Question

有人可以解释这段代码中的错误吗？我正在尝试将数据从JList复制到另一个JList。我想知道，如何以及为什么......

public class Ex3 extends JFrame{
    private JList lista;
    private JList listaCopia;
    private static final String[] cores ={"Azul","Verde","Amarelo"};
    private static final  Color[] cor ={Color.blue,Color.green,Color.yellow};
    private JButton copiar; 

    public Ex3(){
        super("Utilizando JList");
        copiar = new JButton(" Copiar >>>> ");
        lista = new JList<String>(cores);
        setLayout(new FlowLayout());
        lista.setVisibleRowCount(3); // definida linhas visíveis
        lista.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION); // método de seleção única de opções
        add(lista);     
        add(copiar);
        copiar.addActionListener(           
                new ActionListener() {          
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        listaCopia.setListData(lista.getSelectedValuesList().toArray());                      
                    }
            });             
        lista.addListSelectionListener(new ListSelectionListener() {            
            @Override
            public void valueChanged(ListSelectionEvent e) {
                getContentPane().setBackground(cor[lista.getSelectedIndex()]);

            }
        });
        listaCopia = new JList<String>();
        listaCopia.setVisibleRowCount(3);
        listaCopia.setFixedCellWidth(100);
        listaCopia.setFixedCellHeight(15);
        add(new JScrollPane(listaCopia));       
    }
}

我找到了Java - Deprecated method - What to do?的方式，但没有解释...... 我只编译了另一个代码using getSelectedValuesList()，并且没有工作......为什么？

Answer 1

似乎适合我。当我移动/选择所有项目并单击copiar按钮时，左侧的所有项目都会复制到右侧的项目中。这不是你想要的吗？

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.ListSelectionModel;
import javax.swing.SwingUtilities;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

public class Ex3 extends JFrame {

    private JList lista;
    private JList listaCopia;
    private static final String[] cores = {"Azul", "Verde", "Amarelo"};
    private static final Color[] cor = {Color.blue, Color.green, Color.yellow};
    private JButton copiar;
    DefaultListModel model;

    public Ex3() {
        super("Utilizando JList");
        copiar = new JButton(" Copiar >>>> ");

        lista = new JList(cores);
        setLayout(new FlowLayout());
        lista.setVisibleRowCount(3); // definida linhas visíveis
        lista.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION); // método de seleção única de opções
        add(lista);
        add(copiar);
        copiar.addActionListener(
                new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                       listaCopia.setListData(lista.getSelectedValuesList().toArray());
                    }
                });
        lista.addListSelectionListener(new ListSelectionListener() {
            @Override
            public void valueChanged(ListSelectionEvent e) {
                getContentPane().setBackground(cor[lista.getSelectedIndex()]);

            }
        });
        listaCopia = new JList<String>();
        listaCopia.setVisibleRowCount(3);
        listaCopia.setFixedCellWidth(100);
        listaCopia.setFixedCellHeight(15);
        add(new JScrollPane(listaCopia));
    }

    private static void createAndShowGui() {
        Ex3 frame = new Ex3();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);

    }


    public Dimension getPreferredSize() {
        return new Dimension(300, 300);
    }

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

如果您只想一次添加一个元素。您应该使用ListModel。这是我为此做出的改变

public class Ex3 extends JFrame {

    private JList lista;
    private JList listaCopia;
    private static final String[] cores = {"Azul", "Verde", "Amarelo"};
    private static final Color[] cor = {Color.blue, Color.green, Color.yellow};
    private JButton copiar;
    DefaultListModel model;          <-- DefaultListModel

    public Ex3() {
        super("Utilizando JList");
        copiar = new JButton(" Copiar >>>> ");

        lista = new JList(cores);
        setLayout(new FlowLayout());
        lista.setVisibleRowCount(3); // definida linhas visíveis
        lista.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION); // método de seleção única de opções

        add(lista);
        add(copiar);

        listaCopia = new JList<String>();
        listaCopia.setVisibleRowCount(3);
        listaCopia.setFixedCellWidth(100);
        listaCopia.setFixedCellHeight(15);
        add(new JScrollPane(listaCopia));

        model = new DefaultListModel();         <-- initialize model
        listaCopia.setModel(model);             <-- set model

        copiar.addActionListener(
                new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                       //listaCopia.setListData(lista.getSelectedValuesList().toArray());
                       model.addElement(lista.getSelectedValue());   <-- Add to model
                    }
                });
        lista.addListSelectionListener(new ListSelectionListener() {
            @Override
            public void valueChanged(ListSelectionEvent e) {
                getContentPane().setBackground(cor[lista.getSelectedIndex()]);

            }
        });

    }

您可以看到我添加模型的<--，并在模型中添加元素。

编辑：

“我使用getSelectedValuesList（）编译另一个代码，但是没有用...为什么？”

getSelectedValuesList()返回List，setListData需要传递数组参数。此外，当您setListData时，您无法一次只更改添加一项。为此，您需要使用该模型。

请参阅setListData() javadoc | getSelectedValuesList() javadoc

Java - JList，getSelectedValues方法的困难

1 个答案: