假设我有两个类A和B。如果我在B类创建类A的一个对象,并且还在A类创建类B的对象,它会导致堆栈溢出错误。一个解决这个问题是,我可以创建在B类,并且反之亦然的任何函数内部类A的目的,但如果我这样做,那么类的对象A创建每次该特定功能,其中类的对象A被创建,被调用。在java中创建对象 - stackoverflow错误
问题是我怎样才能使对象内部有效地彼此相对?A和B?
考虑下面的例子。
我创建房类的对象AddRoom类又创造AddRoom类的对象室教室类
public class Room {
String roomno;
String reserved;
String category;
String airconditioned;
String bedtype;
String rent;
Connection con;
PreparedStatement ps;
ResultSet rs;
AddRoom adr = new AddRoom();
RemoveRoom rr = new RemoveRoom();
UpdateRoom ur = new UpdateRoom();
// AllRooms alr = new AllRooms();
public Room()
{
roomno = "";
reserved = "";
category = "";
airconditioned = "";
bedtype = "";
rent = "";
make_connection();
}
public void make_connection()
{
try{
String driver = "net.ucanaccess.jdbc.UcanaccessDriver";
Class.forName(driver);
String login = "jdbc:ucanaccess://C:\\MsDatabase\\EmployeeDB.accdb";
con = DriverManager.getConnection(login);
}catch(Exception ex){ System.out.println(ex);}
}
public void add_room(AddRoom obj)
{
try{
adr = obj;
if("".equals(adr.get_jtextfield1().getText())||"".equals(adr.get_jtextfield2().getText())||
"".equals(adr.get_jtextfield3().getText())||"".equals(adr.get_jtextfield4().getText())||
"".equals(adr.get_jtextfield5().getText())||"".equals(adr.get_jtextfield6().getText()))
{
JOptionPane.showMessageDialog(null, "None of the fields can be left empty");
}
else
{
roomno = adr.get_jtextfield1().getText();
reserved = adr.get_jtextfield2().getText();
category = adr.get_jtextfield3().getText();
airconditioned = adr.get_jtextfield4().getText();
bedtype = adr.get_jtextfield5().getText();
rent = adr.get_jtextfield6().getText();
String sql = "INSERT INTO RoomInfo(RoomNumber,Reserved,RoomCategory,AirConditioned,BedType,RentPerDay)"
+ "VALUES(?,?,?,?,?,?)";
ps = con.prepareStatement(sql);
ps.setInt(1, new Integer(roomno));
ps.setString(2, reserved);
ps.setString(3, category);
ps.setString(4, airconditioned);
ps.setString(5, bedtype);
ps.setInt(6, new Integer(rent));
ps.executeUpdate();
JOptionPane.showMessageDialog(null, "Room Added Successfully");
}
}catch(Exception ex){
JOptionPane.showMessageDialog(null, "Input in Room Number and "
+ "Rent Per Day should be a number");
}
}
}
AddRoom类
public class AddRoom extends javax.swing.JFrame {
Room objr = new Room();
public AddRoom() {
initComponents();
}
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
//Room objr = new Room();
objr.add_room(this);
}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
AdminHome admh = new AdminHome();
admh.setVisible(true);
dispose();
}
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new AddRoom().setVisible(true);
}
});
}
public JTextField get_jtextfield1()
{
return jTextField1;
}
public JTextField get_jtextfield2()
{
return jTextField2;
}
public JTextField get_jtextfield3()
{
return jTextField3;
}
public JTextField get_jtextfield4()
{
return jTextField4;
}
public JTextField get_jtextfield5()
{
return jTextField5;
}
public JTextField get_jtextfield6()
{
return jTextField6;
}
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel4;
private javax.swing.JLabel jLabel5;
private javax.swing.JLabel jLabel6;
private javax.swing.JLabel jLabel7;
private javax.swing.JPanel jPanel1;
private javax.swing.JTextField jTextField1;
private javax.swing.JTextField jTextField2;
private javax.swing.JTextField jTextField3;
private javax.swing.JTextField jTextField4;
private javax.swing.JTextField jTextField5;
private javax.swing.JTextField jTextField6;
// End of variables declaration
}
注意。现在,如果我这样做,然后我得到堆栈溢出错误,但如果如果我使AddRoom类中的任何函数内的Room类的对象,然后堆栈溢出错误不显示和程序运行良好。
您可能想要将现有实例传递给其他类。 – SLaks
您不在这些类中创建任何对象。该代码不会导致堆栈溢出。 – Kayaman
@Kayaman我发布了一个代码示例,它给了我堆栈溢出错误。 – Yousaf