将Jlist添加到JScrollPane

Question

我有一个JList,我需要放在滚动窗格内,因为我从数据库中获取JList,值可以大大增加.我需要能够将它们向下滚动,所以我写道:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;

import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.ListSelectionModel;
public class Checkboxlistener extends JFrame {

private JPanel jpAcc = new JPanel();
private JList checkBoxesJList;

Checkboxlistener() {
   // super("Deposit base", false, true, false, true);
    setSize(1300, 600);
    jpAcc.setLayout(null);
    jpAcc.setBackground(Color.LIGHT_GRAY);
    String labels[] = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J"};
    checkBoxesJList = new JList(labels);

    checkBoxesJList.setBounds(10, 30, 80, 600);
    checkBoxesJList.setBackground(Color.LIGHT_GRAY);
    checkBoxesJList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    JScrollPane scrollPane = new JScrollPane(checkBoxesJList);

    jpAcc.add(checkBoxesJList);
    jpAcc.add(scrollPane);



    getContentPane().add(jpAcc);
    setVisible(true);
}

public static void main(String args[]) {
   Checkboxlistener cbl = new Checkboxlistener();
}
}

我做错了什么因为我看不到任何ScrollPane？

Answer 1

该列表已包含在滚动窗格内,因此您不能将列表添加到主面板.只有滚动窗格.

你做错的另一件事是不使用布局管理器,并设置组件的边界和大小.不要那样做.让布局管理器为您定位和调整组件的大小.

最后,您不应该使用主线程中的Swing组件.仅在事件派发线程中.

这是您的代码的修改版本,工作正常.我删除了背景颜色,因为这应该由L&F处理:

public class Checkboxlistener extends JFrame {

    private JPanel jpAcc = new JPanel();
    private JList<String> checkBoxesJList;

    Checkboxlistener() {
        jpAcc.setLayout(new BorderLayout());
        String labels[] = { "A", "B", "C", "D", "E", "F", "G", "H", "I", "J" };
        checkBoxesJList = new JList<String>(labels);

        checkBoxesJList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        JScrollPane scrollPane = new JScrollPane(checkBoxesJList);

        jpAcc.add(scrollPane);

        getContentPane().add(jpAcc);
        pack();
    }

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

            @Override
            public void run() {
                Checkboxlistener cbl = new Checkboxlistener();
                cbl.setVisible(true);
            }
        });
    }
}