Moment 5

Question 1

What dose the technique “divide and conquer” entail?

Answer 1

Experience has shown that the best way to develop and maintain a large program is to construct it from small, simple pieces. This technique is called divide and conquer

Question 2

Methods are declared within?

Answer 2

classes

Question 3

Classes are typically grouped into packages so they can be?

Answer 3

imported and reused.

Question 4

Methods allow you to modularize a program by?

Answer 4

separating its tasks into self-contained units. The statements in a method are written only once and hidden from other methods.

Question 5

Using existing methods as building blocks to create new programs is a form of?

Answer 5

software reusability (p. 206) that allows you to avoid repeating code within a program.

Question 6

A method call specifies the?

Answer 6

name of the method to call and provides the arguments that the called method requires to perform its task. When the method call completes, the method returns either a result, or simply control, to its caller.

Question 7

A class may contain static methods to perform?

Answer 7

common tasks that do not require an object of the class. Any data a static method might require to perform its tasks can be sent to the method as arguments in a method call.

Question 8

A static method is called by?

Answer 8

specifying the name of the class in which the method is declared followed by a dot (.) and the method name, as in:

ClassName.methodName(arguments)

Question 9

Class Math provides static methods for performing?

Answer 9

common mathematical calculations.

Question 10

The constant Math.PI (3.141592653589793; p. 208) is the?

Answer 10

ratio of a circle’s circumference to its diameter.

Question 11

The constant Math.E (2.718281828459045; p. 208) is the?

Answer 11

base value for natural logarithms (calculated with static Math method log).

Question 12

Math.PI and Math.E are declared with the?

Answer 12

modifiers public, final and static. Making them public allows you to use these fields in your own classes.

Question 13

A field declared with keyword final (p. 209) is?

Answer 13

constant—its value cannot be changed after it’s initialized.

Question 14

Both PI and E are declared final because?

Answer 14

their values never change. Making these fields static allows them to be accessed via the class name Math and a dot (.) separator, just like class Math’s methods.

Question 15

When you execute the Java Virtual Machine (JVM) with the java command, the JVM loads the class you specify and?

Answer 15

uses that class name to invoke method main. You can specify additional command-line arguments (p. 209) that the JVM will pass to your application.

Question 16

What method will be called by the java command?

Answer 16

You can place a main method in every class you declare—only the main method in the class you use to execute the application will be called by the java command.

Question 17

Class, method and variable names are?

Answer 17

identifiers.

By convention all use camel case names. Class names begin with an uppercase letter, and method and variable names begin with a lowercase letter.

Question 18

Parameters are declared in?

Answer 18

a comma-separated parameter list (p. 211), which is located inside the parentheses that follow the method name in the method declaration. Multiple parameters are separated by commas. Each parameter must specify a type followed by a variable name.

Question 19

Every method’s body is delimited by?

Answer 19

left and right braces ({ and }).

Question 20

Each method’s body contains one or more statements that?

Answer 20

perform the method’s task(s).

Question 21

The method’s return type specifies the?

Answer 21

type of data returned to a method’s caller.

Question 22

Keyword void indicates that?

Answer 22

a method will perform a task but will not return any information.

Question 23

Empty parentheses following a method name indicate that?

Answer 23

the method does not have parameters.

Question 24

When a method that specifies a return type (p. 211) other than void is called and completes its task, the method must?

Answer 24

return a result to its calling method.

Question 25

The return statement (p. 212) passes a?

Answer 25

value from a called method back to its caller.

Question 26

When a method is called, the program makes a copy of?

Answer 26

the method’s argument values and assigns them to the method’s corresponding parameters.

Question 27

When program control returns to the point in the program where the method was called, the method’s parameters are?

Answer 27

removed from memory.

Question 28

Strings can be concatenated (p. 212) using?

Answer 28

operator +, which creates a new String containing the characters of the left operand followed by those of the right operand.

Question 29

Every primitive value and object in Java can be represented as a?

Answer 29

String. When an object is concatenated with a String, the object is converted to a String, then the two Strings are concatenated.

Question 30

The word “true” or the word “false” is used to?

Answer 30

represent a boolean value as a String.

Question 31

All objects in Java have a special method named toString that returns a?

Answer 31

String representation of the object’s contents.

When an object is concatenated with a String, the JVM implicitly calls the object’s toString method to obtain the string representation of the object.

Question 32

You can break large String literals into?

Answer 32

several smaller Strings and place them on multiple lines of code for readability, then reassemble the Strings using concatenation.

Question 33

There are three ways to call a method, which?

Answer 33

using a method name by itself to call another method of the same class 
using a variable name, followed by a dot (.)  and a method name to call a non-static method of an object 
using the class name and a dot (.) to call a static method of a class.

Question 34

A static method can call directly only?

Answer 34

other static methods of the same class and can manipulate directly only static variables in the same class.

Question 35

There are three ways to return control to the statement that calls a method, which?

Answer 35

when the methodending right brace is reached in a method with return type void

when the following statement executes in a method with return type void:
return;

when a method returns a result with a statement of the following form in which the expression is evaluated and its result (and control) are returned to the caller:
return expression;

Question 36

Stacks are known as?

Answer 36

last-in, first-out (LIFO) data structures ()—the last item pushed (inserted) onto the stack is the first item popped (removed) from the stack.

Question 37

A called method must know how to return to its caller, so the?

Answer 37

return address of the calling method is pushed onto the method-call stack when the method is called.
If a series of method calls occurs, the successive return addresses are pushed onto the stack in last-in, first-out order so that the last method to execute will be the first to return to its caller.

Question 38

The method-call stack contains the memory for?

