First, what is JDK, JRE, JVM
1, JDK (J ava D evelopment K it Java Development Kit
JDK is available to Java developers, which contains the java development tools (the time required to write java program), also includes a JRE (required when running java program). So install the JDK, you do not have a separate installation of the JRE.
Which development tools: compiler tools (javac.exe) Packaging Tool (jar and so on.)
2, JRE (J ava R untime E nvironment Java Runtime Environment)
Including the Java Virtual Machine (JVM J ava V irtual M achine) required core class libraries and Java programs, if you want to develop a good run Java programs, the computer can only need to install the JRE.
3, Java Virtual Machine (Java Virtal Machine)
The JVM is a virtual computer , having a set of instructions and using the different storage areas. Responsible for implementing refers to
orders, data management, memory, registers.
Features:
- For different platforms, different virtual machines.
- Only a platform provides a virtual machine corresponding java, java procedures can run on this platform
- Java Virtual Machine shielding mechanisms underlying the differences in operation of the platform to achieve a "once, run everywhere
Two, JDK, JRE, JVM relations
JDK = JRE + development tools (e.g., tools compile Javac)
the JRE the JVM + = the Java standard library SE