What is the output from this code segment? Assume that
floating-point values are printed to four decimal places
(e.g., 9.1234).
int x = 2, y = 3;
0!0.6666 0!0.0 0.6666!0.6666 0.0000!0.0000
Consider the code segment
public class SomeClass{
private int j;
public void m() {
int n;
}
public int p(int param) { return param / 2; }
}
What is the error?
p must be named n .n is used before being initialized.p cannot be written on a single line.
The following method is added to the class
SomeClass from Question 2.
public int myMethod(int k) {return (k + q) * j;}
Which of the following statements best describes the result of the compilation of the modified class?
k cannot be used in method myMethod because
it was already used in m q cannot be used in method myMethod because
it is local to the method m j cannot be used by methods myMethod
and m because it is declared private
Constructors are fundamental in the design and implementation of a class.
Which of the following statements is correct?
Which one of the following statements best describes how overloaded methods in the same
class can be differentiated from each other?
Consider the following
BankAccount class, which models a simplified bank account
public class BankAccount {
private double balance;
}
The following
Driver class attempts to instantiate a
BankAccount
object, withdraw money from it and print its current balance, but it generates compiler errors. Why? Choose the
answer that more accurately describes why it doesn't compile and how to
best fix it.
public class Driver {
public static void main(String[] args) {
BankAccount acct1 = new BankAccount(100);
}
}
non static variable
(balance ),
from a static environment. The variable balance
should be declared as static . int as parameter
(100) to the constructor
instead of the required double . You should pass 100.00 instead. balance is declared as private .
You should declare it as public instead.balance is declared as private .
You should create a public double getBalance() (getter ) method in the BankAccount class
and invoke it on acct1 instead.
Suppose
acct1 refers to a
BankAccount (from Question 6)
with a balance
of
$300.00 , while
acct2 refers to a
BankAccount with a balance of
$200.00 .
After the assignment
acct1 = acct2;
Which of the following is true?
$100.00 from acct1 will leave its balance at
$200.00 $100.00 from acct2
and then withdrawing $100.00 from acct1
will leave the balance of acct1 at
$200.00 $100.00 from acct2
and then withdrawing $100.00 from acct1
will leave the balance of acct1 at
$0.00
The following
Account class is a modification of the
BankAccount
from Question 6.
It contains a new variable,
trsnsactions , which keeps count of the number of deposits and withdraws,
and the corresponding
getter method
getTrasnsactionsCount.
The
deposit and
withdraw methods have also been modified.
public class Account
{
private double balance;
private static int transactions=0;
public Account(double initialAmount){ balance = initialAmount; }
public static int getTransactionsCount(){ return transactions; }
public void deposit(double amount) {
balance += amount;
transactions++;
}
public void withdraw(double amount){
balance -= amount;
transactions++;
}
}
What is the output of the following
Driver class?
public class Driver {
public static void main(String[] args) {
Account acct1 = new Account(100.0);
}
}
2 3 3 3 2 0 Driver class will not compile
because of the invalid method call:
acct2.getTransactionsCount() . You can't invoke a
static method on an object. Driver class will not compile
because of the invalid method call:
Account.getTransactionsCount() .
Account was never instantiated.
Given the class
public class Test {
private int k;
}
What is the output from the code segment below?
Test test1 = new Test(3);
3 5 0 4 5 6 4 4 3 4 6 7
The class
Z
public class Z {
int k;
public Z(int n) { k = n; }
public void m(int n, boolean b) {
if (b == true) k -= n;
}
public void m(int n) { k += n; }
public void dump() {
System.out.print(k + " ");
}
}
has three methods and a field. What is the output from
the code segment
Z obj = new Z(6);
14 15 15 18 15 14 13 17 14 15 18 14
What is the output from this code segment?
int[ ] nums = {9, 7, 5, 3, 1};
int i = nums.length - 1;
while (i > 0) {
System.out.print(nums[i] + " ");
}
3 5 7 9 1 3 5 3 1 3 5 7 9 7 3 5 1 1 3 5 7
What is the output from this code segment?
