Deck 1: Review of Java Fundamentals

Question 1

Which of the following loop headers will arrange for the loop body to execute exactly 10 times?

A)for (int i = 1;i < 10;++i)
B)for (int i = 0;i <= 10;++i)
C)for (int i = -5;i < 5;++i)
D)for (int i = 2;i < 20;++i)

Answer 1

C

Question 2

Which access modifier,used when defining a method,indicates that only one such method is available for all instances of the class?

A)final
B)private
C)protected
D)static

Answer 2

D

Question 3

When using the method System.out.printf( ),what is the purpose of the %d format code?

A)For printing a double
B)For printing a float
C)For printing a String
D)For printing an int

Answer 3

D

Question 4

Suppose c1 and c2 are objects of the class Circle.A Circle has a single data member,its radius.The Circle class has a default constructor (implemented correctly),but no other methods have been defined in the implementation of the Circle class.What will happen when we try to execute this code? Circle c1 = new Circle(12.0);
Circle c2 = new Circle(12.0);
Boolean same = (c1.equals(c2));

A)The code will not compile because equals( )has not been implemented in Circle.
B)The value of same will be true.
C)The value of same will be false.

Question 5

In Java,how do we tell the compiler that the body of a loop consists of several statements,rather than one?

A)We enter all the statements on the same line
B)We indent all the statements at the same level of indentation
C)We enclose the statements in curly braces
D)We insert a break statement at the end of the loop

Question 6

In order to declare a named constant,the declaration must use which Java keyword?

A)final
B)int
C)static
D)void

Question 7

Which type of loop is guaranteed to execute its body at least once?

A)do-while
B)for
C)switch
D)while

Question 8

A comment in Java that begins with /** and ends with */ is what kind of comment?

A)block comment
B)javadoc comment
C)line comment
D)nested comment

Question 9

Suppose a String variable s is initialized to the value "inheritance".What value is returned by the call s.substring(2,5)?

A)nher
B)nheri
C)her
D)heri

Question 10

If s1 is of type String,what does s1.compareTo(s1)return?

A)zero
B)true
C)false
D)Cannot be determined without knowing the value of s1.

Question 11

What feature of Java transforms class objects into a sequence of bytes that may be used by another program?

A)compilation
B)inheritance
C)serialization
D)tokenization

Question 12

What does it mean for the return type of a method to be void?

A)The method will never return a value.
B)The method will return the value zero.
C)The method does not take parameters.
D)The method does not have a body.

Question 13

What type of Java statement allows you to use classes contained in other packages?

A)an access statement
B)a class statement
C)an import statement
D)a package statement

Question 14

Suppose a try block needs to be followed by two catch blocks,each catching a different exception.Which exception should be caught first?

A)The exception that is more likely to occur
B)The exception that is more general
C)The exception that is more specific
D)It does not matter in what order exceptions are caught

Question 15

What is the meaning of the declaration: String [][] a = new String [60][80];?

A)Create an array of 60 strings,each of size 80 characters.
B)Create an array of 80 strings,each of size 60 characters.
C)Create a two-dimensional array of strings with 60 columns and 80 rows.
D)Create a two-dimensional array of strings with 60 rows and 80 columns.

Question 16

How many constructors can a class have?

A)Exactly one
B)At least one but no more than three
C)Exactly the same as the number of data members
D)There is no restriction on the number of constructors

Question 17

Which of the following is an example of a wrapper class?

A)Double
B)int
C)String
D)System

Question 18

Which of these expressions is illegal in Java?

A)x++ 5
B)x =+ 5
C)x += 5
D)x == 5

Question 19

Suppose s is of type String.What would it mean if s.lastIndexOf)returns the value 1?

A)The first character appears once in the string.
B)The first two characters in the string are identical.
C)The length of the string is 2.
D)The second character of the string is '0'.

Question 20

If x is a variable of type int,what is the largest possible value of the expression (x % 5)?

A)1
B)4
C)5
D)2³¹-1

Question 21

Short-circuit evaluation refers to:

A)Jumping from the try block to the catch block when an exception is thrown.
B)Avoiding the testing of a boolean condition that is unnecessary.
C)Truncating the integer result of a division operation.
D)Avoiding the execution of the else clause of an if-statement.

Question 22

The Java expression 9 / 5 + 9 % 5 equals ______.

A)0
B)1
C)3
D)5
E)6

Question 23

If we wanted to write an if-statement that executes whenever the real number x is between 10.0 and 20.0,how should the test condition be written?

A)10.0 < x || x > 20.0
B)10.0 < x && x > 20.0
C)10.0 < x && x < 20.0
D)10.0 < x || x < 20.0

Question 24

All Java classes must contain a method called main.

Question 25

Comments beginning with the characters // can extend for multiple lines until the compiler encounters \\.

Question 26

The Java expression (75 - 63)* 10 / 6 - 1 evaluates to 19.

Question 27

In Java,when we write an if-statement of the form if(condition),the condition must evaluate to a boolean value.

