Java无法找到符号,Java无法在数组中找到我的符号?
问题描述:
这是我写这行代码时得到的错误。Java无法找到符号,Java无法在数组中找到我的符号?
symbol : variable isSeletecd
location: class java.lang.String
if (dorm[0].isSeletecd && meal[0].isSeletecd())
^
if (dorm[0].isSeletecd && meal[0].isSeletecd())
totalCharges.setText("2150.00");
程序:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
/**
The Main class creates the GUI for the Dorm and
Meal charges.
*/
public class Main extends JFrame
{
private JPanel dormPanel;
private JComboBox dormBox;
private JPanel mealPanel;
private JComboBox mealBox;
private JPanel totalChargesPanel;
private JPanel selectedMealPanel;
private JPanel buttonPanel;
private JButton calcButton;
private JLabel label1;
private JTextField totalCharges;
private String[] dorm = { "Allen Hall: $1,500 per semester",
"Pike Hall: $1,600 per semester",
"Farthing Hall: $1,200 per semester",
"University Suites: $1,800 pe r semester"};
private String[] meal = { "7 meals per week: $650 per semester",
"14 meals per week: $1,095 per semester",
"Unlimited meals: $1,500 per semester"};
/**
Constructor
*/
public Main()
{
super("Dormitory and Meal Plan");
// Specify an action for the close button.
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Create a BorderLayout manager.
setLayout(new BorderLayout());
// Create the dorm and meal panel.
buildDormPanel();
buildMealPanel();
buildSelectedTotalChargesPanel();
buildButtonPanel();
// Add the components to the content pane.
add(dormPanel, BorderLayout.WEST);
add(mealPanel, BorderLayout.EAST);
add(totalChargesPanel, BorderLayout.SOUTH);
add(buttonPanel, BorderLayout.NORTH);
// Pack the contents of the window and display it.
pack();
setVisible(true);
}
// The buildDormPanel method builds the dorm panel.
private void buildDormPanel()
{
// Create the dorm panel.
dormPanel = new JPanel();
dormBox = new JComboBox(dorm);
// Register the action listener.
dormBox.addActionListener(new ComboBoxListener());
// Add the dorm panel to the panel.
dormPanel.add(dormBox);
}
// The buildMealPanel method builds the meal panel.
private void buildMealPanel()
{
// Create the meal panel.
mealPanel = new JPanel();
mealBox = new JComboBox(meal);
// Register the action listener.
mealBox.addActionListener(new ComboBoxListener());
// Add the meal panel to the panel.
mealPanel.add(mealBox);
}
// The buttonPanel method builds the bottun panel.
private void buildButtonPanel()
{
// Create a panel.
buttonPanel = new JPanel();
// Create a button.
calcButton = new JButton("Calculate");
// Register an action listener with the button.
calcButton.addActionListener(new ButtonListener());
// Add the button to the panel.
buttonPanel.add(calcButton);
}
// The buildSelectedDormPanel builds the selected totalCharges panel.
private void buildSelectedTotalChargesPanel()
{
// Create the totalChargesPanel for the label.
totalChargesPanel = new JPanel();
label1 = new JLabel("Total charges per semester: ");
// Create the totalCharges textfield.
totalCharges = new JTextField (25);
totalCharges.setEditable(false);
// Add the totalChargesPanel to the panel.
totalChargesPanel.add(label1);
totalChargesPanel.add(totalCharges);
}
/** Private inner class that handles the event when the user
selects the dorm and meal boxes.
*/
private class ComboBoxListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
// Variables to hold the dorm, meal, and total charges.
String dorm = (String) dormBox.getSelectedItem();
String meal = (String) mealBox.getSelectedItem();
// Calculates the total.
totalCharges.setText(meal + dorm);
}
}
private class ButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
if (dorm[0].isSeletecd && meal[0].isSeletecd())
totalCharges.setText("2150.00");
}
}
public static void main(String[] args)
{
new Main();
}
}
答
dorm
meal
和包括字符串数组,有一个上没有java.lang.String
字段isSeletecd
或方法。
答
dorm
和meal
是字符串数组
没有为String
类没有的方法,但存在用于JComboBox
一个getSelectedIndex()
方法,其可以被用于获取索引没有当前选择的项目的在JComboBox
部件。
通过从
if (dorm[0].isSeletecd && meal[0].isSeletecd())
在ButtonListener
类
更换条件的if语句
if(dormBox.getSelectedIndex()==0 && mealBox.getSelectedIndex()==0)
将解决你的问题。
所以你ButtonListener
类现在将
private class ButtonListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
if(dormBox.getSelectedIndex()==0 && mealBox.getSelectedIndex()==0)
totalCharges.setText("2150.00");
}
}
Reffer getSelectedIndex()
以获取更多信息。
如何缩小受影响的代码部分? – frm 2011-02-11 00:07:27