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jBCrypt String index out of range: 0 error on starting app in Netbeans

I'm receiving the following error in the Apache logs when starting my application
I've found BCrypt.checkpw() Invalid salt version exception
But this is not a match as the passwords stored in the DB for my users are hashed and this error appears on start up and I've no issues logging in 99.99% of the time.
29-Oct-2017 22:12:32.242 SEVERE [http-nio-8084-exec-1] org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [UserController] in context with path [/medsched] threw exception
java.lang.StringIndexOutOfBoundsException: String index out of range: 0
at java.lang.String.charAt(String.java:658)
at org.mindrot.jbcrypt.BCrypt.hashpw(BCrypt.java:658)
at org.mindrot.jbcrypt.BCrypt.checkpw(BCrypt.java:764)
at medsched.data.UserDB.loginUser(UserDB.java:216)
at medsched.controllers.UserController.logInToSite(UserController.java:165)
at medsched.controllers.UserController.doPost(UserController.java:41)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.filters.CsrfPreventionFilter.doFilter(CsrfPreventionFilter.java:213)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at medsched.filters.SecPageFilter.doFilter(SecPageFilter.java:61)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.logging.log4j.web.Log4jServletFilter.doFilter(Log4jServletFilter.java:71)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
It does not seem to affect the application as nearly most of the time as I can log in or if I present a password mismatch I am returned to a login error jsp defined in my application. I do some times, however receive a 500 error page with
java.lang.StringIndexOutOfBoundsException: String index out of range: 0
at java.lang.String.charAt(String.java:658)
at org.mindrot.jbcrypt.BCrypt.hashpw(BCrypt.java:658)
at org.mindrot.jbcrypt.BCrypt.checkpw(BCrypt.java:764)
at medsched.data.UserDB.loginUser(UserDB.java:216)
at medsched.controllers.UserController.logInToSite(UserController.java:165)
at medsched.controllers.UserController.doPost(UserController.java:41)
Could it be the way I'm using BCrypt.checkpw ?? I'd understand the error appearing if I was attempting to log in, but not on starting the application in Netbeans.
public static User loginUser(String phnum,String passw) {
ConnectionPool pool = ConnectionPool.getInstance();
Connection connection = pool.getConnection();
PreparedStatement ps = null;
ResultSet rs = null;
String hpwd="";
//Get the key
String key=confUtil.encDeckey();
String query = "SELECT userid,fName,pwd FROM users "
+ "WHERE phone = AES_ENCRYPT(?,?) AND active=1";
try {
ps = connection.prepareStatement(query);
ps.setString(1, phnum);
ps.setString(2, key);
rs = ps.executeQuery();
User user = null;
if (rs.next()) {
user = new User();
user.setUserID(rs.getLong("userid"));
user.setFName(rs.getString("fName"));
user.setPwd(rs.getString("pwd"));
hpwd=user.getPwd();
}
if(hpwd!=null || !hpwd.isEmpty()){
if(!BCrypt.checkpw(passw,hpwd)){
user=null;
}
}
} catch (SQLException e) {
//System.err.println(e);
log.error("Exception when trying to log in",e);
return null;
} finally {
DBUtil.closeResultSet(rs);
DBUtil.closePreparedStatement(ps);
pool.freeConnection(connection);
}
}
Issue occurred again today, posting the 500 error that I'm getting
HTTP Status 500 - String index out of range: 0
type Exception report
message String index out of range: 0
description The server encountered an internal error that prevented it from fulfilling this request.
exception
java.lang.StringIndexOutOfBoundsException: String index out of range: 0
java.lang.String.charAt(String.java:658)
org.mindrot.jbcrypt.BCrypt.hashpw(BCrypt.java:658)
org.mindrot.jbcrypt.BCrypt.checkpw(BCrypt.java:764)
medsched.data.UserDB.loginUser(UserDB.java:190)
medsched.controllers.UserController.logInToSite(UserController.java:169)
medsched.controllers.UserController.doPost(UserController.java:41)
javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
org.apache.catalina.filters.CsrfPreventionFilter.doFilter(CsrfPreventionFilter.java:213)
medsched.filters.SecPageFilter.doFilter(SecPageFilter.java:61)
org.apache.logging.log4j.web.Log4jServletFilter.doFilter(Log4jServletFilter.java:71)
note The full stack trace of the root cause is available in the Apache Tomcat/8.0.27 logs.

