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a question on Runtime.getRuntime().totalMemory()

 
cake naiyou
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The following function is used to compute memory usage.



I do not understand how to understand "Runtime.getRuntime().totalMemory()"? In specific, how to understand the relationships connecting "Runtime", "getRuntime()" and "totalMemory()"?
 
Rob Spoor
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Runtime is an abstract class. There is no direct way to instantiate it. It has a static method to get an instance of some unknown subclass. This method is called getRuntime(). Therefore, Runtime.getRuntime() returns an instance of a subclass of Runtime.
totalMemory() is an instance method that you call on that instance. Your single line is similar to this:
 
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