我的 Mac 上安装了多少个 Java 版本？

Question

I'm a bit confused now. When I run the command java --version in the terminal i get: java 13.0.1. When I open the system preferences and click the java app and then about, i see it says Java version 8 1.8.0_231

Does that mean I have 8, 13 or both?

When I check through the java app.

When I check through the terminal.

When i check for all JDK installed on my system (only 1 version pop ups).

Answer 1

You can have multiple JDK installed in one machine but you can have only one version set as default Java SDK. Looks like you have Java 13 set as default.

Try running the following :

echo $JAVA_HOME

You can also go to the tab Java and see the list of all Java Runtime Environments (JRE.)

Please note that just because you have multiple JREs available doesnot mean all corresponding SDK are also there.

Answer 2

You can have many version of java on your Mac. But you can run only one of this in a process. On my Mac, system preferences run with java path :

/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java

But in terminal, this run with java path:

/usr/bin/java

I think you can replace java file in /usr/bin by another version java you want.

Answer 3

that means you jdk version is 13 , and your jre version is 1.8.

jre is used for running java apps ,and the jdk(java development kit) is for building apps with java language. java jdk is like the android sdk