Java compiler level does not match

Question

i am using jsf2 hibernate 4.1.4, spring 3.1 and maven 3 in eclipse helios. but i have this error when i try to add dependecy in to POM.

Java compiler level does not match the version of the installed Java project facet.

what does it mean? how can i solve this error?

also i have this warning:

Build path specifies execution environment J2SE-1.5. There are no JREs installed in the workspace that are strictly compatible with this environment.   

my POM:

<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.integrate</groupId>
  <artifactId>integrate</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>integrate</name>
  <dependencyManagement>
    <dependencies>
    </dependencies>
  </dependencyManagement>
  <properties>
  <spring.version>3.1.0.RELEASE</spring.version>
 </properties>

 <dependencies>

  <!-- Spring 3 dependencies -->
  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-core</artifactId>
   <version>${spring.version}</version>
  </dependency>

  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-context</artifactId>
   <version>${spring.version}</version>
  </dependency> 

  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-web</artifactId>
   <version>${spring.version}</version>
  </dependency>

  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-tx</artifactId>
   <version>${spring.version}</version>
  </dependency>

  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-orm</artifactId>
   <version>${spring.version}</version>
  </dependency>

  <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
        </dependency>

  <!-- JSF dependencies -->
  <dependency>
    <groupId>com.sun.faces</groupId>
    <artifactId>jsf-api</artifactId>
    <version>2.1.6</version>
  </dependency>

  <dependency>
    <groupId>com.sun.faces</groupId>
    <artifactId>jsf-impl</artifactId>
    <version>2.1.6</version>
  </dependency>

  <dependency>
   <groupId>javax.servlet</groupId>
   <artifactId>jstl</artifactId>
   <version>1.2</version>
  </dependency>


  <!-- Hibernate dependencies -->
  <dependency>
   <groupId>org.hibernate</groupId>
   <artifactId>hibernate-core</artifactId>
   <version>4.1.4.Final</version>
  </dependency>

  <dependency>
   <groupId>javassist</groupId>
   <artifactId>javassist</artifactId>
   <version>3.12.1.GA</version>
  </dependency>

  <!-- oracle Connector dependency -->
  <dependency>
    <groupId>com.oracle</groupId>
    <artifactId>ojdbc6</artifactId>
    <version>11.2.0.3</version>
</dependency>
<!-- c3p0 dependency -->
      <dependency>
       <groupId>c3p0</groupId>
       <artifactId>c3p0</artifactId>
       <version>0.9.1.2</version>
  </dependency>  


 </dependencies>

the pic:

Answer 1

Just add the build section with the maven-compiler-plugin to your pom.xml.

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>2.3.2</version>
            <configuration>
                <source>1.6</source>
                <target>1.6</target>
                <encoding>UTF-8</encoding>
            </configuration>
        </plugin>
    </plugins>
</build>

Then you should configure project's build path.

Or you can just delete the project from eclipse workspace (without deleting from file system), remove eclipse's settings (.project, .classpath and .settings files and folders) from the project and re-import your project as an existent Maven project to your IDE. Eclipse will re-generate its settings properly.