我是 Java 代码的初学者，最近遇到了一个关于我的 Edit GUI JDialog 的问题。我正在做一项任务，它收集 DVD 上的信息并将其添加到主 GUI 的 JList 中。虽然到目前为止一切似乎都在工作，但唯一的问题是编辑 GUI。用户应在主 GUI 的 JList 中选择一个对象，然后单击编辑按钮以打开一个 JDialog 供用户编辑驻留在该对象中的信息。这不起作用，并一直说用户必须在 JList 中选择一个对象来编辑，即使用户已经选择或没有选择一个对象。
我在下面提供了我的所有代码：
主界面：
public class DVDGUI extends javax.swing.JFrame {
private DVDCollection dvdcollection = new DVDCollection();
public DVDGUI() {
initComponents();
loadData();
}
private void loadData()
{
try
{
ObjectInputStream infile = new ObjectInputStream(new FileInputStream("heatherdunne.txt"));
dvdcollection = (DVDCollection)infile.readObject();
infile.close();
updateDVDList();
}
catch (Exception e)
{
JOptionPane.showMessageDialog(this,"Error found - " + e);
}
}
public void saveData()
{
try
{
ObjectOutputStream outfile = new ObjectOutputStream(new FileOutputStream("heatherdunne.txt"));
outfile.writeObject(dvdcollection);
outfile.close();
System.exit(0);
}
catch (Exception e)
{
JOptionPane.showMessageDialog(this,"Error writing file - " + e);
}
}
@SuppressWarnings("unchecked")
private void lstDVDsValueChanged(javax.swing.event.ListSelectionEvent evt) {
if (lstDVDs.getSelectedIndex() >= 0)
txtDetails.setText(((DVD)lstDVDs.getSelectedValue()).getDetails());
else
txtDetails.setText(" ");
int selectedIndex = lstDVDs.getSelectedIndex();
ListModel lModel= lstDVDs.getModel();
DVD item = (DVD)lModel.getElementAt(selectedIndex);
System.out.println("Title= "+ item.getTitle());
boolean favourite = false;
favourite = true;
favourite = item.favourite;
if (item.favourite == true)
uebbtnFav.setSelected(true);
else
uebbtnFav.setSelected(false);
}
private void btnEditActionPerformed(java.awt.event.ActionEvent evt) {
if (lstDVDs.getSelectedIndex() >= 0)
{
JOptionPane.showMessageDialog(this,"You need to select a DVD to be edited");
}
else
{
DVD dvvvd = (DVD)lstDVDs.getSelectedValue();
EditDVD idk = new EditDVD(this, dvvvd);
}
}
private void loadDVDsfromfile(){
DVD dvd = null;
DVD dvd2 = null;
DVD dvd3 = null;
try
{
FileInputStream file = new FileInputStream("C:\\Users\\User\\Desktop\\code\\Assign2\\heatherdunne.txt");
ObjectInputStream in = new ObjectInputStream(file);
dvd = (DVD)in.readObject();
dvd2 = (DVD)in.readObject();
dvd3 = (DVD)in.readObject();
dvdcollection.addDVD(dvd);
dvdcollection.addDVD(dvd2);
dvdcollection.addDVD(dvd3);
in.close();
file.close();
System.out.println("Object has been deserialized ");
System.out.println(dvd);
System.out.println(dvd2);
System.out.println(dvd3);
}
catch(IOException ex)
{
System.out.println("IOException is caught");
}
catch(ClassNotFoundException ex)
{
System.out.println("ClassNotFoundException is caught");
}
}
private void formWindowOpened(java.awt.event.WindowEvent evt) {
loadDVDsfromfile();
DefaultListModel lstmdl = new DefaultListModel();
lstmdl.addElement(dvdcollection.getDVDs().get(0));
lstDVDs.setModel(lstmdl);
}
private void crtFileActionPerformed(java.awt.event.ActionEvent evt) {
DVD dvd = new DVD("Avengers: Endgame", 2019, Boolean.TRUE);
DVD dvd2 = new DVD("Shrek 2", 2004, Boolean.TRUE);
DVD dvd3 = new DVD("IT", 2017, Boolean.TRUE);
try
{
FileOutputStream file = new FileOutputStream("C:\\Users\\User\\Desktop\\code\\Assign2\\heatherdunne.txt");
ObjectOutputStream out = new ObjectOutputStream(file);
out.writeObject(dvd);
out.writeObject(dvd2);
out.writeObject(dvd3);
out.close();
file.close();
System.out.println("Object has been serialized");
}
catch(IOException ex)
{
System.out.println("IOException is caught");
}
}
public void updateDVDList()
{
if (rbtTitle.isSelected())
sortByTitle();
else
sortByID();
lstDVDs.setListData(dvdcollection.getDVDs().toArray());
