I need someone to just write this out the way it is supposed to be so I have an answer key; Thanks. Introduction Java is a strongly typed language, meaning that the compiler and JVM enforce proper matching of the type of data in use. Recall that we cannot even assign a long variable to an int variable without causing a "type mismatch" syntax error. Generics allow us to abstract over data types. The ArrayList class from the java.util package yields a data structure that is an abstract data type (ADT) . Look at its code definition here. We can easily declare an ArrayList of String, Integer, Double, or some other object. This "multipurpose use" is precisely the beauty of a generic class. Without this we would (and have) made separate arrays and methods to hold and manipulate each data type. For your first foray into generics, you will study two simple classes from the interface for the Couple class. This class has two members (thus a "couple"). The members are of type T. Task 1 You will implement a generic version of the Couple class. The following code is an ADT for two String members. To convert this ADT to a generic Couple, you will introduce a type parameter T. This parameter can be thought of as a variable for which one can substitute a (reference) type. You will need to: use the Diamond after the class name replace String with T everywhere else use the member object's toString() method within the Couple.toString() method to access its value. (Recall that every Java object inherits from Object, so a toString() method is available.) class Couple of two Strings: // An ADT for Two strings class Couple { // fields private String first; private String second; // constructor Couple(String f, String s) { first = f; second = s; } // getters and setters String getFirst() { return first; } String getSecond() { return second; void setFirst(String f) { first = f; void setSecond(String s) { second = s; } // override an Object method public String toString() { return "(" + first + ", " + second + ")"; } } Now add one more method to the Couple class. Creating an equals() method requires some thought. We don't want to compare the object references but the members first and second in one object to first and second in the other object. We need a boolean method to which we pass in the object whose member variables should be compared to this object's members. The complication arises when we try to compare our Couple-of-anything ADT to another Couple-of- anything ADT. Our first attempt might be: public boolean equals(Object otherObj){ boolean isEqual = false; Couple o = null; if (otherObj instanceof Couple) { o = (Couple) otherObj; isEqual = (this.first.equals(o.first) && (this.second.equals(o.second)); } } Adding this to Couple.java, we find it does not compile. How very sad. The problem is that the instanceof operator does not work on parameterized types. Instead we can call the getClass() method (ask yourself where this method is defined) on both this and otherObj then compare the } } returned values. (Did you answer that getClass() is inherited from Object? Good job!). So now our next attempt might be: public boolean equals(Object otherObj){ boolean isEqual = false; Couple o = null; if (this.getClass() == otherObj.getClass()) { o = (Couple) otherObj; isEqual = (this.first.equals(o.first) && (this.second.equals(o.second)); } } This survived the compile process, but there is a warning that our program has used an unsafe operation. Eclipse reports, "Type safety: unchecked cast from Object to Couple". The problem is with this line: o = (Couple) otherObj; Even though we will check the class in the if condition, the compiler is not able to prove that a ClassCastException will not be thrown, so it provides a warning. What to do? Nothing for it but to suppress the warning by adding an annotation (a note to the compiler, like we do with @override). @SuppressWarnings("unchecked") public boolean equals(Object otherObj){ boolean isEqual = false; Couple o = null; if (this.getClass() == otherObj.getClass()) { o = (Couple) otherObj; isEqual = (this.first.equals(o.first) && (this.second.equals(o.second)); } } Now you are ready to run the driver class. Yay! Task 2 Load the CoupleClient class that exercises the generic Couple class. Your code will read in data from a file given in the command line. If the file name is not given, the program should terminate after displaying the message: Usage: java CoupleClient inputFileName If the file cannot be opened, the program should terminate after displaying the message: File not found The text file will contain a pair of elements per line. An example of input cc2.txt: sun moon 6.0 12.0 6 12 Your program should be able to use these constructs: Using the generic Couple, a Couple of Strings can be created as follows: Couple cs = new Couple("sun", "moon"); Using the generic Couple, a Couple of Doubles can be created as follows: Couple cd = new Couple(new Double(3.14), new Double(12.34)); But since boxing can occur automatically, this equivalently can be coded as: Couple cd = new Couple(3.14, 12.34); Printing a Couple System.out.println(cs) will output: (sun, moon) After using cs.setSecond("light"), then System.out.println(cs) will output: (sun, light) Your class will be tested with my client driver program. Here is a sample of a test run: > java CoupleClient input.txt (day, night) (6.0, 12.0) (moonlit, night) (6.0, -12.34) ((moonlit, night), (one, Couple)) cs equals cd: false cs equals cs2: false cs equals cs3: false cs equals ccs: false cs equals ccs.first: true cs equals ccs.second: false one moonlit night At this point you should begin to have a feel for structure and syntax of generic types. Task 3 Write a program Prog7a.java that has the following generic methods. 1. Write the following method that returns a new ArrayList. The new list contains the nonduplicate (i.e., distinct) elements from the original list. public static ArrayList removeDuplicates(ArrayList list) 2. Write the following method that shuffles an ArrayList: public static void shuffle(ArrayList list) 3. Write the following method that returns the largest element in an ArrayList: public static > E max(ArrayList list) 4. Write the following main method that tests the above methods. (Use ArrayLists implicit toString() to print. This gives the brackets.) Example runs: [cssc0460@edoras Prog7]$ java Prog7a I 6 7 5 3 1 -1 -2 Program 7, Student Name, cscs0460 Original: [7, 5, 3, 1, -1, -2] Unique: [7, 5, 3, 1, -1, -2] Shuffled: [3, -1, 7, 1, 5, -2] Maximum: 7 output: [cssc0460@edoras Prog7]$ java Prog7a S 4 aba baa bab aab baa Program 7, Student Name, cssc0460 Original: [aba, baa, bab, aab] Unique: [aba, baa, bab, aab] Shuffled: [bab, aab, aba, baa] Maximum: bab Task 4 Write a program Prog7b.java that has the following generic methods.: 1. 2. 3. 4. Implement the following generic method for linear search. public static > int linearSearch(E[] list, E key) Implement the following method that returns the maximum element in an array: public static > E max(E[] list) Implement a generic method that prints the array contents inside brackets and separated by comma and a space. (This mimics the ArrayLists toString() method.) private static void print(E[] list) Write the following main method that tests the above methods. @SuppressWarnings({"unchecked", "rawtypes"}) public static void main(String[] args) { o Read in data type for the array: S for String, D for Double, or I for Integer o Read n number of elements in the array list. o Read in n elements to initialize array list. o Read in k key value to search for in list. o Printlist. o Call linearSearch(list, k) and print the result: o Call max(list) and print the result: Example runs: [cssc0460@edoras Prog7]$ java Prog7b D 4 1.1 -3.14 8.5 0.3 8.5 Program 7, Student Name, cscs0460 [1.1, -3.14, 8.5, 0.3] Key 8.5 was found at position 2 8.5 is the max element [cssc0460@edoras Prog7]$ java Prog7b Program 7, Student Name, cscs0460 [2] Key 3 was not found 2 is the max element