正如标题所示，我需要帮助来创建数据库。什么样的数据库数据库没关系，我只是需要它才能工作！
该程序是一个“音乐列表”，您可以添加歌曲，删除歌曲和编辑歌曲。
我已经编程了大约一个月，所以如果您还能解释数据库方法是如何工作的，我将不胜感激，而不仅仅是给我答案： - ）。
数据库需要存储3个ArrayLists的数据。 3个arraylists都存储了Strings，我使用JList（Model）的索引连接了arraylists。
我需要的功能是：
我不确定使用3个arraylists来存储数据是个好主意，所以如果有更好的选择，我会很高兴知道： - ）
当我从数据库调用数据时，应该将数据调用到方法addString（）。此方法需要3个字符串，并将它们添加到同一索引中。所以我猜数据库不应该包含任何类型的索引。
“edit”方法可以在editSong（）;中找到，而“remove”方法可以在ite.addActionListener中找到。
3数组是：fl，包含歌曲名称; art，其中包含艺术家姓名; youurl，其中包含youtube url。
以下是代码：
公共类MusicList扩展了JFrame {
public JTextField af;
private JList jl;
private JButton add;
private JButton edit;
private JButton test;
private JPanel jp;
private JScrollPane sp;
private JTextField artist;
private JButton save;
private JButton listb;
private JPopupMenu jpo;
private JMenuItem ite;
private JButton editsave;
private JButton editlist;
private JTextField youtube;
private JLabel ytl;
private JLabel arti;
private JLabel songg;
int g;
//creates a DefaultListModel.. actions at the JList can be made through here. e.g if adding to jlist is m.addElement();
DefaultListModel<String> m = new DefaultListModel<String>();
//creates arraylists
List<String> fl = new ArrayList<String>();
List<String> art = new ArrayList<String>();
List<String> youurl = new ArrayList<String>();
public MusicList(){
super("Musiclist - Alpha");
setLayout(null);
jl = new JList(m);
add(jl);
//creates a scrollpane, "implements jlist"
sp = new JScrollPane(jl);
sp.setBounds(30,30,195,200);
add(sp);
//creates the textfield to contain songname
af = new JTextField(12);
String afs = af.getText();
af.setBounds(20,30,210,20);
add(af);
af.setVisible(false);
//opens the add menu
add = new JButton("add song");
add.setBounds(20,250,100,20);
add(add);
//opens the edit menu
edit = new JButton("edit song");
edit.setBounds(135,250,100,20);
add(edit);
//this button checks if art and fl(arraylists) match to the index.
test = new JButton("test");
test.setBounds(300, 40, 80, 20);
add(test);
//the textfield which will pass the artist string.. used in add and edit
artist = new JTextField();
artist.setBounds(20,70,210,20);
add(artist);
artist.setVisible(false);
//adds back button in "add" menu
listb = new JButton("back");
listb.setBounds(135,250,100,20);
add(listb);
listb.setVisible(false);
//adds save button on "add" menu
save = new JButton("save");
save.setBounds(20,250,100,20);
add(save);
save.setVisible(false);
//adds the back button on "edit" menu
editlist = new JButton("back");
editlist.setBounds(135, 250, 100, 20);
add(editlist);
editlist.setVisible(false);
//adds the save button on "edit" menu
editsave = new JButton ("save");
editsave.setBounds(20,250,100,20);
add(editsave);
editsave.setVisible(false);
//adds the youtube textfield
youtube = new JTextField();
youtube.setBounds(20,110,120,20);
add(youtube);
youtube.setVisible(false);
//adds jlabel
ytl = new JLabel("https://www.youtube.com/watch");
ytl.setBounds(20,90,200,20);
add(ytl);
ytl.setVisible(false);
arti = new JLabel("Artist");
arti.setBounds(20,50,170,20);
add(arti);
arti.setVisible(false);
songg = new JLabel("Song");
songg.setBounds(20,10,170,20);
add(songg);
songg.setVisible(false);
//button to open the add window
add.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent event){
jl.setVisible(false);
sp.setVisible(false);
add.setVisible(false);
edit.setVisible(false);
listb.setVisible(true);
save.setVisible(true);
af.setVisible(true);
artist.setVisible(true);
youtube.setVisible(true);
ytl.setVisible(true);
songg.setVisible(true);
arti.setVisible(true);
af.requestFocus();
}});
edit.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent event){
System.out.println(jl.getSelectedIndex());
//checks if theres an selected index.. unselected index = -1.
if(jl.getSelectedIndex()<0){
JOptionPane.showMessageDialog(null, "Please select a song to edit");
}else{
//open edit window
jl.setVisible(false);
sp.setVisible(false);
add.setVisible(false);
edit.setVisible(false);
editlist.setVisible(true);
editsave.setVisible(true);
af.setVisible(true);
artist.setVisible(true);
youtube.setVisible(true);
ytl.setVisible(true);
songg.setVisible(true);
arti.setVisible(true);
//takes selected index, and set text of textfield af and artists to selected index.
final int i = jl.getSelectedIndex();
if(i>=0){
System.out.println(i);
af.setText(fl.get(i));
artist.setText(art.get(i));
youtube.setText(youurl.get(i));
}}}});
//test button.. checks if index + song + artist match.