}
编辑 DVD 图形用户界面
private DVD selectedDVD;
public EditDVD(DVDGUI inParent, DVD inDVD)
{
super(inParent, true);
initComponents();
parent = inParent;
Title.setText(selectedDVD.getTitle());
Year.setText(selectedDVD.getYear() + "");
setVisible(true);
}
@SuppressWarnings("unchecked")
private void EditActionPerformed(java.awt.event.ActionEvent evt) {
String title = Title.getText();
String year = Year.getText();
String msgTitle = DVD.checkTitle(title);
String msgYear = DVD.checkYear(year);
if (msgTitle.length()>0)
JOptionPane.showMessageDialog(this, msgTitle);
else
if (msgYear.length()>0)
JOptionPane.showMessageDialog(this, msgYear);
else
{
//validation was ok
selectedDVD.setTitle(title);
selectedDVD.setYear(Integer.parseInt(year));
parent.updateDVDList();
JOptionPane.showMessageDialog(this, "Update sucessful");
dispose();
}
}
DVD类：
public class DVD implements Serializable
{
private String id;
private String title;
private int year;
boolean favourite;
private int nextID=1;
public DVD(String inID, String inTitle, int inYear, boolean inFavourite)
{
id = inID;
title = inTitle;
year = inYear;
favourite = inFavourite;
}
public DVD (String inTitle, int inYear, boolean inFavourite)
{
id = "0";
nextID++;
title = inTitle;
year = inYear;
favourite = inFavourite;
}
public String toString()
{
return title;
}
public String getID()
{
return id;
}
public void setID(String inID)
{
id = inID;
}
public String getDetails()
{
return "id(" + id + ") " + title + " <" + year + "> ";
}
public String getTitle()
{
return title;
}
public void setTitle(String inTitle)
{
title = inTitle;
}
public String getYear()
{
if (year==0)
return " ";
else
return year + "";
}
public void setYear(int inYear)
{
year = inYear;
}
public boolean isFavourite()
{
return favourite;
}
public void setFavourite(boolean inFavourite)
{
favourite = inFavourite;
}
public static String checkTitle(String inTitle)
{
if (inTitle.trim().length()>0)
return "";
else
return "Title must have at least 1 non-blank character";
}
public static String checkYear(String inYear)
{
Calendar now = Calendar.getInstance();
int currYear = now.get(Calendar.YEAR);
try
{
int year = Integer.parseInt(inYear);
if ((year >= 1997)&&(year <= currYear))
return "";
else
return "Year must be between 1997 and current year";
}
catch (Exception ex)
{
return "Year must be a 4 digit integer";
}
}
public static String checkID(String inID)
{
if (inID.trim().length()>0)
return "";
else
return "ID must have at least 1 non-blank character";
}
public static boolean checkFavourite(boolean inFav)
{
boolean Favs = false;
int total = 0;
if ( !Favs )
{
total = total + 1;
}
return false;
}
public int compareTo(DVD d2)
{
// if (ID<c2.getID())
// return -1;
// else
// if (ID>c2.getID())
// return 1;
// else return 0;
return id.compareTo(d2.getID());
}
}
DVDCollection 类：
public class DVDCollection implements Serializable
{
private ArrayList<DVD> dvds = new ArrayList<DVD>();
private int nextID=1;
public boolean addDVD(DVD inDVD)
{
return
dvds.add(inDVD);
}
public DVDCollection()
{
}
public ArrayList<DVD> getDVDs()
{
return dvds;
}
public int getNumDVDs()
{
return dvds.size();
}
public boolean deleteDVD(DVD inDVD)
{
return dvds.remove(inDVD);
}
public int CountFavourites()
{
int total = 0;
if (DVD.checkFavourite(true))
{
boolean fav = true;
int val = fav? 1 : 0;
total = 1 + total;
}
else
{
boolean fav = false;
int val = fav? 1 : 0;
}
return total;
}
}
我已按照课堂上提供的编辑 GUI 的步骤进行操作，但仍然出现此问题。我尝试但取出的另一件事是将所有变量转换为字符串，并取出最喜欢的 jcheckbox 的编辑功能，以防万一出现问题。我做了更多的工作，但都导致了失败，并且仍然出现了同样的问题。
所有帮助将不胜感激
更新：问题已解决