こんにちは。ユーザーが自分の DVD コレクションをタイトル、スタジオ、または年で並べ替えることができる入門 Java コース用のアプリケーションを作成しました。このアプリケーションを使用すると、ユーザーは追加の DVD をコレクションに追加して、アレイを拡大することもできます。コードは適切にコンパイルされますが、タイトル、スタジオ、および年が混同されているため、明らかに何か問題があります。明確にするために、このコードは教科書からのものであり、コードに表示される正確なメソッド、パッケージなどを使用する必要があるラボの一部です。コードをより効率的にする方法についてアドバイスを求めているわけではありませんが (私が学習しているので歓迎します)、具体的には提供されたコードの何が問題で「スクランブル」が発生しているのかを教えてください。ここに私が持っているコードがあります:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class DVD extends JFrame implements ActionListener
{
// construct components
JLabel sortPrompt = new JLabel("Sort by:");
JComboBox fieldCombo = new JComboBox();
JTextPane textPane = new JTextPane();
// initialize data in arrays
String title[] = {"Casablanca", "Citizen Kane", "Singin' in the Rain", "The Wizard of Oz"};
String studio[] = {"Warner Brothers", "RKO Pictures", "MGM", "MGM"};
String year[] = {"1942", "1941", "1952", "1939"};
// construct instance of DVD
public DVD()
{
super("Classics on DVD");
}
// create the menu system
public JMenuBar createMenuBar()
{
// create an instance of the menu
JMenuBar mnuBar = new JMenuBar();
setJMenuBar(mnuBar);
// construct and populate the File menu
JMenu mnuFile = new JMenu("File", true);
mnuFile.setMnemonic(KeyEvent.VK_F);
mnuFile.setDisplayedMnemonicIndex(0);
mnuBar.add(mnuFile);
JMenuItem mnuFileExit = new JMenu("Exit");
mnuFileExit.setMnemonic(KeyEvent.VK_X);
mnuFileExit.setDisplayedMnemonicIndex(1);
mnuFile.add(mnuFileExit);
mnuFileExit.setActionCommand("Exit");
mnuFileExit.addActionListener(this);
// contruct and populate the Edit menu
JMenu mnuEdit = new JMenu("Edit", true);
mnuEdit.setMnemonic(KeyEvent.VK_E);
mnuEdit.setDisplayedMnemonicIndex(0);
mnuBar.add(mnuEdit);
JMenuItem mnuEditInsert = new JMenuItem("Insert New DVD");
mnuEditInsert.setMnemonic(KeyEvent.VK_I);
mnuEditInsert.setDisplayedMnemonicIndex(0);
mnuEdit.add(mnuEditInsert);
mnuEditInsert.setActionCommand("Insert");
mnuEditInsert.addActionListener(this);
JMenu mnuEditSearch = new JMenu("Search");
mnuEditSearch.setMnemonic(KeyEvent.VK_R);
mnuEditSearch.setDisplayedMnemonicIndex(3);
mnuEdit.add(mnuEditSearch);
JMenuItem mnuEditSearchByTitle = new JMenuItem("by Title");
mnuEditSearchByTitle.setMnemonic(KeyEvent.VK_T);
mnuEditSearchByTitle.setDisplayedMnemonicIndex(3);
mnuEditSearch.add(mnuEditSearchByTitle);
mnuEditSearchByTitle.setActionCommand("title");
mnuEditSearchByTitle.addActionListener(this);
JMenuItem mnuEditSearchByStudio = new JMenuItem("by Studio");
mnuEditSearchByStudio.setMnemonic(KeyEvent.VK_S);
mnuEditSearchByStudio.setDisplayedMnemonicIndex(3);
mnuEditSearch.add(mnuEditSearchByStudio);
mnuEditSearchByStudio.setActionCommand("studio");
mnuEditSearchByStudio.addActionListener(this);
JMenuItem mnuEditSearchByYear = new JMenuItem("by Year");
mnuEditSearchByYear.setMnemonic(KeyEvent.VK_Y);
mnuEditSearchByYear.setDisplayedMnemonicIndex(3);
mnuEditSearch.add(mnuEditSearchByYear);
mnuEditSearchByYear.setActionCommand("year");
mnuEditSearchByYear.addActionListener(this);
return mnuBar;
}
// create the content pane
public Container createContentPane()
{
// populate the JComboBox
fieldCombo.addItem("Title");
fieldCombo.addItem("Studio");
fieldCombo.addItem("Year");
fieldCombo.addActionListener(this);
fieldCombo.setToolTipText("Click the drop-down arrow to display sort fields.");
// construct and populate the north panel
JPanel northPanel = new JPanel();
northPanel.setLayout(new FlowLayout());
northPanel.add(sortPrompt);
northPanel.add(fieldCombo);
// create the JTextPane and center panel
JPanel centerPanel = new JPanel();
setTabsAndStyles(textPane);
textPane = addTextToTextPane();
JScrollPane scrollPane = new JScrollPane(textPane);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
scrollPane.setPreferredSize(new Dimension(500, 200));
centerPanel.add(scrollPane);
// create Container and set attributes
Container c = getContentPane();
c.setLayout(new BorderLayout(10,10));
c.add(northPanel,BorderLayout.NORTH);
c.add(centerPanel,BorderLayout.CENTER);
return c;
}
// method to create tab stops and set font styles
protected void setTabsAndStyles(JTextPane textPane)
{
// create Tab Stops
TabStop[] tabs = new TabStop[2];
tabs[0] = new TabStop(200, TabStop.ALIGN_LEFT, TabStop.LEAD_NONE);
tabs[1] = new TabStop(350, TabStop.ALIGN_LEFT, TabStop.LEAD_NONE);
TabSet tabset = new TabSet(tabs);
// set Tab Style
StyleContext tabStyle = StyleContext.getDefaultStyleContext();
AttributeSet aset =
tabStyle.addAttribute(SimpleAttributeSet.EMPTY, StyleConstants.TabSet, tabset);
textPane.setParagraphAttributes(aset, false);
// set Font styles
Style fontStyle =
StyleContext.getDefaultStyleContext().getStyle(StyleContext.DEFAULT_STYLE);
