05/03/25
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Q)What is autoboxing?
 =>Implicit conversion of primitive type to wrapper type is known as autoboxing.
Q)What is auto-unboxing?
 =>Implicit conversion of wrapper type to primitive type is known as auto-unboxing.

Note:- JDK 1.5 onwards autoboxing  and auto-unboxing feature introduced.

 For eg.
 class AutoBoxingUnboxing{
	static int  x(Integer i){
		 int sum=10+i;//auto-unboxing
		 return sum;
	}
	public static void main(String[] args) {
		int a=40;
		System.out.println(x(a));//autoboxing
	}
}

Q)What is a package in Java?
=>A package is a grouping mechanism in which, related class files are grouped
and made available to other applications or other parts of the same application.

Note:- A package in Java is equivalent to folder/directory in OS's file system.
          =>Always a Java class file(class/interface) should belong to a package.

=>We have two kinds of packages.
             1)user defined packages(Our own project's class files are grouped here)
	     2)built-in packages(library class files are grouped here)
=>Some examples of built-in packages.
          1)java.sql
	  2)java.io
	  3)java.util
	  4)java.lang  etc.

=>A realtime Java project is divided to some partitions(layers).
           For eg.
	              1)data access layer(database communication classes)
		      2)service layer (data processing classes)
Note:- Each layer's java classes are grouped into a user defined package.
            For eg.    com.hdfc.dao
	                  com.hdfc.service
			  com.hdfc.exception
Q)How to create a user defined package in Eclipse IDE?
  =>by using package statement.

  for eg.
package in.ashokit.exception;
public class AccountNotFoundException extends Exception{
}

Q)How to make a class available to a Java application?
=>by using import statement.
For eg.
package in.ashokit.service;
import in.ashokit.exception.AccountNotFoundException;
public class Account{
    public void withdraw() throws AccountNotFoundException{
    }
}
Note:- package statement should be the first non comment statement
in a Java source file.