String[ ] strings = new String[5];
String prefix = "Q";
for (int i = 0; i < strings.length; i++)
strings[i] = prefix + i;
String[ ] more_strings = new String[strings.length];
int k = 0;
for (int j = strings.length - 1; j >= 0; j--)
more_strings[j] = strings[k++].toLowerCase();
int i = 0;
while (i < strings.length)
System.out.print(more_strings[i++] + " ");
Q1 Q2 Q3 q4 q4 q3 q2 q1 q0 q4 q3 q2 q1 q0 q1 q2 q3 q4
Here is a class
R with three methods:
public class R {
public void foo(int n) {
if (n == 0) print(n);
}
void bar(int n) {
print(n);
}
void print(int p) {
System.out.print(p + " ");
}
}
What is the output from the code segment
R obj = new R();
-3 -2 -1 0 -2 -1 0 1 -2 -1 -3 -2 -1 -4 -3 -2 -1 0
What is wrong with the following assignment statement?
boolean ok = 1;
1B rather than 1 .:= , not = .int value cannot be assigned to a boolean variable.
Here is the method named
mys
int mys(int[ ] array) {
int n = 1;
for (int i = 1; i < array.length; i++)
if (array[i] < array[i - 1]) n++;
return n;
}
and a code segment that invokes the method mys
int[ ] nums = {13, 11, 15, 9, 7, 5, 8, 3, 1};
What does the code segment print?
2 3 4 5
The code segment
int i = 0;
int n = 11;
while (i < n)
if (n % 2 == 0) n = n + 1;
How many times does the body of the while loop execute?
9 10 11
The code segment below contains a
for loop and
do/while loop.
int i;
int k = 5;
for (i = 1; i <= k; i++)
System.out.println(i);
i = 0;
do {
System.out.println(++i);
} while (i <= k);
Which of the following best describes the behavior of the two loops?
for loop executes more than the body of the
do/while loop.do/while loop executes nine times, whereas
the body of the for loop executes seven times.do/while loop executes one time more than
does the body of the for loop.
The code segment below contains a
for loop and
do/while loop.
The
do/while loop is changed from Question 17 but the
for loop is the same as in Question 17.
int i;
int k = 5;
for (i = 1; i <= k; i++)
System.out.println(i);
i = 0;
do {
System.out.println(i);
} while (i++ <= k);
Which of the following best describes the behavior of the two loops?
do/while loop executes one more time than
does the body of the for loop.do/while loop executes two more times than does
the body of the for loop.do/while loop executes three more times than
does the body of the for loop.
The class java.nio.ByteBuffer has two overloads for the method
putChar . The two declarations are:
ByteBuffer putChar(char value);
The following code segment uses the ByteBuffer class:
// Allocate a ByteBuffer with a capacity of 100.
The following questions refer to the
putChar statements by their
reference numbers: 1, 2, 3, and 4.
putChar calls are correct.putChar calls is correct.putChar call 2 is incorrect.putChar calls 3 and 4 are incorrect.
Consider the following modified
BankAccount class
public class BankAccount {
private double balance;
}
What output will running the
Driver class produce?
public class Driver{
public static void RVS(BankAccount[ ] anArray){
BankAccount temp;
int left = 0;
int right = anArray.length -1;
while (left < right) {
temp = anArray[left];
}
}
public static void main(String[] args){
BankAccount[] bank = new BankAccount[3];
for(int i=0; i<bank.length; i++)
bank[i]= new BankAccount(i*100);
RVS(bank);
for(int i=0; i<bank.length; i++)
System.out.println(bank[i]);
}
}
What does the method
mys return when called with an
argument of 6?
int mys(int n) {
int k = n;
int s = 1;
while (k > 1)
s *= k--;
return s;
}
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