CMSC131 Final Exam Practice Questions Disclaimer The following are questions that try to provide you with some practice material for the final exam By no means do they represent the only material you should know for the final exam We will not be providing answers to this set of questions however feel free to see the instructors or TAs for assistance during office hours Some of the questions can be considered challenging A Miscellaneous 1 What is the Java Virtual Machine 2 What is byte code 3 How can you generate bytecode for a program called Test java 4 What is the difference between a syntax error and a run time error 5 Can every class in Java have a main method 6 Write an output statement that prints the following string the path to use is home games The quotes and backslash must be printed 7 Given the following code Scanner scanner new Scanner System in String name scanner next if name null name length 5 scanner close System out println name a Does it makes a difference if the expression name null appears after name length 5 b Which Java feature associated with the and operators is the above example relying on 8 What is the default value for a local variable 9 What is the default value for an instance variable 10 Rewrite the following cascaded if statement using a switch statement Scanner scanner new Scanner System in int age scanner nextInt System out println rental possible System out println Legal age if age 21 else if age 25 else if age 15 else scanner close System out println Party System out println Unknown 11 Are the numeric comparisons in the following example valid Scanner scanner new Scanner System in int a scanner nextInt b scanner nextInt double c scanner nextDouble d scanner nextDouble if a b if c d System out println Same integers System out println Same doubles 12 Why the following swapWrong method does not swap the values Would it make a difference if instead of int temp x x y y temp integer parameters we were using Integer parameters public static void wrongSwap int x int y public static void main String args int a 10 b 20 wrongSwap a b System out println a b 13 Write pseudocode for a program that determines whether any two consecutive values in a sequence of values differ by at most a particular value For example for the sequence 9 10 18 16 two consecutive values differ by at most two 14 How do the String and StringBuffer classes differ 15 What is the difference between method overloading and method overriding Provide examples 16 Provide an expression using the Random class that generates a random value in the range 4 10 17 What is the difference between final int x and final static int x 18 What is the difference between a shallow copy and a deep copy 19 Which two methods of the Object class do we often override B Classes 1 What is the role the constructor plays in a class 2 What is a copy constructor 3 What is the current object this reference 4 What is the heap 5 What is the difference between a class and an object 6 What is the value stored by a reference variable 7 What is the difference between a static method and a non static method 8 When should you define a method as static 9 Define an interface called Road with the following methods a String getName b double getDistance a Instance variables i number integer ii name String iii distance double b Non static methods 10 Define a class called Highway that has specifications below The class implements the above Road interface i Constructor Takes a number name and distance as parameters ii Default constructor Initializes the object with the values 0 NO NAME and 0 as the values for number name and distance respectively iii get and set methods for all instance variables iv equals method Two roads are considered equal if they have the same number v toString Returns a string with object information number name distance c Static methods i getCount Returns the number of Road objects that have been created d This class implements the Comparable interface Objects will be compared based on the number with highways having a lower number appearing first if we were to sort an ArrayList of them Feel free to add any other variables methods you understand are needed 11 Define a class called Roadtrip with the following specifications a Instance variables i name String ii route ArrayList Road b Static methods i addRoad Static method that has as parameters a Roadtrip object and a Road The Road will be added to the specified Roadtrip object c Non static methods i Constructor Takes a name parameter representing the roadtrip s name ii addRoad Appends a Road object to the ArrayList You must implement this method using the addRoad static method above The method returns a reference to the current object iii removeRoad Removes the road from the ArrayList associated with a particular name iv tripDistance Returns the total distance associated with the roadtrip v equals method Two roadtrips are the same if they have the same name vi toString Returns a string with the roadtrip name followed by information about each road in the route Feel free to add any other variables methods you understand are needed 12 Assume you also have a class named LocalRoad that implements the Road interface Implement the method printInfo that has the following signature void printInfo ArrayList Road roads The method will print the road number of highways that are part of roads ArrayList Remember that not all roads are highways hint use instanceof C Arrays 1 Define a method called rotateLeft that will rotate elements in an integer array by a particular number of positions For example given an array with the values 10 4 5 70 rotating the array by 2 will generate the array 5 70 10 4 2 Define a method called hasThreeOfAKind that returns true if an array of length 5 has three values that are the same and false otherwise 3 Define a method called drawHourClass that draws an hour glass with a specific number of lines For example calling drawHourClass 4 will draw the following diagram 4 Define a method called filter that has the prototype below and that relies on the Highway class you defined above The method returns a new array with copies of Highway objects that have a number in the specified range The will throw an IllegalArgumentException if the list is null or startRange is greater than endRange public static Highway filter Highway list int startRange int endRange 5 Define a method called includesAll that has the prototype below and relies on the above Highway
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