What wrapper class methods convert a number from decimal to another numbering system? What wrapper classes are these methods a member of?
> If a method has a throw statement, does it always have to have a throws clause in its header? Why or why not?
> What is the difference between the throw statement and the throws clause?
> What is the purpose of the argument that is passed to an exception object’s constructor? What happens if you do not pass an argument to the constructor?
> What does the throw statement do?
> When are you required to have a throws clause in a method header?
> What are the differences between a checked and an unchecked exception?
> A program’s main method calls method A, which calls method B. None of these methods performs any exception handling. The code in method B throws an Âexception. Describe what happens.
> What is the call stack? What is a stack trace?
> Convert the following while loop to a for loop: int count = 0; while (count < 50) { System.out.println("count is " + count) ; Count++ ; }
> When does the code in a finally block execute?
> Briefly describe what an exception is.
> If a method in a subclass has the same name as a method in the superclass, but uses a different parameter list, does the subclass method overload or override the Âsuperclass method?
> If a method in a subclass has the same signature as a method in the superclass, does the subclass method overload or override the superclass method?
> How can a subclass method call an overridden superclass method?
> Under what circumstances would a subclass need to override a superclass method?
> Look at the following classes: public class Ground { public Ground() { System.out.println("You are on the ground."); } public Ground(String groundColor) { System.out.println("The ground is " + groundColor); } } public class Sky extends Ground { public S
> Look at the following classes: public class Ground { public Ground() { System.out.println("You are on the ground."); } } public class Sky extends Ground { public Sky() { System.out.println("You are in the sky."); } } What will the following program displ
> Class B extends class A. (Class A is the superclass and class B is the subclass.) Describe the order in which the class’s constructors execute when a class B object is created.
> Write the first line of a class named Employee, which implements interfaces named Payable and Listable.
> Convert the while loop in the following code to a do-while loop: Scanner keyboard = new Scanner(System.in); int x = 1; while (x > 0) { System.out.print("Enter a number:”) ; x = keyboard.nextInt (); }
> Write the first line of a class named Customer, which implements an interface named Relatable.
> If an interface has fields, how are they treated?
> How is an interface different from an abstract class, or any class?
> How is an interface similar to an abstract class?
> What is the purpose of an interface?
> If a class is defined as abstract, what can you not do with the class?
> What is the purpose of an abstract class?
> If a subclass extends a superclass with an abstract method, what must you do in the subclass?
> Look at the following class declarations and answer the questions that follow them: public class Shape { private double area; public void setArea(double a) { area = a; } public double getArea() { return area; } } public class Circle extends Shape { priva
> What is the purpose of an abstract method?
> Write a for loop that calculates the total of the following series of numbers: 130+229+328+⋯301
> Recall the Rectangle and Cube classes discussed earlier, as shown in Figure10-18. 1. Is the following statement legal or illegal? If it is illegal, why? Rectangle r = new Cube(10, 12, 5); 2. If you determined that the statement in part a is legal, are th
> When you create a class, it automatically has a toString method and an equals method. Why?
> Look at the following class definition: public class ClassD extends ClassB { (Member Declarations . . .) } Because ClassD inherits from ClassB, is it true that ClassD does not inherit from the Object class? Why or why not?
> Why is it easy to give package access to a class member by accident?
> What is the difference between private access and package access?
> Why should you avoid making class members protected when possible?
> What is the difference between private members and protected members?
> When a class member is declared as protected, what code may access it?
> How do you prevent a method from being overridden?
> Here is the first line of a class declaration. What is the name of the superclass? What is the name of the subclass? public class Truck extends Vehicle
> Write a for loop that displays the following set of numbers: 0, 10, 20, 30, 40, 50 . . . 1000
> Look at the following declaration: String cafeName = "Broadway Cafe"; String str; Which of the following methods would you use to make str reference the string “Broadwayâ€. startsWith regionMatches substring indexOf
> Modify the method so it performs a case-insensitive test. The method should return true if the argument ends with “ger†in any possible combination of uppercase and lowercase letters.
> Write a method that accepts a reference to a String object as an argument and returns true if the argument ends with the substring “gerâ€. Otherwise, the method should return false.
> Write a loop that counts the number of uppercase characters that appear in the String object str.
> What will the following code display? char var = '$'; System.out.println(Character.toUpperCase(var));
> Write a loop that asks the user, “Do you want to repeat the program or quit? (R/Q)â€. The loop should repeat until the user has entered an R or Q.
> What is the purpose of the MIN_VALUE and MAX_VALUE variables that are members of the numeric wrapper classes?
> What is the output of the following statement? System.out.println(Character.toUpperCase(Character.toLowerCase('A')));
> Write a statement that converts the following integer to a string and stores it in the String object referenced by str: int i = 99;
> Write code that does the following: opens a file named NumberList.txt, uses a loop to write the numbers 1 through 100 to the file, and then closes the file.
> Look at the following string: "dog$cat@bird%squirrel" Write code using the String class’s split method that can be used to extract the following tokens from the string: dog, cat, bird, and squirrel.
