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I am trying out a tool jhat here to test my java memory usage. It reads in a heap dump file and prints out information as html. However, the tables shows as follows:
Class Instance Count Total Size class [B 36585 49323821 class [Lcom.sun.mail.imap.IMAPMessage; 790 16254336 class [C 124512 12832896 class [I 23080 11923504 class [Ljava.lang.Object; 13614 6664528 class java.lang.String 108982 2179640 class java.lang.Integer 219502 878008 What are those [B [C etc classes?
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A class — in the context of Java — is a template used to create objects and to define object data types and methods. Classes are categories, and objects are items within each category. All class objects should have the basic class properties.
Instances of the class Class represent classes and interfaces in a running Java application. An enum is a kind of class and an annotation is a kind of interface. Every array also belongs to a class that is reflected as a Class object that is shared by all arrays with the same element type and number of dimensions.
Those are arrays of primitives ([B == byte[], [C == char, [I == int). [Lx; is an array of class type x.
For a full list:
[Z = boolean [B = byte [S = short [I = int [J = long [F = float [D = double [C = char [L = any non-primitives(Object) Also see the Javadoc for Class.getName.
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Looks like an array of characters (C)/bytes (B)/ints (I).
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