989708
| Frage | Antworten |
| The type of errors that the compiler will NOT detect are known as: | Semantic errors |
| The method ____ of an Iterator<E> object returns an object of type E from the container that has not yet been accessed by this iterator instance. | next( ) |
| Some of the commonly used public methods of an Iterator object are: | hasNext() and next() and remove() |
| If the expression, pet1.setName("Socrates"), is a valid method call, which of the following MUST be true about the setName() method? | It takes one parameter, a String variable. |
| What do you call a section of code that is written in a natural language (like English), which is ignored by the compiler and is intended for people to read? | Comments |
| A variable that is declared as "final" is known as a ___. | constant |
| What is the purpose of a mutator method? | To change the state of an object. |
| Altering the flow of a program by making a choice is called a(n) ________ statement. | conditional |
| “Coupling” refers to | Logical linkage between separate units of a program that interfere with reusability |
| The BlueJ tool called a/an _____ is used to view the current value (state) of an objects fields. | debugger |
| The signature of a method consists of... | the type of its parameters, name of the method, the number of its parameters |
| A collection of objects and defined states to setup scenarios for several test are know as: | Test Fixtures |
| Given the string declarations below, what is the value of s3 == s2? String s1 = new String("foo"); String s2 = new String("foo"); String s3 = s2; | true |
| What are two key components of Java objects? | Java objects have fields and methods. |
| A Java "HashMap" container is best described as: | A container where elements in the container are accessed via an unique value that has been associated with a data element. |
| Say that a particular item of data is NOT a primitive data type. What must it be? | An object. |
| If the initial condition of any "while" loop is false it will still execute once. | False |
| Examine the following code: int[] numList = new int[4]; int accumulator = 0 for( int index = 0; index < 4; index++) { accumulator = accumulator + index; numList[index] = accumulator; } What will be the value stored in numList[3] after the for loop completes? | 6 |
| What type of instruction uses the equal sign (=) symbol? | Assignment |
| “Cohesion” refers to | The number and diversity of tasks that a program unit implements |
| The part of a method definition that serves as a place holder for data passed to the method is known as | a parameter |
| String variables are primitive variable types. | false |
| Examine the following code: int count = 1; while ( ___________ ) { System.out.print( count + " " ); count = count + 1; } System.out.println( ); What condition should be used so that the code writes out: 1 2 3 4 5 6 7 8 | count < 9 |
| What is a class? | A class is a description and definition of the type of an object. |
| Loop indentation is important because | it makes the loop structure more readable. |
| Another word for "looping" is: | iteration |
| To guard against infinite loops you must insure that _____ | the loop variable is updated in each pass of the loop. |
| What method has the same name as the class name, and is used to perform the initial setup operations for class instance variables? | Constructor |
| What is another name for creating an object? | instantiation |
| Copy of Given the string declarations below, what is the value of s1 == s2? String s1 = new String("foo"); String s2 = new String("foo"); String s3 = s2; | false |
| Which of the following is true of a constructor method? | If a class contains no constructor declarations, Java will automatically supply a default constructor, A constructor is one way to initialize an object's instance variables, A constructor method cannot have a return type. |
| The type of errors that the compiler will detect are known as | Syntax errors |
| Say that there are four classes: Book, Magazine, Newpaper, Publication. What are the likely relationships between these classes? | Publication is the superclass, Book, Magazine, and Newspaper are subclasses of Publication. |
| Does a superclass inherit both member variables and methods? | No - neither can be inherited by the superclass. |
| Which of the following pertains to polymorphic variables? | When a program uses several different types of objects, each with its own variable. |
| What restriction is the on using the super( ) call in a constructor? | It must be used in the first statement of the constructor. |
| Which of the following is an advantage to using inheritance? | Code that is shared between classes needs to be written only once. |
| How can you tell when information is being passed to the constructor of the parent class? | The parameter, either actual or passed into the child class, is passed through the super() call in the constructor of the child class. |
| If you have two classes, Hamster and Animal, where Hamster is a subclass of Animal, what is the correct class header for Hamster? | class Hamster extends Animal |
| Can an object be a subclass of another object? | No—inheritance is only between classes. |
| Does a subclass inherit both member variables and methods? | Yes - Both are inherited |
| Which of the following is NOT an advantage to using inheritance? | One big superclass can be used instead of many little classes. |
| How can you tell when a constructor is being called in a program? | The keyword new is present |
| Which of the following is one form of polymorphism in Java? | When a class has several methods with the same name but different parameter types. |
| What is an advantage of polymorphism? | The same program logic can be used with one objects of several related types. |
| When a class implements an interface, what must it do? | It must declare identical signatures and provide a method body for each method signature in the interface. |
| What two things must your program do to respond to a particular type of event? | Create an event listener object for the type of event, and register it with the object that generates those events. |
| In Java, what do you call an area on the screen that has nice borders and various buttons along the top border? | A frame. |
| The DYNAMIC type of any variable refers to | the actual run-time type of the real object that the variable holds a reference to. |
| The STATIC type of any variable refers to | the declared compile-time type of the the variable. |
| Can an abstract parent class have non-abstract children? | Yes—an abstract parent can have both abstract and non-abstract children. |
| What is an abstract class? | An abstract class is class which cannot be instantiated. |
| What must be true if a child of an abstract parent class does not override all of the parent's abstract methods? | The child class itself must be declared to be abstract. |
| An object that waits for and responds to an event from a GUI component is a: | event listener |
| Here is an abstract method defined in some abstract parent class: public abstract int sumUp ( int[] arr ); Which of the following is required by all of it's non-abstract child classes? | public int sumUp ( int[] arr ) { . . . } |
| How is a GUI component (such as a button) placed into a JFrame? | getContentPane().add( Component c ) |
| What letter do many Swing class names start with? | J |
| Can an abstract class define both abstract methods and non-abstract methods? | Yes - but the child classes must define the body of abstract methods |
| What must be true if a child of an abstract parent class does not override all of the parent's abstract methods? | The child class itself must be declared to be abstract. |
| What is an abstract method? | An abstract method is one without a body that is declared with the reserved word abstract. |
| When a class implements an interface, what must it do? | It must declare identical signatures and provide a method body for each method signature in the interface. |
| Can an interface ever contain method bodies? | No. |
| A child class can extend ___ parent(s) and can implement ___ interfaces. | just one parent; zero or more interfaces |
| What is an abstract class? | a class which cannot be instantiated. |
| Can an interface name be used as the type of a variable? | Yes - the variable can refer to any object whose class implements the interface. |
| What method is used to read the text from a JTextField? | getText() |
| [T/F] A checked exception is any exception checked for by the compiler. | True |
| ____ is when a program is written to respond to button clicks, menu selections, user actions | Event-driven programming |
| When the user clicks on a button, what is generated? | An event |
| What is a container object in GUI programming? | A container is a GUI component that has other GUI containers placed inside of it. |
| Which of the following is an exception thrown by the methods of the class String? | NullPointerException |
| In which of the following layout managers do all rows (columns) have the same number of components and all components have the same size? | GridLayout |
| When is a finally{} block executed? | Always after the execution of a try block, regardless of whether or not an exception is thrown. |
| How many finally blocks can there be in a try/catch structure? | There can be 0 or 1 following the last catch block. |
| If the user changes the size of the frame, what happens to the graphical components? | The layout manager changes the layout and redistributes the components. |
| Every try block: | must have one or more catch blocks |
| What can a method do with a checked exception? | Throw the exception to the method that called this method, or handle the exception in a catch block. |
| What happens when there is no catch block following the try block? | The program will not compile |
| What is the purpose of the Graphics object? | It provides the underlying framework for java graphics operations |
| What type of object determines where GUI components go in the content pane? | The layout manager |
| Which manager displays components in the possible locations of north, south, east, west, center? | BorderLayout |
| Must a program respond to all events that its components generate? | No - it can safely ignore events that don't concern it |
| Components must be added to the window's ___ | content pane |
| Which manager displays components row-by-row, in order in which they were added? | FlowLayout |
| If a negative value is used for an array index, what exception is thrown? | IndexOutofBoundsException thrown |
| What is the name for a method that responds to events? | listener method |
| How does BoxLayout() put components into the content pane? | Either top to bottom (vertical), or left to right (horizontal) |
| The fundamental classes for GUI programming are contained in the: | Abstract Windowing Toolkit |
| Which class of exceptions is NOT checked? | RunTimeException |
| An abstract variable V is a mutable entity that admits two operations: | store(V, x), fetch(V) |
| An implementation detail, such as whether a method is recursive or iterative, should usually be ______ from the user. | hidden |
| A description of a software design pattern includes at least: | the consequences of using the pattern, the description of the problem that the pattern addresses, a name that can be used to conveniently talk about the pattern, a description of the solution |
| If a recursive algorithm does not make progress toward the base case, it could _____ | run forever or until the method call stack overflowed. |
| A suggested approach to discover the initial potential classes for a project is to extract the following from the project description and use cases: | List all of the verbs encountered. |
| [T/F] A "singleton" design pattern is used to ensure that only ONE instance of a class can be created. | true |
| [T/F] Scenarios are very technical problem descriptions that are best written by software engineers rather than the people familiar with the business problem. | false |
| The operations that modify a stack are: | push(), pop() |
| [T/F] A design pattern is a description of a common computing problem and a description of a small set of classes and their interaction structure that helps to solve that problem. | true |
| What are some of the key ACTIVITIES in software development? | Definition, Analysis, Design, Implementation, Deployment |
| A recursive definition is commonly one which defines the nth case in terms of the ______ case. | n - 1 |
| An iterative method ___ | uses less memory than a recursive method, uses some kind of loop as a control structure, is usually more efficient to execute than a recursive method |
| What are two parts to recursion? | (1) Directly solve the any of the easy problems, and (2) Decompose the harder problem into subproblems; solve the original problem in terms of the solutions to the subproblems. |
| What are two ways to view recursion? | i. static view; ii. dynamic view |
| Consider square numbers defined as follows: square(1) = 1 square(N) = square(N-1) + 2N -1 According to this definition, what is square(3)? | square(3) = square(2) + 2*3 - 1 |
| Say that you have an recursive Java method, compute(). Is it always possible to write a iterative version of compute( )? | Yes |
| The FACTORY design pattern's primary purpose is to: | create instances of objects |
| A base case is that part of a recursive definition that | stops the recursion from cycling endlessly. |
| [T/F] A "singleton" design pattern is used to ensure that only ONE instance of a class can be created. | True |
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