main(String[] args) {
        new TestComboBox08();
    }

    public TestComboBox08() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private JComboBox floorList;
        private JPanel buttons;

        public TestPane() {
            setLayout(new BorderLayout());
            String[] floorStrings = {"Select one", "1", "2", "3", "4", "5", "6", "7", "8"};
            floorList = new JComboBox(floorStrings);
            JButton go = new JButton("Go");
            go.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    int count = floorList.getSelectedIndex();
                    buttons.removeAll();
                    for (int index = 0; index < count; index++) {
                        buttons.add(new JButton(String.valueOf(index)));
                    }
                    buttons.revalidate();
                }
            });
            JPanel top = new JPanel(new FlowLayout(FlowLayout.CENTER));
            top.add(floorList);
            top.add(go);

            buttons = new JPanel(new GridLayout(0, 4));
            buttons.setPreferredSize(new Dimension(200, 200));

            add(top, BorderLayout.NORTH);
            add(buttons);
        }
    }
}

如何从comboBox中的数字列表向JPanel添加按钮

1 个答案: