Deck 3: Introduction to Objects and Input/output

Question 1

In a string, the index (position) of the first character is 1.

Answer 1

False

Question 2

In order to use a predefined method, you only need to know the name of the method and the type of each parameter.

Answer 2

False

Question 3

To use the contents of the java.lang package in a program, they must be imported using the import statement.

Answer 3

False

Question 4

Suppose z = 1834.762. The output of the statementSystem.out.printf("%.1f", z);is 1834.800.

Question 5

The dot (.) operator is also called the member specific operator.

Question 6

The method printf is used only to format the output of integers and decimal numbers.

Question 7

The new operator is used to create an int variable.

Question 8

The value of the expression Integer.parseInt("+782") is "782".

Question 9

Java provides automatic garbage collection.

Question 10

Given int num; the value of num is directly stored in its memory space.

Question 11

If length denotes the length of a nonnull string, then length - 1 gives the index of the last character in the string.

Question 12

The default output of decimal numbers of the type float is up to nine decimal places.

Question 13

Reference type variables directly store data into their memory space.

Question 14

String objects are mutable.

Question 15

In a format specifier, if the flag is set to 'l', then the output of the result is left justified.

Question 16

The classes Integer, Float, and Double are called wrapper classes.

Question 17

Suppose that name is a String variable. Then the following two statements are equivalent.name = "Danny";
name = new String("Danny");

Question 18

In the class String, the substring method inserts a string into another string.

Question 19

In a format specifier, the option width specifies the maximum number of characters to be written to the output.

Question 20

String variables are reference variables.

Question 21

Which of the following method is contained in the package java.util?

A) format
B) Integer
C) nextInt
D) printf

Question 22

What will most probably happen if you omit the dot operator when accessing a method?

A) An exception will be thrown.
B) The computer will crash.
C) A syntax error will be reported.
D) The program will execute as planned.

Question 23

What is the value of the following statement?
Math.pow(3,4)

A) 7
B) 12
C) 34
D) 81

Question 24

Suppose the String variable str points to the String object "Sunny day" at the memory address 3600. Then the value of str is:

A) the memory address 3600
B) "Sunny day"
C) 3600 + "Sunny day"
D) None of these

Question 25

In Java, all variables declared using a class are ____.

A) primitive variables
B) reference variables
C) constants
D) operators

Question 26

The class JOptionPane allows a programmer to use graphical interface components to obtain input from a user.

Question 27

An expression such as str.length(); is an example of a(n) ____.

A) system call
B) object call
C) class
D) method call

Question 28

Which package is automatically imported by the Java system?

A) java.io
B) java.lang
C) java.util
D) java.swing

Question 29

There are ____ type(s) of methods in a class.

A) one
B) two
C) three
D) four

Question 30

Which of the following is the member access operator?

A) +
B) .
C) -
D) ->

Question 31

The statement System.exit(0); is found at the end of every working Java program.

Question 32

Which statement instructs a program to run the garbage collector?

A) System.clearGarbage();
B) System.flushGarbage();
C) System.out();
D) System.gc();

Question 33

String sentence;
String str1, str2, str3, str4;
Int length1;sentence = "First exam is on Monday.";str1 = sentence.substring(6, 12);
Str2 = str1.substring(0, 4);
Str3 = sentence.replace('i', '#');
Str4 = sentence.indexOf("on");length1 = sentence.length();Based on the code above, what is the value of length1?

A) 20
B) 21
C) 24
D) 26

Question 34

String sentence;
String str1, str2, str3, str4;
Int length1;sentence = "First exam is on Monday.";str1 = sentence.substring(6, 12);
Str2 = str1.substring(0, 4);
Str3 = sentence.replace('i', '#');
Str4 = sentence.indexOf("on");length1 = sentence.length();Based on the code above, what is the value of str1?

A) exam i
B) exam
C) exam is
D) on Monday

Question 35

When writing output to a file, if the file is not closed at the end of the program, you may not be able to view your output properly.

