When i try to run a java program (java -javaagent:size.jar ObjectSizeTest
) i get the following error:
Failed to load Premain-Class manifest attribute from D:\workspace\ObjectSizeTest\size.jar
Error occurred during initialization of VM
agent library failed to init: instrument
Here is ObjectSizeTest's code:
public class ObjectSizeTest {
public static void main(String[] args) {
String s = new String("sai");
System.out.println(ObjectSizeFetcher.getObjectSize(s));
}
}
MANIFEST.MF (for size.jar):
Manifest-Version: 1.0
Created-By: 1.5.0_18 (Sun Microsystems Inc.)
Premain-Class: ObjectSizeFetcher
and here is ObjectSizeFetcher's code:
import java.lang.instrument.Instrumentation;
public class ObjectSizeFetcher {
private static Instrumentation instrumentation;
public static void premain(String args, Instrumentation inst) {
instrumentation = inst;
}
public static long getObjectSize(Object o) {
return instrumentation.getObjectSize(o);
}
}
Make sure you have give full java path of the class containing the pre-main method. for example like this org.eclipse.anotherpckg.ObjectSizeFetcher. Secondly there must be a space before the name and carriage return at the end. for example
Manifest-Version: 1.0
Created-By: 1.5.0_18 (Sun Microsystems Inc.)
Premain-Class: org.eclipse.package.ObjectSizeFetcher
The last line is due to carriage return.