Style regular = textPane.addStyle("regular", fontStyle);
StyleConstants.setFontFamily(fontStyle, "SansSerif");
Style s = textPane.addStyle("italic", regular);
StyleConstants.setItalic(s, true);
s = textPane.addStyle("bold", regular);
StyleConstants.setBold(s, true);
s = textPane.addStyle("large", regular);
StyleConstants.setFontSize(s, 16);
}
// method to add new text to the JTextPane
public JTextPane addTextToTextPane()
{
Document doc = textPane.getDocument();
try
{
// clear the previous text
doc.remove(0, doc.getLength());
// insert title
doc.insertString(0,"TITLE\tSTUDIO\tYEAR\n",textPane.getStyle("large"));
// insert detail
for (int j = 0; j<title.length; j++)
{
doc.insertString(doc.getLength(), title[j] + "\t", textPane.getStyle("bold"));
doc.insertString(doc.getLength(), studio[j] + "\t", textPane.getStyle("italic"));
doc.insertString(doc.getLength(), year[j] + "\t", textPane.getStyle("regular"));
}
}
catch(BadLocationException ble)
{
System.err.println("Couldn't insert text.");
}
return textPane;
}
// event to process user clicks
public void actionPerformed(ActionEvent e)
{
String arg = e.getActionCommand();
// user clicks the sort by combo box
if (e.getSource() == fieldCombo)
{
switch(fieldCombo.getSelectedIndex())
{
case 0:
sort(title);
break;
case 1:
sort(studio);
break;
case 2:
sort(year);
break;
}
}
// user clicks Exit on the File menu
if (arg == "Exit")
System.exit(0);
// user clicks Insert New DVD on the Edit Menu
if (arg == "Insert")
{
// accept new data
String newTitle = JOptionPane.showInputDialog(null, "Please enter the new movie's title");
String newStudio = JOptionPane.showInputDialog(null, "Please enter the studio for " + newTitle);
String newYear = JOptionPane.showInputDialog(null, "Please enter the year for " + newTitle);
// enlarge arrays
title = enlargeArray(title);
studio = enlargeArray(studio);
year = enlargeArray(year);
// add new data to arrays
title[title.length-1] = newTitle;
studio[studio.length-1] = newStudio;
year[year.length-1] = newYear;
// call sort method
sort(title);
fieldCombo.setSelectedIndex(0);
}
// user clicks Title on the Search submenu
if (arg == "title")
search(arg, title);
// user clicks Studio on the Search submenu
if (arg == "studio")
search(arg, studio);
// user clicks Year on the Search submenu
if (arg == "year")
search(arg, year);
}
// method to enlarge an array by 1
public String[] enlargeArray(String[] currentArray)
{
String[] newArray = new String[currentArray.length + 1];
for (int i = 0; i<currentArray.length; i++)
newArray[i] = currentArray[i];
return newArray;
}
// method to sort arrays
public void sort(String tempArray[])
{
// loop ton control number of passes
for (int pass = 1; pass < tempArray.length; pass++)
{
for (int element = 0; element < tempArray.length - 1; element++)
if (tempArray[element].compareTo(tempArray[element + 1])>0)
{
swap(title, element, element + 1);
swap(studio, element, element + 1);
swap(year, element, element + 1);
}
}
addTextToTextPane();
}
// method to swap two elements of an array
public void swap(String swapArray[], int first, int second)
{
String hold; // temporary holding area for swap
hold = swapArray[first];
swapArray[first] = swapArray[second];
swapArray[second] = hold;
}
public void search(String searchField, String searchArray[])
{
try
{
Document doc = textPane.getDocument(); // assign text to document object
doc.remove(0,doc.getLength()); // clear previous text
// display column titles
doc.insertString(0,"TITLE\tSTUDIO\tYEAR\n",textPane.getStyle("large"));
// prompt user for search data
String search = JOptionPane.showInputDialog(null, "Please enter the "+searchField);
boolean found = false;
// search arrays
for (int i = 0; i<title.length; i++)
{
if (search.compareTo(searchArray[i])==0)
{
doc.insertString(doc.getLength(), title[i] + "\t", textPane.getStyle("bold"));
doc.insertString(doc.getLength(), studio[i] + "\t", textPane.getStyle("italic"));
doc.insertString(doc.getLength(), year[i] + "\t", textPane.getStyle("regular"));
found = true;
}
}
if (found == false)
{
JOptionPane.showMessageDialog(null, "Your search produced no results.","No results found",JOptionPane.INFORMATION_MESSAGE);
sort(title);
}
}
catch(BadLocationException ble)
{
System.err.println("Couldn't insert text.");
}
}
// main method executes at run time
public static void main(String arg[])
{
JFrame.setDefaultLookAndFeelDecorated(true);
DVD f = new DVD();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setJMenuBar(f.createMenuBar());
f.setContentPane(f.createContentPane());
f.setSize(600,375);
f.setVisible(true);
}
}
これは、「スクランブル」の意味を理解するためのスクリーンショットです。
明らかに、すべてのタイトルは、タイトルの列、スタジオ内のスタジオ、年内の年にある必要があります。
いつものように、私は指導に感謝します。