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Is there any sizeof-like method in Java?
Does Java have operator something like sizeof() in C?
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user1879118
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6no............. – John Dvorak Dec 28 '12 at 14:53
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1What are you trying to do which would need it? Most memory profilers will tell you how much memory is being used by what. – Peter Lawrey Dec 28 '12 at 14:55
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1See also http://stackoverflow.com/questions/52353/in-java-what-is-the-best-way-to-determine-the-size-of-an-object – Mat Dec 28 '12 at 14:55
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http://www.javaworld.com/javaworld/javaqa/2003-12/02-qa-1226-sizeof.html?page=2 – John Dvorak Dec 28 '12 at 15:01
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If you want to find out if something exists in Java, try searching for `java xxxx`. `java sizeof` gets many hits, including Stackoverflow questions. – Patricia Shanahan Dec 28 '12 at 15:13
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The answer is no.
However there are some simple approaches to achieve that. Write your own sizeof method.
public static int sizeof(Class cl)
{
if (cl == Integer.class || cl == int.class) return 4;
if (cl == Character.class || cl == char.class) return 2;
//...
}
The size of the object will depend on the JVM implementation. There is the Java SizeOf project which handles all cases correctly.
Martijn Courteaux
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1There are _many_ classes, not just those encapsulating primitive data types. – John Dvorak Dec 28 '12 at 14:59
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Actually, you can get the size fairly accurately, see https://github.com/jbellis/jamm, "MemoryMeter is as accurate as java.lang.instrument.Instrumentation.getObjectSize" – sbridges Dec 28 '12 at 15:06