update

distributed-print-business/src/main/java/com/qmth/distributed/print/business/entity/ExamStudent.java

@@ -9,6 +9,7 @@ import com.qmth.distributed.print.business.base.BaseEntity;
 import io.swagger.annotations.ApiModelProperty;
 
 import java.io.Serializable;
+import java.util.Objects;
 
 /**
  * <p>
@@ -103,7 +104,7 @@ public class ExamStudent extends BaseEntity implements Serializable {
     }
 
     public String getSiteNumber() {
-        return siteNumber;
+        return Objects.isNull(siteNumber) ? "" : null;
     }
 
     public void setSiteNumber(String siteNumber) {

distributed-print-business/src/main/java/com/qmth/distributed/print/business/util/CreatePdfUtil.java

@@ -145,21 +145,8 @@ public class CreatePdfUtil {
         htmlMap.put("proctorCollege", String.join(",", proctorCollege));
         htmlMap.put("examManager", String.join(",", examManager));
 
-        String minSite = examStudentList.stream().min((a, b) -> {
-            if (Objects.nonNull(a.getSiteNumber()) && Objects.nonNull(a.getSiteNumber())) {
-                return a.getSiteNumber().compareTo(b.getSiteNumber());
-            } else {
-                return 0;
-            }
-        }).get().getSiteNumber();
-
-        String maxSite = examStudentList.stream().max((a, b) -> {
-            if (Objects.nonNull(a.getSiteNumber()) && Objects.nonNull(a.getSiteNumber())) {
-                return a.getSiteNumber().compareTo(b.getSiteNumber());
-            } else {
-                return 0;
-            }
-        }).get().getSiteNumber();
+        String minSite = examStudentList.stream().min((a, b) -> a.getSiteNumber().compareTo(b.getSiteNumber())).get().getSiteNumber();
+        String maxSite = examStudentList.stream().max((a, b) -> a.getSiteNumber().compareTo(b.getSiteNumber())).get().getSiteNumber();
 
         htmlMap.put("minSite", minSite);
         htmlMap.put("maxSite", maxSite);