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我在學習servlets,我試圖創建這個基本的計算器。我試圖將所有例外添加到字符串中,並將該字符串作爲錯誤消息打印在網頁上。我只包括代碼腳本標記內的換行符
public class Calculator extends HttpServlet{
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String x = request.getParameter("x");
String y = request.getParameter("y");
DecimalFormat df = new DecimalFormat("#,###.##");
String errorMsg = "";
if (x != null && y == null) {
errorMsg = errorMsg.concat("Y cannot be blank\n");
}
else if (x == null && y != null) {
errorMsg = errorMsg.concat("X cannot be blank");
}
out.println("<!doctype html>");
out.println("<html>");
out.println("<head>");
out.println("<title>Calculator</title>");
out.println("</head>");
out.println("<body>");
if (!errorMsg.equalsIgnoreCase("")) {
out.println("<h2>"+errorMsg+"</h2>");
}
out.println("<form>");
out.println("<table border='1' style='background-color:#999'>");
out.println("<tr><td>X </td> <td><input type='text' id='xValue' name='x' /></td></tr>");
out.println("<tr><td>Y </td> <td><input type='text' id='yValue' name='y' /></td></tr>");
out.println("<tr><td colspan='2'>");
out.println("<input type='submit' id='plusButton' value='+' name='add' />");
out.println("<input type='submit' id='minusButton' value='-' name='sub' />");
out.println("<input type='submit' id='mulButton' value='*' name='mul' />");
out.println("<input type='submit' id='divButton' value='/' name='div' />");
out.println("</table>");
out.println("</form></body></html>");
}
}
的基本部分。如果我輸入字母時,X和Y文本框,我應該得到一個錯誤味精。更具體地說,我應該在兩個單獨的行上得到兩個錯誤消息。然而,我正在同一行上得到他們兩個。在命令行中,我將它們放在不同的行上。我在這裏做錯了什麼?
好的和明確的問題,歡迎來到StackOverflow! –