test.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent event){
final int i = jl.getSelectedIndex();
if(i>=0){
//String j = (m.getElementAt(i));
//System.out.println(j);
System.out.println(fl.get(i));
System.out.println(art.get(i));
System.out.println(youurl.get(i));
}}});
jl.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent evt) {
//adds a actionlistener to Jlist
JList jl = (JList)evt.getSource();
//if double click---
if (evt.getClickCount() == 2) {
int index = jl.locationToIndex(evt.getPoint());
String url = ("https://www.youtube.com/watch"+youurl.get(index));
if(Desktop.isDesktopSupported()){
Desktop desktop = Desktop.getDesktop();
try {
desktop.browse(new URI(url));
} catch (IOException | URISyntaxException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else{
Runtime runtime = Runtime.getRuntime();
try {
runtime.exec("xdg-open " + url);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
} else if (evt.getClickCount() == 3) { // Triple-click
int index = jl.locationToIndex(evt.getPoint());
}}});
//listb is the "back to list" button.
listb.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent event){
//if u are at add window, listb will take u back to the list of songs.
jl.setVisible(true);
sp.setVisible(true);
add.setVisible(true);
edit.setVisible(true);
listb.setVisible(false);
save.setVisible(false);
af.setVisible(false);
artist.setVisible(false);
youtube.setVisible(false);
ytl.setVisible(false);
songg.setVisible(false);
arti.setVisible(false);
}});
save.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent event){
//takes the afart, and save it to the JList(first passed to addString)
String getart = artist.getText();
String getaf = af.getText();
String afart = (getaf+" - "+getart);
String yt = youtube.getText();
//pass afart to addString method
addString(getaf,getart,yt);
af.setText(null);
youtube.setText(null);
jl.requestFocus();
artist.setText(null);
//set the window back to "list of songs"
jl.setVisible(true);
sp.setVisible(true);
add.setVisible(true);
edit.setVisible(true);
listb.setVisible(false);
save.setVisible(false);
af.setVisible(false);
artist.setVisible(false);
youtube.setVisible(false);
ytl.setVisible(false);
songg.setVisible(false);
arti.setVisible(false);
}});
//adds another mouselistener to jl
jl.addMouseListener(
new MouseAdapter(){
public void mousePressed(MouseEvent e) {check(e);}
public void mouseReleased(MouseEvent e) {check(e);}
//mouse event right click
public void check(MouseEvent e) {
if (e.isPopupTrigger()) { //if the event shows the menu
jl.setSelectedIndex(jl.locationToIndex(e.getPoint())); //select the item
//creates a popupmenu.
JPopupMenu jpo = new JPopupMenu();
//creates a item that links to popupmenu.. JMenuItem works like a button
//this JMenuItem is a remove button
JMenuItem ite = new JMenuItem("remove");
jpo.add(ite);
jpo.show(jl, e.getX(), e.getY()); //and show the menu
//JMenuItem actionListener.
ite.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent e){
//takes selectedIndex, and remove it from the two arraylist, + the Modellist(jlist)
final int i = jl.getSelectedIndex();
if(i>=0){
m.removeElementAt(i);
fl.remove(i);
art.remove(i);
youurl.remove(i);
}}});}}});
//ActionListener for the back button in the edit menu
editlist.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent e){
jl.setVisible(true);
sp.setVisible(true);
add.setVisible(true);
edit.setVisible(true);
editlist.setVisible(false);
editsave.setVisible(false);
youtube.setVisible(false);
ytl.setVisible(false);
af.setVisible(false);
artist.setVisible(false);
songg.setVisible(false);
arti.setVisible(false);
youtube.setText(null);
af.setText(null);
artist.setText(null);
}});
//ActionListener for the save buttin in the edit menu
editsave.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent e){
//takes 2 string, and the int from getSelected index, and pass it to editSong(); method.
String aff = af.getText();
String artt = artist.getText();
String yte = youtube.getText();
final int f = jl.getSelectedIndex();
//System.out.println(f);
editSong(f,aff,artt,yte);
//close the edit window
jl.setVisible(true);
sp.setVisible(true);
add.setVisible(true);
edit.setVisible(true);
editlist.setVisible(false);
editsave.setVisible(false);
youtube.setVisible(false);
ytl.setVisible(false);
af.setVisible(false);
artist.setVisible(false);
songg.setVisible(false);
arti.setVisible(false);
youtube.setText(null);
af.setText(null);
artist.setText(null);
}});
}
//addString method adds new string to JList, and put them at the next avaiable index.
public void addString(String o, String l, String yt){
//adds the songname and artistname to the arratlist.
fl.add(o);
art.add(l);
youurl.add(yt);
String p = (o+" - "+l);
//adds the artists+songname to the jlist.
m.addElement(p.toString());
}
public void editSong(int i, String song, String artt,String yte){
String s = song;
String a = artt;
String sa = (s+" - "+a);
//fl.add(i,null);
//remove object at the indexnumber "i"(current index selected) from arraylists.
fl.remove(i);
art.remove(i);
youurl.remove(i);
//adds the new string passed in from "editsave", and put them to selectedIndex..
fl.add(i,s);
art.add(i,a);
youurl.add(i,yte);
//remove old JList element, and put in the new.
m.removeElementAt(i);
m.add(i,sa);
}
}
答案 0 :(得分：1)
我建议您再花一个月的时间来学习什么是MVC以及如何使用EventBus。关于这个有很多教程。 您还应该花费一个月的时间来真正关心数据库的工作原理以及它们的主要区别，因为它会改变您编写所有其他部分的方式。
要回答您的问题，您不应该在同一方法中修改视图，模型，然后在数据库中保存内容。如果您仍想这样做，最好的方法是使用JDO数据库，例如http://db.apache.org/jdo/或Google App Engine。
但是这样做的方法无法回答，这可能是一项过于复杂的任务。