Java has a runtime (the “JRE”, or “Java Runtime Environment”) which is required to run Java applications. There’s also a “JDK” (“Java Development Kit”) which is required to develop applications in Java. There are numerous blogs out there that explain how to install Java from repositories. This blog post will detail how to download and install Oracle’s Java SE manually.<\/p>\n\n\n\n
Oracle Java SE can be downloaded from:<\/p>\n\n\n\n
https:\/\/www.oracle.com\/technetwork\/java\/javase\/downloads\/index.html<\/a><\/p>\n\n\n\n Click on the Download<\/strong> button for the JDK version you wish to install. There are many Linux options available to download, but the rest of this blog post will assume you downloaded the Extract the tar file you downloaded to the directory you wish to install Java in. For example, if you downloaded Java 12 ( Create an environment named Run (source) the above using:<\/p>\n\n\n\n or just:<\/p>\n\n\n\n You could stop there, and Java will work:<\/p>\n\n\n\n You may find yourself in a situation where you need to work on multiple Java projects that use different versions of the JDK. It is possible to quickly switch between different versions of the JDK using update-alternatives.<\/p>\n\n\n\n Register your JDK install with You can view how many “alternatives” for To switch between different versions of <\/code>javac<\/code>:<\/p>\n\n\n\n Don’t forget if you switch your javac version, you should also switch your java version too:<\/p>\n\n\n\n Assuming I want to uninstall JDK 12 which is installed in After this, clean up any files that set Java has a runtime (the “JRE”, or “Java Runtime Environment”) which is required to run Java applications. There’s also a “JDK” (“Java Development Kit”) which is required to develop applications in Java. There are numerous blogs out there that explain how to install Java from repositories. This blog post will detail how to download andRead more about Installing Java on Linux<\/span>[…]<\/a><\/p>\n","protected":false},"author":1,"featured_media":482,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[19,15],"tags":[],"class_list":["post-470","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-coding","category-installation"],"_links":{"self":[{"href":"https:\/\/blog.syddel.uk\/index.php?rest_route=\/wp\/v2\/posts\/470","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.syddel.uk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.syddel.uk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.syddel.uk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.syddel.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=470"}],"version-history":[{"count":11,"href":"https:\/\/blog.syddel.uk\/index.php?rest_route=\/wp\/v2\/posts\/470\/revisions"}],"predecessor-version":[{"id":481,"href":"https:\/\/blog.syddel.uk\/index.php?rest_route=\/wp\/v2\/posts\/470\/revisions\/481"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.syddel.uk\/index.php?rest_route=\/wp\/v2\/media\/482"}],"wp:attachment":[{"href":"https:\/\/blog.syddel.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=470"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.syddel.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=470"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.syddel.uk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=470"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}.tar.gz<\/code> version.<\/p>\n\n\n\nExtract the Oracle Java SE<\/h3>\n\n\n\n
jdk-12_linux-x64_bin.tar.gz<\/code>) and you wish to install Java to \/usr\/local\/lib<\/code>:<\/p>\n\n\n\n[syd:z97] Downloads $ sudo tar -zxvf jdk-12_linux-x64_bin.tar.gz -C \/usr\/local\/lib\/<\/strong>
[sudo] password for syd:
jdk-12\/bin\/jaotc
jdk-12\/bin\/jar
jdk-12\/bin\/jarsigner
jdk-12\/bin\/java
jdk-12\/bin\/javac
...
[syd:z97] Downloads $ ls -l \/usr\/local\/lib\/<\/strong>
total 12
drwxr-xr-x 9 root root 4096 Apr 7 23:32 jdk-12
...
[syd:z97] Downloads $<\/pre>\n\n\n\nSet $JAVA_HOME and update $PATH<\/h3>\n\n\n\n
JAVA_HOME<\/code>, and set it to point to the directory you installed Java to (in this example, \/usr\/local\/lib\/jdk-12<\/code>). Also add the bin directory (i.e. \/usr\/local\/lib\/jdk-12\/bin<\/code>) to your system’s path. I normally make these changes system-wide by creating \/etc\/profile.d\/java.sh<\/code> that contains:<\/p>\n\n\n\nexport JAVA_HOME=\/usr\/local\/lib\/jdk-12
export PATH=$PATH:$JAVA_HOME\/bin
<\/pre>\n\n\n\n$ source \/etc\/profile.d\/java.sh<\/strong><\/pre>\n\n\n\n
$ . \/etc\/profile.d\/java.sh<\/strong><\/pre>\n\n\n\n
$ javac -version<\/strong>
javac 12<\/pre>\n\n\n\nBut wait! There’s more!!!<\/h3>\n\n\n\n
update-alternatives<\/code>:<\/p>\n\n\n\n$ sudo update-alternatives --install \"\/usr\/bin\/java\" \"java\" \"\/usr\/local\/lib\/jdk-12\/bin\/java\" 1<\/strong>
$ sudo update-alternatives --install \"\/usr\/bin\/javac\" \"javac\" \"\/usr\/local\/lib\/jdk-12\/bin\/javac\" 1<\/strong><\/pre>\n\n\n\njavac<\/code> you have using:<\/p>\n\n\n\n$ update-alternatives --list javac<\/strong>
\/usr\/local\/lib\/jdk-12\/bin\/javac
\/usr\/local\/lib\/jdk1.8.0_201\/bin\/javac<\/pre>\n\n\n\n$ sudo update-alternatives --config javac<\/strong>
There are 2 choices for the alternative javac (providing \/usr\/bin\/javac).
Selection Path Priority Status
------------------------------------------------------------------------
0 \/usr\/local\/lib\/jdk-12\/bin\/javac 1 auto mode
1 \/usr\/local\/lib\/jdk-12\/bin\/javac 1 manual mode
2 \/usr\/local\/lib\/jdk1.8.0_201\/bin\/javac 1 manual mode
Press to keep the current choice[*], or type selection number:
<\/pre>\n\n\n\n$ sudo update-alternatives --config java<\/strong>
...
<\/pre>\n\n\n\nUninstalling Java<\/h3>\n\n\n\n
\/usr\/local\/lib\/jdk-12<\/code>:<\/p>\n\n\n\n$ sudo update-alternatives --remove \"javac\" \"\/usr\/local\/lib\/jdk-12\/bin\/javac\"
$ sudo update-alternatives --remove \"java\" \"\/usr\/local\/lib\/jdk-12\/bin\/java\"
$ sudo rm -rf \/usr\/local\/lib\/jdk-12<\/pre>\n\n\n\n$JAVA_HOME<\/code> or add the JDK directory to $PATH<\/code> (in my case, this is done in \/etc\/profile.d\/java.sh<\/code>).<\/p>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"