Question 1

The Random class has a method, nextFloat() which returns a random float value between

Accepted Answer

The nextFloat() method of the Random class generates a random float value between 0 (inclusive) and 1 (exclusive), so option B is the correct choice. The other options all have incorrect ranges.

Question 2

Assume that x and y are ints equal to 10 and 5 respectively. What is the output of the following statement? System.out.println(x + y);

Accepted Answer

The statement will output the result of adding x and y, which is 15.

Question 3

Which library package would you import to use the class Random?

Accepted Answer

The class Random is part of the java.util package, so you would need to import that package to use it. The other packages listed (java.beans, java.io, java.lang, and java.text) do not contain the Random class.

Question 4

A Java variable is the name of a

Accepted Answer

A Java variable can change its value during the program's execution, but its type cannot change. Therefore, choice C is the correct answer.

Question 5

Given String name = "Arleen Crabtree". What will the following instruction return? name.toUpperCase().replace('R', 'Z');

Accepted Answer

The method toUpperCase() will convert the entire string to uppercase, resulting in "ARLEEN CRABTREE". Then, the method replace('R', 'Z') will replace all occurrences of the character 'R' with the character 'Z', resulting in "AZLEEN CZABTREE".

Question 6

Of the following types, which one cannot store a numeric value?

Accepted Answer

The char data type can only store a single character or ASCII value, not a numeric value.

Question 7

If x is an int and y is a float, which of the following statements is not a legal assignment statement?

Accepted Answer

Assigning a float to an int is a narrowing conversion and may result in a loss of precision, so it requires an explicit cast (as in option D). However, assigning an int to a float is a widening conversion, which can be done implicitly without a cast (as in options A and C).

Question 8

If you want to output a double so that at least one digit appears to the left side of the decimal point and exactly one digit appears to the right side, which pattern would you give a DecimalFormat variable when you instantiate it?

Accepted Answer

The pattern "0.0" ensures that at least one digit appears to the left of the decimal point and exactly one digit appears to the right, meeting the specified formatting requirements.

Question 9

Which library package would you import to use NumberFormat and DecimalFormat?

Accepted Answer

NumberFormat and DecimalFormat classes are part of the java.text package.

Question 10

Assume that x, y, and z are all ints equal to 50, 20, and 6 respectively. What is the result of: x / y / z

Accepted Answer

In Python, the division of integers where the result is a fraction less than 1 will result in 0 because it performs floor division when using integers. Here, x / y / z = 50 / 20 / 6 = 2.5 / 6 = 0.416..., which when floored (in integer division) results in 0.

Question 11

Which of the following would return the last character of the String x?

Accepted Answer

The answer of Which of the following would return the...

Question 12

What is the value of z after the following assignment statement is executed? float z = 5/10;

Accepted Answer

The division 5/10 is performed as integer division because both operands are integers, resulting in 0. When assigned to a float variable, the result is 0.0.

Question 13

Given the double likelihood = 0.013885 and given DecimalFormat dformatter = DecimalFormat("0.00##");
What would be the output if you execute the following:
System.out.println(df.format(likelihood));

Accepted Answer

The decimal formatter "0.00##" indicates that there should be two decimal places no matter what, and then include additional decimal places if there are non-zero digits. So, when we format the double likelihood = 0.013885, it will round to 0.0139 because the next decimal place is a 5, which rounds up since it is even. Therefore, the output will be 0.0139.

Question 14

If the String major = "Computer Science", what is returned by major.charAt(1)?

Accepted Answer

The charAt() method of a String returns the character at the specified index. In the string "Computer Science", the character at index 1 is "o".

Question 15

Assume that x and y are ints equal to 10 and 5 respectively. What is the output of the following statement? System.out.println("" + x + y);

Accepted Answer

The statement concatenates the value of x and y as strings. Therefore, the output will be "105".

Question 16

Which of the following is true regarding the mod operator, %?

Accepted Answer

The mod operator, %, can be applied to any numeric types (integers, floats, doubles, etc.), and the result is always of a numeric type, matching the type of the operands involved. It returns the remainder of a division operation.

Question 17

Which of the following situations would require a cast?

Accepted Answer

Storing a float in an int requires a cast because the data types are not compatible. The other options do not require casting because they involve data type conversions that are allowed by Java's widening rules.

Question 18

If you want to store the value "Harry Potter" in the String variable name, which of the following statements could you use?

Accepted Answer

All the options provided are valid ways to store the string "Harry Potter" in a String variable named name in Java. Option A directly assigns the string, option B uses the String constructor, option C concatenates strings, and option D combines string concatenation with the String constructor.

Question 19

Using getCurrencyInstance() formats a variable, automatically inserting

Accepted Answer

The getCurrencyInstance() method formats a variable by automatically inserting a decimal point for cents and a dollar sign (or the appropriate currency symbol for the locale), but it does not insert a percent sign, which is used for formatting percentages, not currencies.

Question 20

What will be the result of the following assignment statement, given that b = 5 and c = 10? int a = b * (-c + 2)/2;

Accepted Answer

a = b * (-c + 2)/2
a = 5 * (-10 + 2)/2
a = 5 * (-8)/2
a = -20

Quiz 2: Data and Expressions