JVM, JRE & JDK


JVM, JRE & JDK

v  Format of class file.
v  Class loading mechanism.

v  Memory Management etc.


JVM




JDK

·                  In Java, classes are packaged and distributed in jar format.
Jar -  Java Archive
·                  Sun Microsystems provides classes of core java library through a jar file named “rt.jar.
·                  C:\NewJava>jar
jar -tf rt.jar

jar -tf rt.jar> a.txt


To compress
jar -crf a.jar *
jar -tf a.jar (to see)

jar -xf a.jar (to extract)





The above program in modified form


PROGRAM first2.java

public class First2
{
public static void main()
{
System.out.println("It is overloaded main.....");
}
public static void main(String args[])
{
System.out.println("Invoked by JRE, invoking overloaded main......");
main();
}
}

OUTPUT –












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