I just ran into a similar issue:
Bcrypt throws java.lang.StringIndexOutOfBoundsException: String index out of range: 0.
In my case I found out that the hashed password was empty.
I can't tell why this error is appearing at app start without seeing more code.

JSP, Integer.parseInt throw error even when testing for null

here is the code
if(var!=null) {
int varInt= Integer.parseInt(var);
method.setProp(varInt);
}
After some reseach it normally throw error when we're not testing for null, but I am, so what's the problem?
The Error
org.apache.jasper.JasperException: An exception occurred processing JSP page /TravelSearch.jsp at line 81
80: if(var!=null) {
81: int varInt= Integer.parseInt(var);
82: method.setProp(varInt);
83: }
84:
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:567)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:469)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
cause mère
java.lang.NumberFormatException: For input string: ""

Take a look at this answer by Jon Skeet.
https://stackoverflow.com/a/1486082/891261
This is what you want - a method that checks if the string can be parsed to a number and returns an obvious illegal value when it does not, which you then can check for and act on.

The number you're trying to parse isn't null, it's an empty string "". The stacktrace was telling you this here:
java.lang.NumberFormatException: For input string: ""
Change your test to do this:
if(var!=null && !"".equals(var)) {

HTTP Status 500 - An exception occurred processing JSP page /FinancialAssessment.jsp at line 440

Following is the exact error.
Type Exception report:
message An exception occurred processing JSP page /FinancialAssessment.jsp at line 440
Description:
The server encountered an internal error that prevented it from fulfilling this request.
Exception:
org.apache.jasper.JasperException: An exception occurred processing JSP page /FinancialAssessment.jsp at line 440
437:
438:
439:
440:
if(std.prev_treatment_start_date.equals("null"))
441: {
442: System.out.println("out by krishna------------");
443:
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
root cause:
java.lang.NullPointerException
org.apache.jsp.FinancialAssessment_jsp._jspService(FinancialAssessment_jsp.java:542)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

If your error line is that one on the if statement which is the most prabably, try this:
if( std == null || std.prev_treatment_start_date == null ) {
.....
This is because in java you have to test each object to avoid a NullPointerException which means that an object is null and cannot have methods or attributes.

Either std or std.prev_treatment_start_date is null. You should use:
if (std == null || std.prev_treatment_start_date == null) {
The way you wrote it means "std.prev_treatment_start_date is a string and has a value, and this value equals the string null".

java code wont run in JSP

I have a JSP page with two tabs and I am trying to run some Java code in the second tab but I keep getting a null pointer exception. I swear my Java Code is correct but the second tab wont show up either.
<%
String fn = request.getParameter("fn9");
String ln = request.getParameter("ln9");
String primaryEmail = request.getParameter("primaryemail9");
CreatingTheProviderFile ctpf = new CreatingTheProviderFile();
char[] c = fn.toCharArray();
if(fn != null){
System.out.println("it is blank");
}else{
System.out.println("it is something else");
}
if(fn != ''){
ctpf.FillNameArray(fn, ln, primaryEmail);
}
%>
JSP for some reason doesnt like the char statement nor does it like the if statement. This is my stacktrace
Dec 18, 2013 11:37:33 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [jsp] in context with path [/TwoWayPortal] threw exception [An exception occurred processing JSP page /patient_discharge.jsp at line 800
797:
798: // CreatingTheProviderFile ctpf = new CreatingTheProviderFile();
799:
800: char[] c = fn.toCharArray();
801:
802: System.out.println(c[0]);
803: // System.out.println(String.valueOf(fn.charAt(0)));
Stacktrace:] with root cause
java.lang.NullPointerException
at org.apache.jsp.patient_005fdischarge_jsp._jspService(patient_005fdischarge_jsp.java:999)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
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:205)
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:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1008)
at
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1852)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
I appreciate any help,
Thank You

