After acquiring Sun, Oracle further evolved HotSpot by combining important parts of their competing product, JRockit. HotSpot was developed at Sun as a commercial product. Parts of the app are then selected to be fully-compiled as native code and cached, for much faster execution. HotSpot is one implementation of JIT technology that starts by running interpreted, and watches the actual performance of the app. Over the decades, there have been many implementations of the JVM. Or the bytecode can be fully compiled and cached, to run faster than through the interpreter, in a process known as Just-In-Time (JIT) compiling. This can be done on-the-fly by an interpreter. A JVM runs programs compiled to its imaginary instruction set written to storage as an intermediate representation known as bytecode.Īt runtime, the bytecode must be translated from the imaginary instruction set to the actual instruction set of the CPU of the host machine. javapath Īs you see javapath (that is in PATH environment variable) points to javapath_target_3015921.Note: AdoptOpenJDK has changed its name to Adoptium after moving to the Eclipse Foundation in late 2020-06.Ī Java Virtual Machine (JVM) is an imaginary computer that has never been physically built as hardware.
In path C:\Program Files (x86)\Common Files\Oracle\Java: > dir "C:\Program Files (x86)\Common Files\Oracle\Java" On Windows machine, there are also two another differences between JDK 8 and JDK 11.Ī standalone JRE alongside JDK as you can see: > dir /b "C:\Program Files\Java" Same snapshots on Windows machine: > dir /b "C:\Program Files\Java\jdk-11.0.1" Same snapshot about Oracle JDK 8 (See jre folder specially): # ls /usr/java/jdk1.8.0_191-amd64/ĬOPYRIGHT LICENSE THIRDPARTYLICENSEREADME-JAVAFX.txt As you can see there is no jre folder: # ls /usr/java/jdk-11.0.1/īin conf include jmods legal lib README.html release This is a snapshot of installation path on CentOS 7. But I saw an unexpected thing! Where is JRE? _windows-圆4_bin.exe (first on a Linux machine and second on a Windows machine). I downloaded and installed Oracle JDK 11 from its official site. I was expecting JRE to be installed with JDK.ĭo final users of our apps need to install JDK?
But where is JRE 11?!Īlso, JDK 11 doesn't include a JRE. You can find JRE 8, JRE 9 and JRE 10 on Oracle's official website (click on each).
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