Java eclipse 错误 - 此行有多个标记 - URL 和 SAXException 无法解析为类型

Question

我正在编写一个 Java 代码来根据 XSD 文件验证 XML。Eclipse 在以下代码中显示 2 个错误。

Multiple Markers at this line -

URL cannot be resolved to a type

SAXException cannot be resolved to a type

import javax.xml.XMLConstants;
    import javax.xml.transform.Source;
    import javax.xml.transform.stream.StreamSource;
    import javax.xml.validation.*;
    
    public class xml_validator_class {
     
      public static void main(String argv[]) {
          URL schemaFile = new URL("xsdfile.xsd");
          Source xmlFile = new StreamSource(new File("xmlfile.xml"));
          SchemaFactory schemaFactory = SchemaFactory
              .newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
          Schema schema = schemaFactory.newSchema(schemaFile);
          Validator validator = schema.newValidator();
          try {
            validator.validate(xmlFile);
            System.out.println(xmlFile.getSystemId() + " is valid");
          } catch (SAXException e) {
            System.out.println(xmlFile.getSystemId() + " is NOT valid");
            System.out.println("Reason: " + e.getLocalizedMessage());
          }
          
          
      }
      
    }

请引用this link对于以下程序:

Answer 1

导入缺失的类，使不合格的类型可以在程序中使用

import java.net.URL;
import org.xml.sax.SAXException;