The line that throws the NullPointerException is the line with fn.toCharArray(); This implies that fn is null.
Try
if(fn != null){
//do stuff here
}

Yes. fn is null.
// test for null, init to null if fn is null.
char[] c = (fn != null) ? fn.toCharArray() : null;
if (fn != null) {
System.out.println("it is not null");
if (fn.length() > 0) { // fn != '' is illegal, could have used !fn.equals("") -
// note double quotes (not single).
ctpf.FillNameArray(fn, ln, primaryEmail);
}
} else {
System.out.println("it is something else");
}

Before doing fn.toCharArray() check whether fn is null or not. You are checking it later. But if fn is null, you will get exception on fn.toCharArray() only and rest of the code wont execute.

When you change tabs, you may be losing data in request scope (just a guess). As an experiment, you can consider putting data in session scope instead. If it works, you may conider weather or not its of value to leave it as session scope.

Error when trying to search similar images using JSP

I am building a web application for feature extraction and comparing the feature of images, using JSP, Java, and PostgreSQL.
My feature extraction is extracting some features from images, so that then I can compare them (some features are about color, some on the histogram of the image and so. I have special methods that extract them using specific libraries (jars that I add into lib) as you can see in the following example!
Those features are then successfully being added into my PostgreSQL database.
public void GetImageProperties(String targetPath, ImageProperties imagesProperties) throws Exception
{
// load image
FileInputStream imageStream;
imageStream = new FileInputStream(targetPath);
BufferedImage bimg = ImageIO.read(imageStream);
// get properties
imagesProperties.cl = new ColorLayoutImpl(bimg);
imagesProperties.eh = new EdgeHistogramImplementation(bimg);
imagesProperties.sc = new ScalableColorImpl(bimg);
}
Then I add them into a postgresql database(only the features, not the images)
String query = "CREATE TABLE Images (" +
" imageid SERIAL PRIMARY KEY," +
" fname VARCHAR(128)," +
" colorlayout VARCHAR(512), " +
" edgehist VARCHAR(512), " +
" scalablecolor VARCHAR(512) " +
")";
I get this error every time I had loaded an image and want to compare it with all the other images in a directory.
HTTP Status 500 -
type Exception report
message:
description The server encountered an internal error () that prevented it from fulfilling this request.
exception:
org.apache.jasper.JasperException: An exception occurred processing JSP page /query.jsp at line 124
121: if (bSearch) {
122: // get form params
123: query.setTopK(new Integer(request.getParameter("frm_topk")));
124: query.setColorHistogramWeight(new Integer(request.getParameter("frm_weight_c1")));
125: query.setColorDistributionWeight(new Integer(request.getParameter("frm_weight_c2")));
126: query.setTextureWeight(new Integer(request.getParameter("frm_weight_c3")));
127: }
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
root cause:
java.lang.NumberFormatException: For input string: "1.0"
java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
java.lang.Integer.parseInt(Integer.java:492) java.lang.Integer.<init>
(Integer.java:677) org.apache.jsp.query_jsp._jspService(query_jsp.java:256)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.27 logs.

Your problem is here
query.setTopK(new Integer(request.getParameter("frm_topk")));
should be
String parFrm_topk = request.getParameter("frm_topk");
Integer frm_topk = null;
if (parFrm_topk != null && parFrm_topk.length() > 0 && !parFrm_topk.equals("null"))
try {
frm_topk = Integer.valueOf(parFrm_topk);
} catch (NumberFormatException nfe){
throw nfe;
}
if (frm_topk ! = null) {
query.setTopK(frm_topk);
this code is trying to check the parameter that could be empty, why it is empty depends on how flow the app and how parameters are passed through url.