Get the memory in your Java virtual machine

long totalMemory()

Returns the total amount of memory in the Java virtual machine.

long freeMemory()

Returns the amount of free memory in the Java Virtual Machine.

long maxMemory()

Returns the maximum amount of memory that the Java virtual machine will attempt to use.

public class Main {
  public static void main(String[] args) {
    Runtime runtime = Runtime.getRuntime();
    System.out.println("Total memory:"+runtime.totalMemory());
    System.out.println("Free memory:"+runtime.freeMemory());
    System.out.println("Max memory:"+runtime.maxMemory());
  }
}

The output:

Total memory:5177344
Free memory:4991032
Max memory:66650112

1. Runtime class
2. Get the instance of a runtime
3. Get the memory in your Java virtual machine
4. Shut down hook
5. Get the available processor
6. Exit and halt Java virtual machine
7. Run garbage collector and finalization methods
8. Execuate a system command