如何在 JList 中按属性搜索项目

Question

I have an item class and I store items in a JList, I would like to look for an item in a JList by the name of the item. I have a JButton called search that implements the next code, and nameToSearch variable gets the string written in a JTextfield,

  ArrayList<Item> backUp = new ArrayList<>();
            ArrayList<Item> itemsFound = new ArrayList<>();

            for (int i = 0; i < listModel.getSize(); i++) {
                backUp.add(listModel.getElementAt(i));

                if (listModel.getElementAt(i).getName().compareToIgnoreCase(nameToSearch) >= 0) {
                    Item foundItem = listModel.getElementAt(i);
                    itemsFound.add(foundItem);
                }
            }
                //clear the listModel to display the found items
                listModel.removeAllElements();
                //add the found items to the listModel to be displayed
                for (Item s: itemsFound) {
                    listModel.addElement(s);}

I meant to get all the items in a backup arrayList to show all of the items later, the if statement checks is the item.getName() is is what the user is looking for and it adds that element to a itemfound ArrayList, it is supposed to have the item found in the arrayList, then i remove all the elements from the defaultListModel listmodel and then add the found items in the defaultListModel listModel so the found items are the only ones on the JList for that moment. But this doesnt work,it doesnt do anything. any suggestion on how to do it is well appreciated

Answer 1

A very simple solution can be to:

1. Store all items into a collection of your preference, or array.
2. Use a DefaultListModel (which is programmatically dynamic) for the JList .
3. For each search operation clear the model and then add one after another the items which match the search criteria.

For example:

import java.awt.BorderLayout;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;

public class Main {

    //Assuming the class Item is similar to the following implementation:
    public static class Item {
        private final String name;

        public Item(final String name) {
            this.name = Objects.requireNonNull(name);
        }

        public String getName() {
            return name;
        }

        //Overriding toString method, to avoid implementing a custom ListCellRenderer...
        @Override
        public String toString() {
            return getName();
        }
    }

    public static void main(final String[] args) {

        //The following list contains all the initial Items lets say:
        final List<Item> allItems = Arrays.asList(new Item("abc"), new Item("ABC"),
                                                  new Item("def"), new Item("DEF"));

        //Create a DefaultListModelof Items (which is programmatically dynamic):
        final DefaultListModel<Item> listModel = new DefaultListModel<>();

        //Supply the model to the list on creation time (or later with setModel):
        final JList<Item> list = new JList<>(listModel);

        //Initialize the listModel to initially contain all items:
        allItems.forEach(item -> listModel.addElement(item));

        final JTextField searchField = new JTextField(10);
        final JButton searchButton = new JButton("Search");
        searchButton.addActionListener(e -> {
            final String searchText = searchField.getText();
            listModel.clear();
            if (searchText.isEmpty()) //If the search text field is empty, lets say we want to display all values:
                allItems.forEach(item -> listModel.addElement(item));
            else
                allItems.forEach(item -> {
                    if (item.getName().equalsIgnoreCase(searchText))
                        listModel.addElement(item);
                });
        });
        final JPanel pageStart = new JPanel(); //FlowLayout
        pageStart.add(searchField);
        pageStart.add(searchButton);
        final JPanel all = new JPanel(new BorderLayout());
        all.add(pageStart, BorderLayout.PAGE_START);
        all.add(new JScrollPane(list), BorderLayout.CENTER);
        final JFrame frame = new JFrame("Searchable JList");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(all);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}