> Look at the following string: "/home/rjones/mydata.txt" Write code using the String class’s split method that can be used to extract the following tokens from the string: home , rjones , mydata , and txt.
> Look at the following code: String str = "one two three four"; String[] tokens = str.split(" "); int x = tokens.length; String first = tokens[0]; What value will be stored in x? What value will the first variable reference?
> The following string contains three tokens. What are they? What character is the delimiter? "apples pears bananas"
> How does the StringBuilder class’s replace method differ from the String class’s replace method?
> You wish to change a specific character in a StringBuilder object. What method do you use?
> You wish to delete a specific character from the existing contents of a StringBuilder object. What method do you use?
> You wish to insert a string into the existing contents of a StringBuilder object. What method do you use?
> You wish to add a string to the end of the existing contents of a StringBuilder object. What method do you use?
> Write an if statement that displays the word “digit†if the char variable ch contains a numeric digit. Otherwise, it should display “Not a digit.â€.
> Complete the following program so it displays a random integer in the range of 1 through 10. // Write the necessary import statement(s) here. public class ReviewQuestion15 { public static void main(String[ ] args) { // Write the necessary code here. } }
> Look at the following statement: String city = "Asheville"; Rewrite this statement so that city references a StringBuilder object instead of a String object.
> In a program that makes lots of changes to strings, would it be more efficient to use String objects or StringBuilder objects? Why?
> The String class is immutable. What does this mean?
> Assume that a program has the following declarations: double number = 9.47; String str; Write a statement that assigns a string representation of the number variable to str.
> What will the following code display? String str1 = "William "; String str2 = " the "; String str3 = " Conqueror"; System.out.println(str1.trim() + str2.trim() + str3.trim());
> Look at the following code: String str1 = "To be, or not to be"; String str2 = str1.replace('o', 'u'); System.out.println(str1); System.out.println(str2); You hear a fellow student claim that the code will display the following Tu be ur nut tu be Tu be u
> What is the difference between the getChars and toCharArray methods?
> The + operator, when used with strings, performs the same operation as what String method?
> What is the difference between the getChars and substring methods?
> What is the difference between the indexOf and lastIndexOf methods?
> Write nested loops to draw this pattern:
> Write a statement that converts the contents of the char variable big to lowercase. The converted value should be assigned to the variable little.
> Assume that the following enumerated data type has been declared: enum Letters { Z, Y, X } What will the following code display? if (Letters.Z.compareTo(Letters.X) > 0) System.out.println("Z is greater than X."); else System.out.println("Z is not greater
> Assume that the following enumerated data type has been declared: enum Creatures{ HOBBIT, ELF, DRAGON } What will the following code display? System.out.println(Creatures.HOBBIT + " " + Creatures.ELF + " " + Creatures.DRAGON);
> Look at the following statement, which declares an enumerated data type: enum Flower { ROSE, DAISY, PETUNIA } 1. What is the name of the data type? 2. What is the ordinal value for the enum constant ROSE? For DAISY? For PETUNIA? 3. What is the fully qual
> Look at the following code. Stock stock1 = new Stock("XYZ", 9.65); Stock stock2 = new Stock("SUNW", 7.92); While the equals method is executing as a result of the following statement, what object does this reference? if (stock2.equals(stock1)) System.out
> Describe the limitation of static methods.
> What action is possible with a static method that isn’t possible with an instance method?
> What is the difference between an instance field and a static field?
> Look at the following statements: int[] numbers1 = { 1, 3, 6, 9 }; int[] numbers2 = { 2, 4, 6, 8 }; int result; Write a statement that multiplies element 0 of the numbers1 array by element 3 of the numbers2 array and assigns the result to the result vari
> Write a statement that creates and initializes a double array with the following Âvalues: 1.7, 6.4, 8.9, 3.1, and 9.2. How many elements are in the array?
> Write an input validation loop that asks the user to enter a number in the range of 1 through 4.
> Show how the double variables temp, weight, and age can be declared in one statement.
> What is the output of the following code? int[] values = new int[5]; for (int count = 0; count < 5; count++) values[count] = count + 1; for (int count = 0; count < 5; count++) System.out.println(values[count]);
> What happens in Java when a program tries to use a subscript that is out-of-bounds?
> What does it mean for a subscript to be out-of-bounds?
> What is the difference between an array’s size declarator and a subscript?
> What is the difference between an ArrayList object’s size and its capacity?
> How do you determine an ArrayList object’s size?
> What would the valid subscript values be in a four-element array of doubles?
> How do you insert an item at a specific location in an ArrayList object?
> How do you retrieve a specific item from an ArrayList object?
> How do you remove an item from an ArrayList object?
> Modify the code you wrote in Question 18 so it adds all of the numbers read from the file and displays their total.
> How do you add items to an ArrayList object?
> Write a statement that creates an ArrayList object and assigns its address to a variable named lizards. The ArrayList should be able to store String objects only.
> Write a statement that creates an ArrayList object and assigns its address to a variable named frogs.