Question 28

If d is a double and i is an int,then the assignment statement d = i;is legal in Java.

Question 29

Which of these is not a legal Java identifier?

A)2be
B)to_be
C)TOBE
D)tobE

Question 30

A default constructor requires at least one parameter in order to compile correctly.

Question 31

All Java programs must define at least one class.

Question 32

A built-in class that helps to split strings into pieces,such as words of a sentence,is:

A)Console
B)Scanner
C)StringBuffer
D)StringTokenizer

Question 33

Consider the following code that appears in a test class. A a = new A();
Int c = a.b;
In order for this code to work,which statement must be true?

A)a must be declared public inside class A
B)b must be declared public inside class A
C)c must be declared public inside class A
D)Method b( )must return int

Question 34

Which is not a primitive type in Java?

A)String
B)float
C)double
D)long

Question 35

Integer literals beginning with the digit 0 are interpreted to be in decimal notation.

Question 36

If an int is added to a float,the result will be an int.

Question 37

A statement invoking a constructor should also use the Java keyword ______.

A)class
B)return
C)public
D)new

Question 38

How is the finally keyword used in Java?

A)To indicate that a method should terminate and pass a value to the calling environment.
B)To indicate the last statement that will execute in a program.
C)To indicate an action that should take place whether an exception occurred or not.
D)To indicate a termination condition for a loop.

Question 39

All classes extend which built-in class?

A)Main
B)Object
C)Simple
D)Super

Question 40

If s1 = "dog" and s2 = "cat",then s1.compareTo(s2)returns a positive integer value.

Question 41

If s = "hello,world" (with exactly one space between the comma and 'w'),what does s.indexOf(",")return?

Question 42

Suppose a class Planet had a method findLife( )that we call as follows in main( ):
int value = p.findLife("goat",true,0.5);
How would the findLife( )method be declared in Planet.java?

Question 43

Write a for-loop that will print all the positive integers from 100 down to 1,inclusive,one number per line.

Question 44

Suppose a,b and c are the lengths of the 3 sides of a triangle.Write an if-statement that will determine if the triangle is isosceles (at least 2 of the 3 sides are equal).You may assume that a,b and c are of type int.

Question 45

What is wrong with this Java statement? int num = new int(5);

Question 46

Why does the Java statement System.out.println("answer = " + 3 + 4);
not print answer = 7 ?

Question 47

Interpret the overall meaning of this if-statement:
if (num % 7 == 0 || num % 11 == 0)

Question 48

Suppose c is a variable of type char.We want to know if c is a lowercase vowel letter (a/e/i/o/u).What is wrong with the following comparison?
if (c == 'a' || 'e' || 'i' || 'o' || 'u')

Question 49

How many times are the indicated statements (#1)and #2)each executed?
for (int i = 1;i <= 10;++i)
for (int j = 1;j <= 10;++j)
for (int k = 1;k <= 5;++k)
++count; // statement #1
System.out.printf("%d\n",count);// statement #2

Question 50

The following code containing a loop attempts to find how many times the letter 'r' appears in a string.But something is wrong with the loop.How would you fix it?
String s = "railroad";
int count = 0;
char letter = s.charAt(index);
for (int index = 0;index < s.length();++index)
if (letter == 'r')
++count;

Question 51

What is the value of sum after the following code executes?
int sum = 0;
int count = 0;
while (count < 4)
{
sum += count / 2;
count += 1;
}

Question 52

Complete the following code so that it sets found to true if the array a consisting of integers contains the value zero.
int index = 0;
boolean found = false;

Question 53

Suppose s1 is a String variable.We want to check to see if the first and last characters of s1 are the same.Complete the following if-statement to accomplish the task.
boolean same;
if (______________________________________________)
same = true;
else
same = false;

Question 54

Suppose temp is an array of 12 double values that holds the average temperatures of the 12 months of the year,January through December,in that order.Use Java to find the average of the temperatures for the 3 summer months,June,July and August only,and set this answer to the variable summerAverage.

Question 55

The following code attempts to find the sum of the elements in the third column (from the left)of a two dimensional int array called a that has 10 rows and 20 columns.Correct the errors in the code.
int sum = 0;
for (int i = 0;i < 20;i++)
sum = sum + a[3][i];

Question 56

Suppose a is a one-dimensional array of double.Show how you would find the largest element of a using Java code.

Question 57

What will happen when you try to run a program that has a syntax error?

Question 58

What is wrong with this loop? How would you fix it?
int num = 1;
while (num <= 10){
System.out.println("num = " + num);
}

Question 59

Suppose x and y are int variables.Write a statement that declares the boolean variable between,and sets this variable equal to true if the value of y is between 0 and x,inclusive,and equal to false otherwise.(Assume that you don't know if x is positive or negative. )

Question 60

A leap year occurs when the year number is divisible by 4.But there is a special case for years ending in 00: these must be divisible by 400 to be considered a leap year.Thus,1900 was not a leap year,but 2000 was.Write an if-statement that determines if the integer variable year represents a leap year.(Hint: use the % operator for taking remainders. )