このエラーが発生する理由..
Mar 29, 2013 2:04:26 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [com.jagrut.GroupServlet] in context with path [/jaagrut] threw exception
java.lang.NullPointerException
at com.jagrut.GroupServlet.doPost(GroupServlet.java:170)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
ここにコードがあります
try {
String queryString = "INSERT INTO groups(course_id,group_name,location,batch_no)"
+ " VALUES ('"
+ ccode
+ "','"
+ group
+ "','"
+ loc
+ "','" + batch + "')";
st = con.createStatement();
last_id = st.executeUpdate(queryString);
System.out.println(">>>>>>>llll" + last_id);
/* Getrting Group_id from groups table */
if(last_id == 0){
out.print("Group Already Available.");
//return;
}
try{
st1 = con.createStatement();
rs1 = st1.executeQuery("SELECT group_id from groups Where group_name='"+ group + "'");
while (rs1.next()) {
group_id = rs1.getInt(1);
}
System.out.print(">>>>>>>" + group_id);
/* Inserting DATA to Student Group */
}catch (SQLException ex1) {
System.out.print("Unable to Create Group.Duplicate Entry ");
ex1.printStackTrace();
}
try {
stmt1 = con.createStatement();
for (int i = 0; i < stud.length; i++) {
//System.out.println(stud[i]);
String sql = "Insert into student_group(group_id,s_id)Values('" + group_id + "','" + stud[i] + "')";
stmt1 = con.createStatement();
updateQuery = stmt1.executeUpdate(sql);
}
} catch (Exception ex1) {
out.println("Unable to Insert Student Into Group.");
ex1.printStackTrace();
}
/* Inserting teacher into the group */
try {
String query = "Insert into teacher_group(group_id,t_id,join_date)Values('" + group_id + "','" + teacher + "','" + sqlDate + "')";
st2 = con.createStatement();
updateQuery = st2.executeUpdate(query);
if (updateQuery != 0) {
out.println("Group Created Successfully");
}
} catch (Exception ex2) {
out.println("Unable to Insert Teacher Into Group.");
ex2.printStackTrace();
}
} catch (SQLException ex) {
out.print("Group Already Available.");
System.out.print("Unable to Create Group.Duplicate Entry ");
ex.printStackTrace();
}
finally {
// close all the connections.
try {
rs.close();
stmt.close();
st.close();
rs1.close();
stmt1.close();
st1.close();
st2.close();
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}