桂互动

Question

这是我第一次创建Gui，我对如何创建交互感到困惑。

我正在尝试在组合框位于单个上时实现单一选择模式，而在组合框位于多个上时实现多个选择模式。我将它们放在多行注释中。

有什么想法吗？

  

//互动

     

///当选择“ Single”时，JList更改，因此仅一项   可以选择。

     

///当选择“多个”时，JList更改，因此可以   被选中

     

///当选择一个或多个国家时，JLabel   进行更改以反映新选择

public class GuiTest {


public static String[] Countries = {"Africa", "Haiti", "USA", "Poland", "Russia", "Canada", "Mexico", "Cuba"};
public static String[] Selection = {"Single", "Multiple"};

JPanel p = new JPanel();
JButton b = new JButton("Testing");
JComboBox jc = new JComboBox(Selection);

JList jl = new JList(Countries);


private static void constructGUI() {
    JFrame.setDefaultLookAndFeelDecorated(true);
    JFrame frame = new JFrame();
    frame.setTitle("Countries Selection");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    // add a JLabel that says Welcome
    JLabel label = new JLabel("Selected Items:");
    frame.add(label);
    frame.pack();



    JComboBox jc = new JComboBox(Selection);
    frame.add(jc);
    frame.pack();
    frame.setVisible(true);


    JList jl = new JList(Countries);
    frame.add(jl);
    frame.pack();



    JComponent panel = new JPanel();
    panel.setLayout(new FlowLayout());
    panel.add(new JLabel("Choose Selection Mode:"));
    panel.add(jc);
    frame.add(panel, BorderLayout.NORTH);
    frame.add(jl, BorderLayout.WEST);
    frame.add(label, BorderLayout.SOUTH);



}




public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            constructGUI();

        }
    });
}

}

Answer 1

您应该开始将模式添加到组合框：

comboBoxCategoria.addItem("Single",0);
comboBoxCategoria.addItem("Multiple",1);

然后将ActionListener添加到您的ComboBox中以修改列表选择模式

jc.addActionListener(new ActionListener() {
  public void actionPerformed(ActionEvent arg0) {
    if(jc.getSelectedItem().equals("Single")){
      jl.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    }else{//must equals
      jl.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
    }
  }
});

最后在列表上添加一个MouseListener，以检测列表选择的更改，并更改JLabel以反映新的选择

jl.addMouseListener(new MouseAdapter() {
  @Override
  public void mouseReleased(MouseEvent e) { 
    label.setText(list.getSelectedValuesList().toString());
  }
});

编辑：您还应该添加KeyListener来更新标签，因为可以通过箭头键更改选择

jl.addKeyListener(new KeyAdapter() {
  @Override
  public void keyReleased(KeyEvent e) {
    label.setText(list.getSelectedValuesList().toString());
  }
});

Answer 2

会是这样的：

    jc.addActionListener((evt) -> {
        if ("Single".equals(jc.getSelectedItem())) {
            jl.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
            int[] sel = jl.getSelectedIndices();
            if (sel != null && sel.length > 1) {
                jl.setSelectedIndex(sel[0]);
            }
        } else {
            jl.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
        }
    });
    jl.addListSelectionListener((evt) -> {
        StringBuilder buf = new StringBuilder();
        for (Object o: jl.getSelectedValuesList()) {
            if (buf.length() > 0) {
                buf.append(", ");
            }
            buf.append(o);
        }
        label.setText(buf.toString());
    });
    jc.setSelectedItem("Single");