Let's look at the details few details of object header and calculate the memory size an object occupies inside JVM Heap. Each Object contains following information. • The Object Header. • The memory for primitive types.
• The memory for reference types.
• Offset / alignment - in fact, these are a few unused bytes that are placed after the data object itself. This is done in order that an address in memory was always a multiple of machine word, to speed up the memory read + reduce the number of bits for a pointer to an object. It is also worth noting that in java a size of any object is multiple of 8 bytes! • Object Header : In case of 32-bit system, the header size is 8 bytes, in the case of 64-bit system, respectively is 16 bytes. It contains following information. 1 Hash Code - 2 Garbage Collection Information - each java object contains the i...
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