如何设置JCheckBox以使用JScrollPane？

Question

I want to make JCheckBox List to use arraylist into this left side JScrollPane. But This JScrollPane just paste and add the last index JCheckBox. Any moment just don't make me solve this problem. Do I add JList? I want to solve this as quickly as I can. Here is my Code.

package dimi.voca;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import java.util.ArrayList;
import javax.swing.JCheckBox;
import javax.swing.ScrollPaneConstants;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.ScrollPane;
import java.awt.event.ActionEvent;
import javax.swing.JTextArea;
import javax.swing.Box;
import javax.swing.JList;

public class LearnSelect extends JFrame
{
    public LearnSelect() {
        super("DimiVoca in PC");

        JPanel panel = new JPanel();
        setSize(650, 500);

        getContentPane().setLayout(null);

        JScrollPane scrollPane = new JScrollPane();

        JList list = new JList();
        panel.add(list);

        scrollPane.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
        scrollPane.setToolTipText("");
        scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
        scrollPane.setBounds(28, 10, 200, 441);
        getContentPane().add(scrollPane);

        ArrayList<JCheckBox> Day = new ArrayList<JCheckBox>();
        String label[] = {  "Day 1", "Day 2", "Day 3", "Day 4", "Day 5", "Day 6",
                            "Day 7", "Day 8", "Day 9", "Day 10", "Day 11", "Day 12",
                            "Day 13", "Day 14", "Day 15", "Day 16", "Day 17", "Day 18", 
                            "Day 19", "Day 20", "Day 21", "Day 22", "Day 23", "Day 24", 
                            "Day 25", "Day 26", "Day 27", "Day 28", "Day 29", "Day 30", 
                            "Day 31", "Day 32", "Day 33", "Day 34", "Day 35", "Day 36", 
                            "Day 37", "Day 38", "Day 39", "Day 40", "Day 41", "Day 42", 
                            "Day 43", "Day 44", "Day 45", "Day 46", "Day 47", "Day 48", 
                            "Day 49", "Day 50", "Day 51", "Day 52", "Day 53", "Day 54", 
                            "Day 55", "Day 56", "Day 57", "Day 58", "Day 59", "Day 60"};
        for(int i = 0; i <= label.length - 1; i++)
        {
            JCheckBox checkbox = new JCheckBox(label[i]);
            Day.add(checkbox);
            scrollPane.setViewportView(checkbox);
        }

        JScrollPane scrollPane_1 = new JScrollPane();
        scrollPane_1.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER);
        scrollPane_1.setToolTipText("");
        scrollPane_1.setBounds(227, 10, 200, 441);
        getContentPane().add(scrollPane_1);

        JButton close = new JButton("\uB2EB\uAE30");
        close.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) 
            {
                dispose();
            }
        });
        close.setBounds(481, 428, 97, 23);
        getContentPane().add(close);

        JButton start = new JButton("\uC2DC\uC791");
        start.setBounds(481, 395, 97, 23);
        getContentPane().add(start);

        JCheckBox isRandom = new JCheckBox("\uB79C\uB364 \uD5C8\uC6A9");
        isRandom.setBounds(481, 100, 145, 23);
        getContentPane().add(isRandom);

        JCheckBox loadCreate = new JCheckBox("Create\uC5D0\uC11C \uBC1B\uC544\uC624\uAE30");
        loadCreate.setBounds(481, 150, 145, 23);
        getContentPane().add(loadCreate);

        setVisible(true);
    }
}

Answer 1

In your for loop, you're setting your scrollpane's viewport view to the last JCheckBox, and it will be the only one seen. If you want all the JCheckBoxes seen within the scrollpane, then create a JPanel before the for loop, give it a GridLayout, and add your JCheckBoxes to this single JPanel inside the for loop. Then add that JPanel to the JScrollPane's viewport view.

JPanel dayPanel = new JPanel(new GridLayout(0, 1)); // !!

ArrayList<JCheckBox> Day = new ArrayList<JCheckBox>();
String label[] = { "Day 1", "Day 2", "Day 3", "Day 4", "Day 5", "Day 6", "Day 7", "Day 8",
        "Day 9", "Day 10", "Day 11", "Day 12", "Day 13", "Day 14", "Day 15", "Day 16",
        "Day 17", "Day 18", "Day 19", "Day 20", "Day 21", "Day 22", "Day 23", "Day 24",
        "Day 25", "Day 26", "Day 27", "Day 28", "Day 29", "Day 30", "Day 31", "Day 32",
        "Day 33", "Day 34", "Day 35", "Day 36", "Day 37", "Day 38", "Day 39", "Day 40",
        "Day 41", "Day 42", "Day 43", "Day 44", "Day 45", "Day 46", "Day 47", "Day 48",
        "Day 49", "Day 50", "Day 51", "Day 52", "Day 53", "Day 54", "Day 55", "Day 56",
        "Day 57", "Day 58", "Day 59", "Day 60" };
for (int i = 0; i <= label.length - 1; i++) {
    JCheckBox checkbox = new JCheckBox(label[i]);
    Day.add(checkbox);
    // !! scrollPane.setViewportView(checkbox);
    dayPanel.add(checkbox);  // !!
}

scrollPane.setViewportView(dayPanel);  // !!

Another problem is here:

getContentPane().setLayout(null);

While null layouts and setBounds() might seem to Swing newbies like the easiest and best way to create complex GUI's, the more Swing GUI'S you create the more serious difficulties you will run into when using them. They won't resize your components when the GUI resizes, they are a pain to enhance or maintain, they fail completely when placed in scrollpanes, they look gawd-awful when viewed on all platforms or screen resolutions that are different from the original one.

You will want to learn about the layout managers and use them.