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You can refer below resource for swapping two numbers,
https://www.flowerbrackets.com/java-program-to-swap-two-numbers/

You can refer below resource for difference between equals() and == with some example,

http://www.flowerbrackets.com/string-compare-java-program/

Below is the code,



import java.util.*;

public class JavaPrimeNumber
{
public static void main(String[] args)
{

You can refer the links below. Mentioned links have rich resource with explanation. Hope it helps.

https://docs.oracle.com/javase/tutorial/datetime/iso/datetime.html
...

If you want to change it to file object as an alternative I would suggest to refer link below with an explanation and example

Directory in java.