我正在跟随我的课本，试图学习如何在Java中创建窗口化应用程序和使用布局管理器。我已经使用textpad输入了代码，就像书中显示的那样，但是我的应用程序中并没有显示所有内容。该应用程序是预订派对室的程序。它显示8个面板预订吸烟和非吸烟房间。有一个客人数量的选择列表，两个吸烟和非吸烟复选框，2个文本字段的名称和电话号码和一个预订房间的按钮。我已经输入了代码如何在书中显示，唯一显示的是2文本字段，选项列表和书房按钮。谁能告诉我我做错了什么。没有编译错误。 这是我的名为Rooms的外部类：
public class Rooms{
//declaring variables
int numSmoking;
int numNonSmoking;
boolean occupied[];
//method for rooms
public Rooms(int non, int sm){
occupied = new boolean[sm+non];
//for loop for array occupied
for(int i=0; i < (sm+non); i++)
occupied[i] = false; //set each occupied room to false or empty
//initialize the number of smoking and non smoking rooms
numSmoking = sm;
numNonSmoking = non;
}//end method rooms
//method to book room
public int bookRoom(boolean smoking){
int begin, end;
int roomNumber=0;
//if statement for non smoking and smoking room booking
if(!smoking){
begin = 0;
end = numNonSmoking;
}//end if
else{
begin = numNonSmoking;
end = numSmoking+numNonSmoking;
}//end else
for (int i=begin; i < end; i++){
if(!occupied[i]){//if room not occupied
occupied[i] = true;
roomNumber = i+1;
i = end;//to exit loop
}//end if
}//end for
return roomNumber;
}//end method bookroom
}//ends class
这是我的主要课程，我命名为Module5example2：
import javax.swing.JOptionPane;
import java.awt.*;
import java.awt.event.*;
import java.awt.Color;
public class Module5example2 extends Frame implements
ActionListener{//
//creating color
Color lightRed = new Color(255, 90, 90);
Color lightGreen = new Color(140, 215, 40);
//variables
Rooms room = new Rooms(5, 3);
Panel roomPanel = new Panel();
TextArea roomDisplay[] = new TextArea[9];
Panel buttonPanel = new Panel();
Button bookButton = new Button("Book Room");
Panel inputPanel = new Panel();
Label custNameLabel = new Label("Name");
TextField nameField = new TextField(15);
Label custPhoneLabel = new Label("Phone Number");
TextField phoneField = new TextField(15);
Label numLabel = new Label("Number in Party");
Choice numberOfGuests = new Choice();
CheckboxGroup options = new CheckboxGroup();
Checkbox nonSmoking = new Checkbox("Nonsmoking",false,options);
Checkbox smoking = new Checkbox("Smoking",false,options);
Checkbox hidden = new Checkbox("",true,options);
//reservation method
public Module5example2(){// (B Reserv) constructor method
//set layouts for frame and three panels
this.setLayout(new BorderLayout());
roomPanel.setLayout(new GridLayout(2,4,10,10));
buttonPanel.setLayout(new FlowLayout());
inputPanel.setLayout(new FlowLayout());
//add components to room panel
for (int i=1; i<9; i++){ //(C for)
roomDisplay[i] = new TextArea(null,3,5,3);
if(i<6){
roomDisplay[i].setText("Room " + i + " Nonsmoking");
}
else{
roomDisplay[i].setText("Room " + i + " Smoking");
roomDisplay[i].setEditable(false);
roomDisplay[i].setBackground(lightGreen);
roomPanel.add(roomDisplay[i]);
}//end else
}//(C for closed)end for loop
//add components to button panel
buttonPanel.add(bookButton);
//add components to input label
inputPanel.add(custNameLabel);
inputPanel.add(nameField);
inputPanel.add(custPhoneLabel);
inputPanel.add(phoneField);
inputPanel.add(numLabel);
inputPanel.add(numberOfGuests);
for (int i = 8; i <= 20; i++)
numberOfGuests.add(String.valueOf(i));
inputPanel.add(nonSmoking);
inputPanel.add(smoking);
//add panels to frame
add(buttonPanel, BorderLayout.SOUTH);
add(inputPanel, BorderLayout.CENTER);
add(inputPanel, BorderLayout.NORTH);
bookButton.addActionListener(this);
//overriding the windowClosing() method will alow the user to click
//the close button
addWindowListener(
new WindowAdapter(){//
public void windowClosing(WindowEvent e){//
System.exit(0);
}//close window closing method
}// close window adapter
);
}//(end constructor method
//main
public static void main(String[] args){
Module5example2 f = new Module5example2();
f.setBounds(200,200,600,300);
f.setTitle("Reserve a Party Room");
f.setVisible(true);
}
public void actionPerformed(ActionEvent e){
if(hidden.getState()){
JOptionPane.showMessageDialog(null," You must select Nonsmoking or
Smoking.",
"Error", JOptionPane.ERROR_MESSAGE);
}
else{
int available = room.bookRoom(smoking.getState());
if (available > 0){//(end 2nd if)
roomDisplay[available].setBackground(lightRed);
roomDisplay[available].setText(
roomDisplay[available].getText()+
"\n" +
nameField.getText() +
" " +
phoneField.getText() +
"\nparty of" +
numberOfGuests.getSelectedItem()
);
clearFields();
}
else{ //room is not available
if (smoking.getState())
JOptionPane.showMessageDialog(null, "Smoking is full.","Error",
JOptionPane.INFORMATION_MESSAGE);
else
JOptionPane.showMessageDialog(null, "Nonsmoking is full.",
"Error",
JOptionPane.INFORMATION_MESSAGE);
hidden.setState(true);
}
}
}
//reset the text field choice components
void clearFields(){
nameField.setText("");
phoneField.setText("");
numberOfGuests.select(0);
nameField.requestFocus();
hidden.setState(true);
}//end void clearfield
}//(A Class closed)end class rexervations
答案 0 :(得分：0)
您忘了将roomPanel添加到JFrame。您需要将面板添加到JFrame才能显示它。 只是创建一个JPanel实例并设置属性不会有帮助。
所以你的代码需要修改为：
//add panels to frame
add(buttonPanel, BorderLayout.SOUTH);
add(inputPanel, BorderLayout.CENTER);
add(inputPanel, BorderLayout.NORTH);
add(roomPanel,BorderLayout.CENTER); //<----- You missed this.
修改 我只是建议如何在JFrames内容窗格上显示面板。当您从书籍/互联网上复制或阅读并输入内容时，请确保您了解每行提供的内容/原因。 再次，您只看到3个绿色框，因为您的for循环中有一个错误，要向面板添加房间框。因为
if(i<6){
roomDisplay[i].setText("Room " + i + " Nonsmoking");
}
您正在跳过添加前6个框到面板。我不确定这是否是一个＆＃34;业务＆＃34;要求所以我不能进一步评论。