Answer 38

the local variables used in each invocation of a method during a program’s execution. This data is known as the method call’s stack frame or activation record.

Question 39

When a method call is made, the stack frame for that method call is?

Answer 39

pushed onto the method-call stack.

Question 40

When the method returns to its caller, its stack frame is?

Answer 40

popped off the stack and the local variables are no longer known to the program.

Question 41

If there are more method calls than can have their stack frames stored on the method-call stack,
an error known as a?

Answer 41

stack overflow occurs. The application will compile correctly, but its execution causes a stack overflow.

Question 42

Argument promotion (p. 215) converts an argument’s value to?

Answer 42

the type that the method expects to receive in its corresponding parameter.

Question 43

Promotion rules (p. 215) apply to expressions containing values of?

Answer 43

two or more primitive types and to primitive-type values passed as arguments to methods. Each value is promoted to the
“highest” type in the expression.

In cases where information may be lost due to conversion, the Java compiler requires you to use a cast operator to explicitly force the conversion to occur.

Question 44

Objects of class SecureRandom (package java.security; p. 218) can?

Answer 44

produce nondeterministic random values.

Question 45

SecureRandom method nextInt (p. 219) generates a?

Answer 45

random int value.

Question 46

Class SecureRandom provides another version of?

Answer 46

method nextInt that receives an int argument and returns a value from 0 up to, but not including, the argument’s value.

Question 47

Random numbers in a range (p. 219) can be generated with?

Answer 47

int number = shift + randomNumbers.nextInt(scale);

where shift specifies the first number in the desired range of consecutive integers, and scale specifies how many numbers are in the range.

Question 48

Random numbers can be chosen from nonconsecutive integer ranges, as in?

Answer 48

int number = shift + difference * randomNumbers.nextInt(scale);

where shift specifies the first number in the sequence, difference represents the difference between consecutive numbers in the sequence and scale specifies how many numbers are in the sequence.

Question 49

An enum type (p. 226) is introduced by?

Answer 49

the keyword enum and a type name. As with any class, braces ({ and }) delimit the body of an enum declaration. Inside the braces is a comma-separated list of enum constants, each representing a unique value. The identifiers in an enum must be unique. Variables of an enum type can be assigned only constants of that enum type.

Question 50

Constants can also be declared as?

Answer 50

private static final variables.

Such constants are declared by convention with all capital letters to make them stand out in the program.

Question 51

Scope (p. 227) is the portion of the program in which an?

Answer 51

entity, such as a variable or a method, can be referred to by its name. Such an entity is said to be “in scope” for that portion of the program.

Question 52

The scope of a parameter declaration is the?

Answer 52

body of the method in which the declaration appears.

Question 53

The scope of a local-variable declaration is from?

Answer 53

the point at which the declaration appears to the end of that block.

Question 54

The scope of a local-variable declaration that appears in the initialization section of a for statement’s header is the?

Answer 54

body of the for statement and the other expressions in the header.

Question 55

The scope of a method or field of a class is the?

Answer 55

entire body of the class.

Question 56

Any block may contain variable declarations. If a local variable or parameter in a method has the same name as a field, the field is?

Answer 56

shadowed (p. 228) until the block terminates execution

Question 57

Java allows overloaded methods (p. 230) in a class, as long as the methods have?

Answer 57

different sets of parameters (determined by the number, order and types of the parameters).

Question 58

Overloaded methods are distinguished by their?

Answer 58

signatures (p. 231)—combinations of the methods’ names and the number, types and order of their parameters, but not their return types.

Question 59

A method is invoked with a(n)?

Answer 59

method call.

Question 60

A variable known only within the method in which it’s declared is called a(n)?

Answer 60

local variable.

Question 61

The ___________________ statement in a called method can be used to pass the value of an expression
back to the calling method.

Answer 61

return.

Question 62

The keyword _______________ indicates that a method does not return a value.

Answer 62

void.

Question 63

Data can be added or removed only from the _______________ of a stack.

Answer 63

top.

Question 64

Stacks are known as _______________ data structures; the last item pushed (inserted) onto the stack is the first item popped (removed) from the stack.

Answer 64

last-in, first-out (LIFO).

Question 65

The three ways to return control from a called method to a caller are ___________ , ____________ and ___________ .

Answer 65

return; or return expression; or encountering the closing right brace of a method.

Question 66

An object of class ________________ produces truly random numbers.

Answer 66

Secure- Random.

Question 67

The method-call stack contains the memory for local variables on each invocation of a method during a program’s execution. This data, stored as a portion of the method-call stack, is known as the _____________ or ___________ of the method call.

Answer 67

stack frame, activation record.

Question 68

If there are more method calls than can be stored on the method-call stack, an error known as a(n) ______________ occurs.

Answer 68

stack overflow.

Question 69

The _______________ of a declaration is the portion of a program that can refer to the entity in the declaration by name.

Answer 69

scope.

Question 70

It’s possible to have several methods with the same name, each operating on different types or numbers of arguments. This feature is called method _______________ .

Answer 70

overloading.

Question 71

Give the method header for each of the following methods:

a) Method hypotenuse, which takes two double-precision, floating-point arguments side1 and side2 and returns a double-precision, floating-point result.

Answer 71

double hypotenuse(double side1, double side2)

Question 72

Give the method header for each of the following methods:

b) Method smallest, which takes three integers x, y and z and returns an integer.

Answer 72

int smallest(int x, int y, int z)

Question 73

Give the method header for each of the following methods:

c) Method instructions, which does not take any arguments and does not return a value.
[Note: Such methods are commonly used to display instructions to a user.]

Answer 73

void instructions()

Question 74

Method intToFloat, which takes integer argument number and returns a float.

Answer 74

float intToFloat(int number)