嘿,我正在制作一个航班预订系统,当我点击一个座位进行预订时出现这个错误“AWT-EventQueue-0”的座位时出现此错误 java.lang.NullPointerException我认为我的 2D 对象初始化有误... PS:有吗一种我可以摆脱final
前面的方法Seats[][] seats = new Seats[4][5];
这是我的座位类别:
public class Seats {
private int row_number;
private boolean booked;
private Passenger myPassenger;
private String seat_name;
private String type;
private int column_number;
private long booking_nr;
public Seats(){
myPassenger = new Passenger();
booked = false;
}
public boolean isBooked() {
return booked;
}
public void setBooked(boolean booked) {
this.booked = booked;
}
}
下面是我的图形用户界面:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
public class Book_GUI extends JFrame {
//private EconomyClass eco;
private JPanel contentPane;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Book_GUI frame = new Book_GUI();
frame.setTitle("Economy Class");
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public Book_GUI() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
int left = 3;
int middle = 3;
int right = 4;
String[] singleRowAll = new String [left+middle+right];
for(int i = 1;i<singleRowAll.length;i++){singleRowAll[i] = "";}
singleRowAll[0] = "Window";
singleRowAll[left-1] = "Aisle";
singleRowAll[left] = "Aisle";
singleRowAll[left+middle-1] = "Aisle";
singleRowAll[left+middle] = "Aisle";
singleRowAll[left+middle+right-1] = "Window";
//eco = new EconomyClass(4,5,3,3,4);
final Seats[][] seats = new Seats[4][10];
for ( int i = 0; i < 4; i++) {
char c= 'A';
for ( int j = 0; j < 10; j++) {
final int x = i;
final int z = j;
final JButton btnBookFlight = new JButton(" " + (i+1) + c++ + " " + singleRowAll[j] );
btnBookFlight.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
if(seats[x][z].isBooked()){btnBookFlight.setBackground(Color.GREEN);}
seats[x][z].setBooked(true);
//JButton button = (JButton)arg0.getSource();
//button.setBackground(Color.RED);
// btnBookFlight.setBackground(Color.RED);
btnBookFlight.setOpaque(true);
}
});
contentPane.add(btnBookFlight);
}
}
contentPane.setLayout(new GridLayout(4, 10));
pack();
}
}
感谢您的阅读和您的时间!