Get number of memory in Java VM

Every Java application has a single instance of class java.lang.Runtime that allows the application to interface with the environment in which the application is running.

• 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.
• long totalMemory()
  Returns the total amount of memory in the Java virtual machine.

public class testMem {
    
    public static void main(String[] args){
        System.out.println("helloraspberrypi.blogspot.com");
        
        //the total amount of memory in the Java virtual machine
        long totalMem = Runtime.getRuntime().totalMemory();
        //the maximum amount of memory that the Java virtual machine will attempt to use
        long maxMem = Runtime.getRuntime().maxMemory();
        //the amount of free memory in the Java Virtual Machine
        long freeMem = Runtime.getRuntime().freeMemory();
        
        System.out.println("totalMemory() - " + totalMem);
        System.out.println("maxMemory() - " + maxMem);
        System.out.println("freeMemory() - " + freeMem);
        
    }
    
}

We can run java with -Xms and -Xmx options to set Java heap size:

• -Xms<size> set initial Java heap size
• -Xmx<size> set maximum Java heap size

Run on Raspberry Pi: