Frank Serkland

After discussing this with a colleague, it seems I was trying to mix Spring MVC and Spring Boot, which is problematic.  I'm familiar with Spring MVC, but not Spring Boot.

I added the @ResponseBody annotation to both the welcome and getEmployees methods.  Both methods return what they're supposed to when I run them in the Postman extension of Google Chrome, but I am now just getting "welcome" in the browser screen again, not the actual content.

Frank Serkland wrote:I just tried that and got this exception trace.

I also got this in the browser screen.

Whitelabel Error Page This application has no explicit mapping for /error, so you are seeing this as a fallback. Mon Feb 04 14:35:10 PST 2019 There was an unexpected error (type=Internal Server Error, status=500). Circular view path [welcome]: would dispatch back to the current handler URL [/welcome] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)

Rob Spoor wrote:Frank, did you happen to annotate the class with @RestController? Because @RestController implies not just @Controller, but also @ResponseBody. This means that the "welcome" will not be treated as the name of the JSP file to render, but as the response body.

I just tried that and got this exception trace.
2019-02-04 14:35:10.607 ERROR 9276 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Circular view path [welcome]: would dispatch back to the current handler URL [/welcome] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)] with root cause javax.servlet.ServletException: Circular view path [welcome]: would dispatch back to the current handler URL [/welcome] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)        at org.springframework.web.servlet.view.InternalResourceView.prepareForRendering(InternalResourceView.java:209) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:147) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:315) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1325) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1069) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) ~[spring-webmvc-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.34.jar:8.5.34]        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.9.RELEASE.jar:5.0.9.RELEASE]        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493) [tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800) [tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806) [tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498) [tomcat-embed-core-8.5.34.jar:8.5.34]        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.34.jar:8.5.34]        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167) [na:na]        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641) [na:na]        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.34.jar:8.5.34]        at java.base/java.lang.Thread.run(Thread.java:844) [na:na]

Bear Bibeault wrote:A quick web search reveals that you might just be missing a "/" inreturn "/welcome";

I just tried this, but it didn't work.

Bear Bibeault wrote:I know diddly about Spring or Spring Boot, but it's pretty clear that you've mapped the URI /welcome to a method that returns the string "welcome". There's nothing there that would cause the request to hook up with your JSP that I can see.

In other Spring web applications I've worked on, I've returned a String and the container took me to the JSP with that name.  In this case, my JSP is actually called welcome.jsp, but all I'm getting is the string welcome, not the JSP with the actual content.

I hope I'm putting this in the right folder.  I have a JSP that is not rendering correctly in Spring Boot.  All I get is the word welcome when I call the page, not the actual content.  For what it's worth, I'm retrieving data in a MongoDB database and trying to display it in the JSP.  I have verified that the data is present in the database.  I've tried multiple Google searches to try and find an answer to this.

Here is my controller code.
@RequestMapping("/welcome") public String welcome(Model model) { model.addAttribute("employees", getEmployees()); return "welcome"; } @RequestMapping(value = "/getEmployees", method = RequestMethod.GET) public List<Employee> getEmployees() { MongoDatabase db = getDatabase(); MongoCollection<Document> collection = db.getCollection(COLLECTION); Document query = new Document(); List<Employee> employees = collection.find(query, Employee.class).into(new ArrayList<Employee>()); return employees; }

Here is my JSP code.
<!DOCTYPE html> <%@ taglib prefix="spring" uri="http://www.springframework.org/tags"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> <html> <head> <title>Frank's App</title> <style> table, th, td { border: 1px solid black; } </style> </head> <body> <h2>Frank's App</h2> <div> <table> <tr> <th>First Name</th> <th>Last Name</th> <th>Employee Number</th> <th>Pay Rate</th> </tr> <c:forEach var="employee" items="${employees}"> <tr> <td>${employee.firstName}</td> <td>${employee.lastName}</td> <td>${employee.empNumber}</td> <td>${employee.payRate}</td> </tr> </c:forEach> </table> </div> </body> </html>

