Java Questions

Pass By Reference means the passing the address itself rather than passing the value. Passby Value means passing a copy of the value to be passed.

If constructor opens the file 

finalize() method closes that file.

If constructor opens the connection 

finalize() method closes that connection.

To perform finalization operation we must overriding finalize method.

Yes, we can. In order to compile a java program, we don't require any main method. But to execute a java program we must have a main in it (unless it is an applet or servlet). Because main is the starting point of a java program.

Two types of classes:

1) Top Level Class

2) Classes within Class

       i) member classes

             a) static member class

             b) non static member class

      ii) local classes

      iii) anonymous classes

- By using method overriding a sub class can change the definition of super class method.

- By using overriding a sub class can modify the functionality of the super class.

By using super call we can call super class constructors  from sub class constructors and we can initialize super class private data.

boolean isFile();

To do multi threading in java we use interfaces and classes defined in java.lang package.

Those classes and interfaces are:

Java.lang.Runnable, Java.lang. Thread, Java.lang.ThreadGroup