Java中的范圍變量。 如何在一個范圍內鏈接兩個變量？
[英]Scoped variables in Java. How to link two variables within one scope?
問題描述
我正在嘗試調用存儲為會話范圍變量的變量。 如果我運行第一個if語句，則范圍變量調用將起作用。 當我運行else語句時，僅輸入一個名稱，不輸入任何地址（而是先前輸入的名稱和存儲的地址），則不返回與該名稱匹配的地址。 任何幫助將不勝感激，因為我對此有點迷惑。 謝謝
@WebServlet("/Test2") // tells server under which URL to offer this servlet
public class UserRegistration extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
// set content-type header before accessing the Writer
response.setContentType("text/html");
PrintWriter out = response.getWriter();
// then write the response
out.println("<html>" + "<head><title>Online Shopping Directory</title></head>");
//Get the identifier of the book to display
out.println("<body bgcolor=\"#ffffff\">"
+ "<h2>Please enter your name:</h2>" + "<form method=\"get\">"
+ "<input type=\"text\" name=\"username\" size=\"25\">"
+ "<p></p>"
+ "<h2>Please enter your address:</h2>" + "<form method=\"get\">"
+ "<input type=\"text\" name=\"useraddress\" size=\"25\">"
+ "<p></p>"
+ "<input type=\"submit\" value=\"Submit\">"
+ "<input type=\"reset\" value=\"Reset\">"
+ "</form>");
String name = request.getParameter("username");
String address = request.getParameter("useraddress");
HttpSession session = request.getSession();
session.setAttribute("username", address);
if ((name != null) && (name.length() > 0) && (address != null) && (address.length() > 0)) {
out.println("The username " + name + " has been saved for "
+ "this session. The address of this user is "
+ (String) session.getAttribute("username"));
} else if ((name == "username") && (address == null)) {
out.println("The username " + name + " is already saved. The address of this user is " + (String) session.getAttribute("username"));
}
out.println("</body></html>");
out.close();
}
}
1 個解決方案
解決方案1
0 已采納 2014-02-01 19:17:29
我認為您應該使用等於而不是==
if ((name.equals("username")) && (address.equals(""))) {
out.println("The username " + name + " is already saved. The address of this user is " + (String) session.getAttribute("username"));
}
在Java中獲取變量值的問題。 變量范圍
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