Java Runtime class
Java Runtime class is used to interact with java runtime environment. Java Runtime class provides methods to execute a process, invoke GC, get total and free memory etc. There is only one instance of java.lang.Runtime class is available for one java application.
The Runtime.getRuntime() method returns the singleton instance of Runtime class.
Important methods of Java Runtime class
Java Runtime exec() method
How to shutdown system in Java
You can use shutdown -s command to shutdown system. For windows OS, you need to provide full path of shutdown command e.g. c:\\Windows\\System32\\shutdown.
Here you can use -s switch to shutdown system, -r switch to restart system and -t switch to specify time delay.
How to shutdown windows system in Java
How to restart system in Java
Java Runtime availableProcessors()
Java Runtime freeMemory() and totalMemory() method
In the given program, after creating 10000 instance, free memory will be less than the previous free memory. But after gc() call, you will get more free memory.
Total Memory: 100139008 Free Memory: 99474824 After creating 10000 instance, Free Memory: 99310552 After gc(), Free Memory: 100182832