Question 36

Given a decimal number, the method format of the class String returns the string containing the digits of the formatted number.

Question 37

Which of the following is a valid statement?
(i) int num = new int(67);
(ii) String name = new ("Doe");
(iii) String name = "Doe";

A) Only (i)
B) Only (i) and (ii)
C) Only (iii)
D) Only (ii) and (iii)

Question 38

Suppose str is a String variable. The statement str = new String("Programming"); is similar to which of the following?

A) new String = "Programming";
B) String new = "Programming";
C) str = "Programming";
D) str new "Programming";

Question 39

The class JOptionPane is part of the package java.swing.

Question 40

String sentence;
String str1, str2, str3, str4;
Int length1;sentence = "First exam is on Monday.";str1 = sentence.substring(6, 12);
Str2 = str1.substring(0, 4);
Str3 = sentence.replace('i', '#');
Str4 = sentence.indexOf("on");length1 = sentence.length();Based on the code above, what is the value of str2?

A) Firs
B) First
C) Monda
D) exam

Question 41

What is the output of the following statement?System.out.printf("%.2f", 48.9);

A) 48.00
B) 48.90
C) 49
D) 49.00

Question 42

Which of the following is an area of secondary storage used to hold information?

A) file
B) variable
C) constant
D) buffer

Question 43

Which of the following outputs 56734.9875 to three decimal places?

A) System.out.printf("3f%", 56734.9875);
B) System.out.printf(".3f%", 56734.9875);
C) System.out.printf(".03f%", 56734.9875);
D) System.out.printf("%.3f", 56734.9875);

Question 44

The showMessageDialog method has ____ parameter(s).

A) one
B) two
C) three
D) four

Question 45

String sentence;
String str1, str2, str3, str4;
Int length1;sentence = "First exam is on Monday.";str1 = sentence.substring(6, 12);
Str2 = str1.substring(0, 4);
Str3 = sentence.replace('i', '#');
Str4 = sentence.indexOf("on");length1 = sentence.length();Based on the code above, what is the value of str3?

A) "First exam is on Monday."
B) "F#rst exam #s on Monday."
C) "F#rst exam is on Monday."
D) "#i### #### i###########."

Question 46

Consider the following statements.double x;
String y;y = String.format("%.2f", x);If x = 285.679, what is the value of y?

A) "285.00"
B) "285.680"
C) "285.68"
D) "285.068"

Question 47

String sentence;
String str1, str2, str3, str4;
Int length1;sentence = "First exam is on Monday.";str1 = sentence.substring(6, 12);
Str2 = str1.substring(0, 4);
Str3 = sentence.replace('i', '#');
Str4 = sentence.indexOf("on");length1 = sentence.length();Based on the code above, what is the value of str4?

A) 11
B) 12
C) 13
D) 14

Question 48

Which of the following statements would store input in name?

A) name = JOptionPane.showInputDialog("Enter your name and press OK");
B) name = JOptionPane.showMessageDialog("Enter your name and press OK",
JOptionPane.PLAIN_MESSAGE, null);
C) name = System.in();
D) name = JOptionPane.input("Enter your name and press OK");

Question 49

What happens when JOptionPane.PLAIN_MESSAGE is chosen as the messageType parameter?

A) No icon is displayed in the dialog box.
B) An X is displayed in the dialog box.
C) A question mark is displayed in the dialog box.
D) An exclamation point is displayed in the dialog box.

Question 50

Suppose that you have the declaration:int num = 94;
Double x = 73.92;
String str = "Programming";What is the output of the following statements?System.out.println("123456789012345678901234567890");
System.out.printf("%5d%6.2f %15s%n", num, x, str);

A) 123456789012345678901234567890
94 73.92 Programming
B) 123456789012345678901234567890
94 73.92 Programming
C) 123456789012345678901234567890 94 73.92 Programming
D) 123456789012345678901234567890
94 73.92 Programming