我的 JMenuBar 有问题。我使用下面的代码添加了图像。我想在文件菜单下退出-图像号。 1(如下拉菜单)和编辑选项卡下的插入 - 图像 2。由于某种原因，女巫也应该在编辑选项卡下没有显示 - 第 3 号图像。当您将鼠标悬停在编辑菜单中的搜索上时，我希望显示 4、5 和 6 号图像。我认为所有这些点都是相关的。谁能看到我的错误吗？希望图片有助于让我的问题更清楚，提前致谢!
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class DVD1 extends JFrame implements ActionListener
{
//construct components
JLabel sortPromt= new JLabel("Sort by:");
JComboBox fieldCombo= new JComboBox();
JTextPane textPane = new JTextPane();
//initalize data in arrays
String title[]={"Casablanca", "Citizen Kane", "Singin in the rain", "The wizzard of Oz"};
String studio[]={"Wanner Brothers", "RKO Pictures", "MGM", "MGM"};
String year[]={"1942", "1941", "1952", "1939"};
//construct an instance of DVD
public DVD1()
{
super("Classic on DVD");
}
//create the menu system
public JMenuBar createMenuBar()
{
///create instance of menu bar
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 JMenuItem("Exit");
mnuFileExit.setMnemonic(KeyEvent.VK_E);
mnuFileExit.setDisplayedMnemonicIndex(1);
mnuBar.add(mnuFileExit);
mnuFileExit.setActionCommand("Exit");
mnuFileExit.addActionListener(this);
//construct and pop 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(1);
mnuBar.add(mnuEditInsert);
mnuEditInsert.setActionCommand("Insert");
mnuEditInsert.addActionListener(this);
JMenu mnuEditSearch = new JMenu("Search",true);
mnuEditSearch.setMnemonic(KeyEvent.VK_R);
mnuEditSearch.setDisplayedMnemonicIndex(3);
mnuEditSearch.add(mnuEditSearch);
JMenuItem mnuEditSearchByTitle =new JMenuItem("By Title");
mnuEditSearchByTitle.setMnemonic(KeyEvent.VK_T);
mnuEditSearchByTitle.setDisplayedMnemonicIndex(3);
mnuBar.add(mnuEditSearchByTitle);
mnuEditSearchByTitle.setActionCommand("title");
mnuEditSearchByTitle.addActionListener(this);
JMenuItem mnuEditSearchByStudio =new JMenuItem("By Studio");
mnuEditSearchByStudio.setMnemonic(KeyEvent.VK_S);
mnuEditSearchByStudio.setDisplayedMnemonicIndex(3);
mnuBar.add(mnuEditSearchByStudio);
mnuEditSearchByStudio.setActionCommand("title");
mnuEditSearchByStudio.addActionListener(this);
JMenuItem mnuEditSearchByYear =new JMenuItem("By Year");
mnuEditSearchByYear.setMnemonic(KeyEvent.VK_Y);
mnuEditSearchByYear.setDisplayedMnemonicIndex(3);
mnuBar.add(mnuEditSearchByYear);
mnuEditSearchByYear.setActionCommand("title");
mnuEditSearchByYear.addActionListener(this);
return mnuBar;
}//End menu contructor
//Create the conetnt 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 arow to display sort fields");
//construct and populate the north panel
JPanel northPanel = new JPanel();
northPanel.setLayout(new FlowLayout());
northPanel.add(sortPromt);
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;
}//end create container method
//method to create thtab stops and set fontstyles
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 Style
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("blod",regular);
StyleConstants.setBold(s,true);
s = textPane .addStyle("lard",regular);
StyleConstants.setFontSize(s,16);
}
//method to ad text to textpane
public JTextPane addTextToTextPane()
{
Document doc = textPane.getDocument();
try
{
//clear 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] + "\n",textPane.getStyle("regular"));
}//end loop
} //end try
catch (BadLocationException ble)
{
System.err.println("Couldnlt Insert Text");
}//end catch
return textPane;
}///end addtexttotextpane method
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;
}//end swictch
} //end if
//user clicks exit on file menu
if (arg=="Exit")
System.exit(0);
//user clicks insert new dvd on edit menu
if (arg=="insert")
{
String newTitle = JOptionPane.showInputDialog(null, "Please enter the moive'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 to arrys
title[title.length-1] = newTitle;
studio[studio.length-1] = newStudio;
year[year.length-1] = newYear;
//call to sort method
sort(title);
fieldCombo.setSelectedIndex(0);
}//end if
//user clicks title on search submeu
if(arg=="title")
search(arg,title);
//user clicks title on studio submeu
if(arg=="studio")
search(arg,studio);
//user clicks title on year submeu
if(arg=="year")
search(arg,year);
}//end of actionPerfomed method
//Method to enlarge an arry 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;
}//end enlarg arry method
//method to sort arrays
public void sort(String tempArray[])
{
//loop to 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(studio,element, element+1);
}//end if
}//end of loop
addTextToTextPane();
}//end of sort method
//method to swap two elements of an array
public void swap(String swapArray[], int first, int second)
{
String hold;//temp area to hold for swap
hold = swapArray[first];
swapArray[first] = swapArray[second];
swapArray[second] = hold;
} //end swap method
public void search (String searchField, String searchArray[])
{
try
{
Document doc = textPane.getDocument();//assing text to document object
doc.remove(0,doc.getLength());//clear previous text
//display colomTitles
doc.insertString(0,"TITLE\tSTUDIO\tYEAR\n",textPane.getStyle("large"));
//Prompt users 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] + "\n", textPane.getStyle("regular"));
}//end if
}//end for
if (found = false)
{
JOptionPane.showMessageDialog(null,"Your search produced no results.", "no results found", JOptionPane.INFORMATION_MESSAGE);
sort(title);
}//end if
}//end try
catch(BadLocationException ble)
{
System.err.println("Couldn't insert text.");
}//end catch
}//End serach method
//main method executes at runtime
public static void main(String args[])
{
JFrame.setDefaultLookAndFeelDecorated(true);
DVD1 f =new DVD1();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setJMenuBar(f.createMenuBar());
f.setContentPane(f.createContentPane());
f.setSize(600,375);
f.setVisible(true);
}//end main method
}//end dvd class
最佳答案
实际上，您正在尝试将菜单项直接插入到 MenuBar，而不是其 Menu。您应使用:
JMenu.add(JMenuItem menuItem)
而不是
JMenuBar.add(JMenu menu)
代码示例:
mnuFile.add(mnuFileExit); // instead of mnuBar.add(mnuFileExit);
其他菜单项依此类推。
关于java - Java swing 应用程序中 JMenuBar Flyout 的问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23595413/