java，JList位置

Question

我被卡在这里了，但我不能把布局中的列表移到左上角。我正试图用list.setLocation();将列表移到左上角，但这似乎不管用。谢谢大家!

public class JList_ extends JFrame {
    private JList list;
    private static String[] colorname = {"black", "blue", "red", "white"};
    private static Color[] colors = {Color.BLACK, Color.BLUE, Color.RED,
            Color.WHITE};

    public JList_() {
        super("titile");
        setLayout(new FlowLayout());

        list = new JList(colorname);
        list.setVisibleRowCount(10);
        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        list.setLocation();

        add(new JScrollPane(list));


        list.addListSelectionListener(
                new ListSelectionListener() {
                    public void valueChanged(ListSelectionEvent event) {

                        getContentPane().setBackground(colors[list.getSelectedIndex()]);

                    }

                }

        );
    }
}    

Answer 1

您可以对JFrame使用setLayout（null）。然后可以使用setBounds（）方法根据需要在JFrame上的任何位置设置列表位置

Answer 2

setLocation()函数将两个整数作为参数。trylist.setLocation(0,0)另一个重载函数将Point对象作为参数。它将零部件放置在父对象的指定位置

另外，您正在将JList放置在JScrollPane中并将其添加到帧中。因此，请尝试为JScrollPane创建一个单独的对象，然后将其位置设置为0,0

JScrollPane myScrollPane = new JScrollPane(list);
add(myScrollPane);
myScrollPane.setLocation(0,0);

上面的代码片段应该适合您

Answer 3

只需将布局中的路线设置为左侧

 layout.setAlignment(FlowLayout.LEFT);

使用您的代码的完整工作示例：

import java.awt.Color;
import java.awt.FlowLayout;

import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.ListSelectionModel;
import javax.swing.SwingUtilities;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

public class ListLocation extends JFrame {

    private JList<String> list;
    private static String[] colorname = {"black", "blue", "red", "white"};
    private static Color[] colors = {Color.BLACK, Color.BLUE, Color.RED, Color.WHITE};

    public ListLocation() {
        super("title");

        FlowLayout layout = new FlowLayout();
        layout.setAlignment(FlowLayout.LEFT);

        list = new JList<String>(colorname);
        list.setVisibleRowCount(10);
        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);

        setLayout(layout);
        add(list);

        list.addListSelectionListener(
                new ListSelectionListener() {

            @Override
            public void valueChanged(ListSelectionEvent e) {
                getContentPane().setBackground(colors[list.getSelectedIndex()]);
            }
        }
        );

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(800, 800);
        setLocationRelativeTo(null);

        setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                try {
                    new ListLocation();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

有关How to Use FlowLayout中FlowLayout的详细信息