cvc-elt.1：找不到元素“xs:schema”的声明

Question

i tried writing a simple XML document, but I am getting this error

Exception: cvc-elt.1: Cannot find the declaration of element 'xs:schema'. false

This is my XML

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMALSchema">
   <xs:element name="persons">
      <xs:complexType>
         <xs:sequence>
            <xs:element name="person">
               <xs:complexType>
                  <xs:sequence>
                     <xs:element name="name" type="xs:string" />
                     <xs:element name="age" type="xs:integer" />
                     <xs:element name="gender" type="xs:string" />
                     <xs:element name="address">
                        <xs:sequence>
                           <xs:element name="doorno" type="xs:integer" />
                           <xs:element name="street" type="xs:string" />
                           <xs:element name="city" type="xs:string" />
                           <xs:element name="state" type="xs:string" />
                        </xs:sequence>
                     </xs:element>
                     <xs:element name="student" minOccurs="0">
                        <xs:complexType>
                           <xs:sequence>
                              <xs:element name="rollno" type="xs:integer" />
                              <xs:element name="standard" type="xs:integer" />
                              <xs:element name="section" type="xs:string" />
                           </xs:sequence>
                        </xs:complexType>
                     </xs:element>
                     <xs:element name="staff" minOccurs="0">
                        <xs:complexType>
                           <xs:sequence>
                              <xs:element name="staffid" type="xs:integer" />
                              <xs:element name="subject" type="xs:string" />
                           </xs:sequence>
                        </xs:complexType>
                     </xs:element>
                  </xs:sequence>
               </xs:complexType>
            </xs:element>
         </xs:sequence>
      </xs:complexType>
   </xs:element>
</xs:schema>

Can you help me to give the missing declaration for <xs:schema> ?

Answer 1

The file you have shown us is a schema - or it would be, if you corrected the namespace URI. The error message, and the form of your question, suggest that you are treating it as an XML instance document that needs to be validated.

It is possible to validate a schema document (against the schema-for-schema-documents) but it is not a normal thing to do. Somehow this is what you are trying to do, and it's failing because the processor doesn't know where to find the schema-for-schema-documents.

It's not clear what exactly you are doing (when you get this error) but somehow it is confusing the XML instance document with the schema to be used for validation.