what is available in .class file in java and jvm exceptions

To see what is available in a.class file we can take the help of java profiler command.

When we use the java profile command we have observe the following code in Add.class

Ex:

Public class Add extends java.lang.object
{

public Add();

public static void main(java.lang.String[])      //save Add.class

If we want to see all the instructions also we have to use an option “_c”

Ex:

            Javap –c Add

We can invoke the JVM by using the command java. When we invoke the JVM it searches for appropriate class file. It the class file is available it loads the class into JVM’s memory.

• If the class is not available JVM throws and Exception java.lang.Noclass Def FoundError: sub.

 

 

• After the class is loaded JVM checks for main method. If it is available JVM starts the execution from main method.
• If the main method is not available JVM throws an Exception NO such method Found Error: main