Here is my pom.xml.
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>Employee</groupId> <artifactId>Employee</artifactId> <version>0.0.1-SNAPSHOT</version> <name>Employee</name> <description>Employee</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.5.RELEASE</version> </parent> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-tomcat</artifactId> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jstl</artifactId> <scope>provided</scope> </dependency> <dependency> <groupId>org.apache.tomcat.embed</groupId> <artifactId>tomcat-embed-jasper</artifactId> </dependency> <dependency> <groupId>org.eclipse.jdt.core.compiler</groupId> <artifactId>ecj</artifactId> <version>4.6.1</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.mongodb</groupId> <artifactId>mongo-java-driver</artifactId> <version>3.9.1</version><!--$NO-MVN-MAN-VER$--> </dependency> </dependencies> <properties> <java.version>1.8</java.version> </properties> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>

Here is my application.properties.  Please note that the JSP is located directly under /WEB-INF/.
spring.mvc.view.prefix=/WEB-INF/ spring.mvc.view.suffix=.jsp spring.data.mongodb.host=localhost spring.data.mongodb.port=27017 spring.data.mongodb.database=employeeDB

Adding this as the first line in the for loop cured the problem.

digits[i] = new Digit();

I hope I'm putting this question in the right folder. I have an array of objects, and I have defined a setter for a variable in the object. When I call the setter, I get a NullPointerException. Here is the relevant code for the object.

public class Digit extends Thread { private int digit; public void setDigit(int digit) { this.digit = digit; } // run method follows }

Here is the portion of the main class where I define an array and then call the setter.
Digit[] digits = new Digit[10]; for (int i = 0; i < digits.length; i++) { digits[i].setDigit(i); // NullPointerException occurs here }

I was given the following code the other day during an interview.

public class A { int i = 5; public void print() { System.out.println(i); } } public class B extends A { int i = 10; } public class Test { public static void main(String[] args) { A a = new B(); System.out.println(a.i); a.print(); } }

The interviewer asked me what the output would be. I said that in both cases it would be 10. She said no, in the first case it would be 5. She told me something about dynamic binding. I just ran this code and I got 5 in both cases, not just the first. I am confused. If A is an instance of B and i is defined in B to be 10, why do I get 5 in both cases?

I've got a different problem now, so don't bother with this thread.

I am getting the following error:

java.lang.NumberFormatException: For input string: "approved"

The problem is that the approved column is a boolean in my database, or so I believe. Here is how I have it defined.

+----------+---------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------+---------------+------+-----+---------+----------------+ | approved | tinyint(4) | YES | | NULL | | +----------+---------------+------+-----+---------+----------------+

This is the line in my code where I'm defining the call to the database.

Query myQuery = session.createSQLQuery("select * from bulletins where approved = true");

Here is how I have it defined in my model class.

@Column(name="approved") private boolean approved;

I've tried printing out the list in my controller class, and I get the following error.

[Ljava.lang.Object; cannot be cast to com.model.Bulletin

I have resolved the problem. I was missing the right curly brace. The corrected code now looks like this.

<c:set var="comment" value="${fn:split(comment, '\\\\n')}" />

I just tried it with one backslash (\n), and I still got the same error message.

I am trying to split a string on the new line character (\n) in a JSP, but I am getting an error message. Here is my code.

<c:set var="comment" value="${bulletin.note}" /> <c:set var="comment" value="${fn:split(comment, '\\\\n')" />

Here is my error message.

org.apache.jasper.JasperException: /WEB-INF/jsp/BulletinApproval.jsp (line: 33, column: 3) "${fn:split(comment, '\\n')" contains invalid expression(s): javax.el.ELException: Failed to parse the expression [${fn:split(comment, '\\n')] org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:42) org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:443) org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:199) org.apache.jasper.compiler.Validator$ValidateVisitor.checkXmlAttributes(Validator.java:1224) org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:876) org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1538) org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2375) org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2427) org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:895) org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1538) org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2375) org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2427) org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:895) org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1538) org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2375) org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2427) org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2433) org.apache.jasper.compiler.Node$Root.accept(Node.java:474) org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2375) org.apache.jasper.compiler.Validator.validateExDirectives(Validator.java:1817) org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:217) org.apache.jasper.compiler.Compiler.compile(Compiler.java:373) org.apache.jasper.compiler.Compiler.compile(Compiler.java:353) org.apache.jasper.compiler.Compiler.compile(Compiler.java:340) org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:657) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:357) 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:727) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238) org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:262) org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1265) org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1016) org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:965) org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:859) org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:883) org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:781) javax.servlet.http.HttpServlet.service(HttpServlet.java:620) javax.servlet.http.HttpServlet.service(HttpServlet.java:727) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)