I have this small project...
In file src/main/java/com/mycompany/mavenproject2/Root.java:
package com.mycompany.mavenproject2;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.function.Supplier;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/")
public class Root extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request,
HttpServletResponse response)
throws IOException {
Supplier<String> welcomeMsg = () -> "Hello world! I'm a lambda.";
PrintWriter writer = response.getWriter();
writer.println(welcomeMsg.get());
}
}
In file src/main/java/com/mycompany/mavenproject2/HelloBackingBean.java:
package com.mycompany.mavenproject2;
import java.util.function.Supplier;
import javax.faces.bean.ManagedBean;
@ManagedBean
public class HelloBackingBean {
public String getMessage() {
if (false) {
Supplier<String> msg = () -> "Hello from a lambda";
return msg.get();
} else {
return "Hello from string literal";
}
}
}
In file src/main/webapp/hello.xhtml:
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:ui="http://xmlns.jcp.org/jsf/facelets"
xmlns:f="http://xmlns.jcp.org/jsf/core"
xmlns:c="http://xmlns.jcp.org/jsp/jstl/core">
<h:head>
<title>Test Page</title>
</h:head>
<h:body>
<p>#{helloBackingBean.message}</p>
</h:body>
</html>
In pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<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>com.mycompany</groupId>
<artifactId>mavenproject2</artifactId>
<version>0.1</version>
<packaging>war</packaging>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-api</artifactId>
<version>7.0</version>
<scope>provided</scope>
</dependency>
<!-- JSF implementation -->
<dependency>
<groupId>org.apache.myfaces.core</groupId>
<artifactId>myfaces-impl</artifactId>
<version>2.2.5</version>
<scope>runtime</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>9.2.5.v20141112</version>
<configuration>
<scanIntervalSeconds>1</scanIntervalSeconds>
</configuration>
</plugin>
</plugins>
</build>
</project>
Run the site using mvn jetty:run. I am using Maven version 3.2.1.
The problem
If I have the boolean literal in HelloBackingBean be true, nothing shows up when I visit localhost:8080/faces/hello.xhtml. However, if I change it to false (as it is given above), I see "Hello from string literal," as expected.
This leads me to conclude that somehow the very presence of a lambda is causing MyFaces/JSF to misbehave. This is further corroborated by localhost:8080/, which is powered by the Root class, which uses a lambda to get its message and works as expected.
My question is: why is my lambda usage not working in this project? Furthermore, why do I not get some kind of error message? Am I not checking the right places? I see no activity in the terminal when I access localhost:8080/faces/hello.xhtml.
Also worth noting that I assume javac will completely leave out code inside an if (false) block. If it doesn't... well... then I have even less idea how this is working or what's going wrong...
