How to set a java compiler in Netbeans
warning: java/lang/Boolean.class(java/lang:Boolean.class): major version 51 is newer than 50, the highest major version supported by this compiler.
It is recommended that the compiler be upgraded.

javac: invalid target release: 1.7
/Applications/NetBeans/NetBeans 7.1.app/Contents/Resources/NetBeans/harness/suite.xml:184: The following error occurred while executing this line:
/Applications/NetBeans/NetBeans 7.1.app/Contents/Resources/NetBeans/harness/common.xml:206: Compile failed; see the compiler error output for details.

<target name="build" depends="-init,branding,release,-hide-excluded-modules" description="Build all modules in the suite.">
    <subant target="netbeans" buildpath="${modules.sorted}" inheritrefs="false" inheritall="false">
        <property name="cluster.path.evaluated" value="${cluster.path.evaluated}"/> <!-- Just for speed of pre-7.0 projects -->
    </subant>
</target>

<nb-javac srcdir="${src.dir}" destdir="${build.classes.dir}" debug="${build.compiler.debug}" debuglevel="${build.compiler.debuglevel}" encoding="UTF-8"
        deprecation="${build.compiler.deprecation}" optimize="${build.compiler.optimize}" source="${javac.source}" target="${javac.target}" includeantruntime="false">
    <classpath refid="cp"/>
    <compilerarg line="${javac.compilerargs}"/>
    <processorpath refid="processor.cp"/>
</nb-javac>

<javac debug="@{debug}" deprecation="${javac.deprecation}" destdir="@{destdir}"
encoding="${source.encoding}" excludes="@{excludes}"
executable="${platform.javac}" fork="${javac.fork}" includeantruntime="false"
includes="@{includes}" source="${javac.source}" srcdir="@{srcdir}"
target="${javac.target}" tempdir="${java.io.tmpdir}">

<javac debug="@{debug}" deprecation="${javac.deprecation}" destdir="@{destdir}"
encoding="${source.encoding}" excludes="@{excludes}"
executable="${platform.javac}" fork="yes" includeantruntime="false"
includes="@{includes}" source="${javac.source}" srcdir="@{srcdir}"
target="${javac.target}" tempdir="${java.io.tmpdir}">