File $1$:

$/**$

This class represents pairs of integers.

$*/$

public class Pair

$\{$

private int x;

private int y;

public Pair$()//$ default constructor

$\{$

this.x $=0$;

this.y $=0$;

$\}$

$/**$

Create a Pair object with the given values.

@param x x$-$value for the new Pair object

@param y y$-$value for the new Pair object

$*/$

public Pair$($int x$,$ int y$)$

$\{$

this.x $=$ x;

this.y $=$ y;

$\}$

$/**$

Create a Pair object with the given value

as both its x and y values.

@param v value for both numbers in the new Pair object

$*/$

public Pair$($int v$)$

$\{$

this.x $=$ v;

this.y $=$ v;

$\}$

$/**$

Create a Pair object with the same values

as the given Pair object.

@param p Pair object whose values should be copied

$*/$

public Pair$($Pair p$)$

$\{$

this.x $=$ p$.$x;

this.y $=$ p$.$y;

$\}$

$/**$

Get the x$-$value of this Pair object.

@return this Pair's x$-$value

$*/$

public int getX$()$

$\{$

return this.x;

$\}$

$/**$

Change this Pair object to have the given x$-$value.

@param x new x$-$value for this Pair object

$*/$

public void setX$($int x$)$

$\{$

this.x;

$\}$

$/**$

Change this Pair object to have the same x$-$value

as the given Pair.

@param p Pair object whose x$-$value should be copied

$*/$

public void setX$($Pair p$)$

$\{$

this.x $=$ p$.$x;

this.y $=$ p$.$y;

$\}$

$/**$

Get the y$-$value of this Pair object.

@return this Pair's y$-$value

$*/$

public int getY$()$

$\{$

get this.y;

$\}$

$/**$

Change this Pair object to have the given y$-$value.

@param y new y$-$value for this Pair object

$*/$

public void setY$($int y$)$

$\{$

this.y;

$\}$

$/**$

Change this Pair object to have the same y$-$value

as the given Pair.

@param p Pair object whose y$-$value should be copied

$*/$

public void setY$($Pair p$)$

$\{$

$/$

$\}$

$/**$

Change this Pair object to have the same x$-$value

and y$-$value as the given Pair.

@param p Pair object whose x$-$value and y$-$value should be copied

$*/$

public void set$($Pair p$)$

$\{$

$//$ implementation

$\}$

$/**$

Create a new Pair object that contains the swapped x$-$value

and y$-$value from this Pair object.

@return a new Pair that has the swapped values from this Pair

$*/$

public Pair swap$()$

$\{$

return new Pair$($this$.$y$,$ this.x$)$;

$\}$

$/**$

Determine if this Pair object has the same x$-$value

and the same y$-$value as the given Pair.

@param p a reference to a second Pair object

@return true if the given Pair is equal to this Pair

$*/$

public boolean equals$($Pair p$)$

$\{$

return this.x $==$ p$.$x && this.y $==$ p$.$y;

$\}$

$/**$

Determine if the two numbers in this Pair object are the

same two numbers that are in the given Pair without

regard for the order of the numbers. So $(2,3)$ and $(3,2)$

would have "equal numbers".

@param p a reference to a second Pair object

@return true if this Pair and the other Pair contain the same two numbers

$*/$

public boolean equalNumbers$($Pair p$)$

$\{$

$//$ implementation, not sure what to do

$\}$

public String toString$()$

$\{$

return "Pair: $("+$ x $+","+$ y $+")"$;

$\}$

$\}$

File $2$:

import java.util.Scanner;

public class Tester

$\{$

public static void main$($String$[]$ args$)$

$\{$

final Scanner in $=$ new Scanner$($System$.$in$)$;

final int testCase $=$ in$.$nextInt$()$;

if $(1==$ testCase$)$

$\{$

Pair p$1=$ new Pair$()$;

p$1.$setX$(4)$;

p$1.$setY$(-4)$;

System.out.println$($ p$1)$;

Pair p$2=$ new Pair$(-5,5)$;

System.out.println$($ p$2)$;

Pair p$3=$ new Pair$($p$2)$;

System.out.println$($ p$3)$;

Pair p$4=$ p$3.$swap$()$;

System.out.println$($ p$3)$;

System.out.println$($ p$4)$;

p$1.$set$($p$4)$;

System.out.println$($ p$1)$;

$\}$

else if $(2==$ testCase$)$

$\{$

Pair p$1=$ new Pair$(2,3)$;

Pair p$2=$ new Pair$(3,2)$;

System.out.println$($ p$1.$equals$($p$2))$;

System.out.println$($ p$1.$equalNumbers$($p$2))$;

System.out.println$($ p$2.$equalNumbers$($p$1))$;

System.out.println$($ p$1.$equals$($p$2.$swap$()))$;

Pair p$3=$ new Pair$(8)$;

System.out.println$($ p$3)$;

p$3.$setY$(9)$;

System.out.println$($ p$3)$;

p$3.$setX$(7)$;

System.out.println$($ p$3)$;

Pair p$4=$ new Pair$($p$1.$getX$(),$ p$2.$getY$())$;

System.out.println$($ p$4)$;

$\}$

else if $(3==$ testCase$)$

$\{$

Pair p$1=$ new Pair$(4,5)$;

Pair p$2=$ new Pair$(24,25)$;

System