Hi i am new to java and here too,
i have one doubt i have one class and i compile it, jvm converts it to byte code, if i run this its fine but if i change something into byte code than complier will give some error,
my doubt is how does complier that given byte code is modified?
if i run this its fine but if i change something into byte code than complier will give some error,
You cannot just change something in the byte code- You got to follow the byte code structure or the guidelines which the compiler uses to generate the byte code.
If you want to play with the byte code at run time you can have a look at- Byte Code instrumentation.
well i just want to know how compiler knows that byte code has been modified,
i have one class file abc.class, i complied and it runs, what i did i just open this file with notepad and i can see some byte codes(eg.####), i copy byte codes and paste and save the file, now as per logic abc.class have only byte codes(eg.######) nothing else(and they already complied), so it should run but its giving errors, my doubt is how complier verify that this modify byte code is not original one?
You cannot edit *.class files with Notepad - *.class files are binary files, and Notepad can only edit text files. When you try to edit a *.class file with Notepad, it will become corrupted and unreadable to the Java compiler and JVM.