JAVA

Implement the following two static methods. Note that, although the two methods compute the same function, the first one clears the given NaturalNumber while the second one restores it.

/**

* Returns the product of the digits of {@code n}.

*

* @param n

* {@code NaturalNumber} whose digits to multiply

* @return the product of the digits of {@code n}

* @clears n

* @ensures productOfDigits1 = [product of the digits of n]

*/

private static NaturalNumber productOfDigits1(NaturalNumber n) {...}

/**

* Returns the product of the digits of {@code n}.

*

* @param n

* {@code NaturalNumber} whose digits to multiply

* @return the product of the digits of {@code n}

* @ensures productOfDigits2 = [product of the digits of n]

*/

private static NaturalNumber productOfDigits2(NaturalNumber n) {...}

Implement the static method declared as follows:

/**

* Reports the value of {@code n} as an {@code int}, when {@code n} is

* small enough.

*

* @param n

* the given {@code NaturalNumber}

* @return the value

* @requires n <= Integer.MAX_VALUE

* @ensures toInt = n

*/

private static int toInt(NaturalNumber n) {...}

Implement the static method declared as follows:

/**

* Reports whether the given tag appears in the given {@code XMLTree}.

*

* @param xml

* the {@code XMLTree}

* @param tag

* the tag name

* @return true if the given tag appears in the given {@code XMLTree},

* false otherwise

* @ensures

 
 * findTag =
 
 * [true if the given tag appears in the given {@code XMLTree}, false otherwise]
 
 * 

*/

private static boolean findTag(XMLTree xml, String tag) {...}