JList停止選擇最后一個項目

Question

我在選擇JList時遇到問題。 當我單擊JList中的任何對象時，它將被選中（很好）。

但是，當我單擊所有對象的下方（在空白處）時，將選擇JList中的最后一項。 如何關閉它？ 在所有對象（在空白區域）下面單擊之后，我不想在JList中選擇最后一個對象。

經過幾句評論后，我將在此處添加代碼示例。

import java.awt.Color;
import java.awt.Dimension;

import javax.swing.DefaultListModel;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.ListSelectionModel;
import javax.swing.UIManager;
import javax.swing.UIManager.LookAndFeelInfo;

public class TestOfJList extends JFrame{

private static JList playList;
private static DefaultListModel<String> modelPlayList;  
private static JPanel mainPanel;
private static MyCellRenderer myRendererForJlist;

private static void createAndShowGUI() {

    JFrame.setDefaultLookAndFeelDecorated(true);
    try {       
        for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    }catch (Exception e){
      e.printStackTrace();
    }

    JFrame frame = new JFrame("JListTest!");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(700, 250, 300, 400);       
    frame.setResizable(false);    

    mainPanel = new JPanel();

    modelPlayList = new DefaultListModel<String>();

    modelPlayList.addElement("Hello world!");
    modelPlayList.addElement("Hello heaven!");
    modelPlayList.addElement("Hello hell!");


    playList = new JList(modelPlayList);

    playList.setPreferredSize(new Dimension(270,500));
    playList.setVisible(true);
    playList.setBackground(Color.LIGHT_GRAY);       
    playList.setSelectionBackground(Color.YELLOW);      
    playList.setSelectedIndex(0);
    playList.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
    playList.setDragEnabled(true);      
    playList.setDropMode(javax.swing.DropMode.ON_OR_INSERT);
    playList.setFixedCellHeight(20);        

    JScrollPane scrollPane = new JScrollPane(playList);
    scrollPane.setPreferredSize(new Dimension(300,400));

    mainPanel.add(scrollPane);

    myRendererForJlist = new MyCellRenderer();      
    playList.setCellRenderer(myRendererForJlist);

    frame.add(mainPanel);       
    frame.setVisible(true);     
}

public static void main(String[] args) {

    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            createAndShowGUI();
        }
    });
}
}

---

MCVE 2：

import java.awt.event.MouseListener;
import javax.swing.*;

public class TestList {
   public static final String[] ITEMS = { "One", "Two", "Three", "Four", "Five" };

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            JList<String> myList = new JList<>(ITEMS);
            myList.setVisibleRowCount(10);
            JScrollPane sPane = new JScrollPane(myList);

            // just to see what listeners are involved
            MouseListener[] mouseListeners = myList.getListeners(MouseListener.class);
            System.out.println(mouseListeners.length);

            MouseMotionListener[] mouseMotionListeners = myList.getListeners(MouseMotionListener.class);
            System.out.println(mouseMotionListeners.length);


            JOptionPane.showMessageDialog(null, sPane);
         }
      });
   }
}

Answer 1

您需要更改滾動面板的首選大小，因為它會擴展整個主面板，並且當您單擊最后一個元素（在空白區域）下方時，它會被選中

變更：-

scrollPane.setPreferredSize(new Dimension(300,400));

至

scrollPane.setPreferredSize(new Dimension(300,100));

現在單擊下面的列表將不會更改選擇。

如下所示