Notes for this lab

1.  Use the technique discussed in class (using the Scanner class) to prompt the user for input.*

2.  When printing output, use the System.out.println() method.

Requirements

Prompt the user to enter 2 separate strings. Name the strings FirstString and SecondString.

1.  When prompted, enter

      A roach is shorter than a mouse for FirstString

      A Chicken is a dumb animal for SecondString.

2.  Print the two strings, appropriately labeled.

3.  Convert FirstString to upper case and print the result, appropriately labeled.

4.  Find and print, appropriately labeled, the index of the first occurrence of the character c in FirstString.

Exercise 3

1.  Prompt the user to enter a sentence that states the user's name (My name is George, for example).

2.  Prompt the user to enter a character shift from 1 to 4.

3.  Print the sentence and the amount of the shift, appropriately labeled.

4.  Encrypt the sentence using Caesar's shift.

5.  Print the encrypted sentence, appropriately labeled.

6.  Recover and print the original sentence, appropriately labeled.

Exercise 4 (Optional)

Exercise 5: Roman Numerals

Assignment:

1.   Create a class with two public static methods. 

      One will receive an int number and return a String with that int converted into Roman Numerals. 

      The other method will receive a String of Roman Numerals and return the int value of the Roman Numerals.

2. These two methods are static because there is no reason to create an object just to run these calculations.

3. Think of using helper methods to reuse algorithms needed to solve these problems.

4. Assume that your client gives you valid Roman Numerals and the Arabic numbers are positive and less than 4000.

Instructions:

Roman Numerals work differently than our normal Arabic number system.  Roman Numerals have symbols, all in capital letters (and sometimes in lower case), which represent Arabic numbers.  Roman Numerals have been used for identifying movie sequels (i.e., The Godfather: Part II), for publication copyright dates, for numbering monarchs such as Queen Elizabeth II, and for numbering Super Bowls.  See the following table for the Roman Numerals symbols up to 1000.

Usually, numbers are formed by stringing the Roman numerals together and adding them up to make the required number (i.e., II = 2, or XII = 12). If smaller numbers follow larger numbers, the numbers are added (i.e., VIII = 5 + 3 or 8), but if a smaller number precedes a larger number, the smaller number is subtracted from the larger number (i.e., IX = 10 - 1 or 9).

There is shorthand for the case when there are four of the same symbols in a row.  Instead of IIII for 4, it is written as IV or 5 - 1 = 4.  This only applies to symbols that represent powers of ten.  Since our numbers will be less than 4000, this only makes sense for I, X and C.  Some people think this means you can write IC for 99 but that is not going to be allowed.  When using this shortcut, a symbol can only precede a symbol whose value is 5 or 10 times its own value. 

For example, X (10) can only precede L (50) or C (100).  So XL (40) is acceptable, but XD (490?) is not.

Exercise 6

Fill in the Blanks

1. Strings are objects of the ________________________ class.

2. The operator used for concatenation of strings is ___________________________

3. If a reference to an object is no longer needed then the memory it used is reclaimed by the Java ______________________________

4. A reference variable set to ___________________ means that it does not refer to an object.

5. A String is a _______________ data type and a char is a __________________ data type

6. The ________________ operator will check the address of where the object is being stored.

Write Code

1.  Given 2 strings stringOne and stringTwo that have been initialized with 1 sentence

     each.

     a.  Write code that will determine if stringOne comes before stringTwo alphabetically.

         If so, then an appropriate message will be printed. Alternatively, if they are equal

         or if stringOne comes after stringTwo, then an appropriate message will be

         printed.

b.  Write code that will print the substring of stringTwo beginning at index 1 and ending

     at index 3.

Multiple Choice

Circle the correct answer

1.  Which of the following statements is not true?

      A. Every object has an equals method.

      B. If a programmer does not write an equals method for a new class, the default method will  return true if and only if all fields of the two instances of the class contain the same

          values.

     C. The equals method for Strings returns true if and only if the two Strihngs contain the same sequence of characters.

     D. The equals method for arrays returns true if and only if the two arrays point to the same chunk of memory.

     E. The equals method for Strings will return false if one String is shorter than the other.

2.  Assume that the type of variable strList is ArrayList<String>. Consider the following two code segments, both of which are intended to add an exclamation point to the end of

      each string in  the list.

    Which of the following statements about these two code segments is true?

    A.  Both will work as intended, and they will be equally efficient.

    B.  Both will work as intended; Segment 1 will be more efficient  than Segment 2.

    C.  Both will work as intended; Segment 2 will be more efficient than segment 1.   

    D.  Only Segment 1 will work as intended.

    E.  Only Segment 2 will work as intended.

3.  Assume the following declarations have been made.

private String s;

private int n;

public void changer(String x, int y)

{

    x = x +  "peace";

    y = y*2;

}

Assume s has the value "world" and n is 6. What are the values of s and n after the call changer(s, n) ?