[Eric]

Try something like that:

Code:

System.out.println(Runtime.getRuntime().freeMemory());     
long memoryBefore = Runtime.getRuntime().freeMemory();
PDDocument document = PDDocument.load("c:\\01.pdf");
long memoryAfter = Runtime.getRuntime().freeMemory();
System.out.println( (memoryBefore -long memoryAfter));