study guide for Comp Sci A

following questions

100

Which of the following is used to indicate a new line?

\n

200

Which of the following is a legal variable name in Java?

ans

300

Which of the following is NOT a primitive data type?

String

400

Which of the following variable assignments is legal in Java?

double n = 3;

500

Which of the following correctly stores the word umbrella in a variable called stuff?

String stuff = "umbrella";

output solving

100

What is output?
System.out.println("The answer is: " + 5 + 19);

The answer is: 519

200

Consider the following code:

int c = 3 - 37 % 2;
System.out.println ( c );

What is the output?

2

300

Consider the following code:

double x = -97.6;
System.out.println(Math.abs(x));

What is output?

97.6

400

What is output by the following code?

int x = 36 % 8;
if (x >= 10)
System.out.println(1);
else if (x >= 8)
System.out.println(2);
else if (x >= 6)
System.out.println(3);
else if ( x >= 4)
System.out.println(4);
else
System.out.println(5);

4

500

Consider the following code:

String words [] = {"avalanche", "budget", "cannot", "center", "meaning", "clear", "furniture", "deep", "piccolo", "friendly", "potatoes"};
int c = 0;
for(int i = 0; i < words.length; i++) {
if (words[i].substring(0,3).indexOf('o') >= 0)
c++;
}
System.out.println( c );

What is output?

1

If Statements

100

What are if statements used for in programs?

Making decisions

200

Which if statement below tests if letter holds R? (letter is a char variable)

if (letter == 'R')

300

Which if statement below tests if the variable letter holds the char value w?

if ( letter == 'w')

400

What does short circuit evaluation mean in the following code?

if ( a < b || c != d )

if a < b is true it doesn't evaluate c != d

500

The following if statement tests the rainfall in New York's Central Park during the months of June, July and August.

if (low <= rain && rain <= high)
System.out.println("Rainfall amount is normal.");
else
System.out.println("Rainfall amount is abnormal.");

It could be replaced with:

II only

if (rain >= low) {
if (rain <= high)
System.out.println("Rainfall amount is normal.");
else
System.out.println("Rainfall amount is abnormal.");
} else
System.out.println("Rainfall amount is abnormal.");

missing code

100

Consider the following code, intended to search an array for a value and print the position where that value was found:

int [] array = / Assume array is correctly initialized /;
int num = / Input from the keyboard /;
int position = -1;
for (int i = 0; i < array.length; i++) {
if ( array[i] == num )
/ Missing Code /
}
if (position == -1)
System.out.println("Value not found");
else
System.out.println("Value found at position " + position);

What could replace / Missing Code / so that the code works as intended?

position = i;

200

The following is intended to count the number of times the number 87 is found in an array of test scores:

int [] d = / Assume array is initialized /;
int scoreCount = 0;
for (int i = 0; i < d.length; i++) {
if (/ Missing Code /)
scoreCount++;
}
System.out.println("Number of 87's: " + scoreCount);

Which of the following could replace / Missing Code / so that the code works as intended?

d[i] == 87

300

Consider the following code, intended to count the number of words in the array with a length less than or equal to 6.

String vocabulary [] = / Array initialized with Strings /;
int c = 0;
for (int i = 0; i < vocabulary.length; i++) {
if ( / Missing Code /)
c++;
}
System.out.println("Number of words with length less than or equal to 6: " + c);

What could be used to replace / Missing Code / so that the code works as intended?

vocabulary[i].length() <= 6

400

The following is intended to return the location of the first instance of the String the user enters from the keyboard, -1 if not found.

String names [] = new String[20];
//assume array is initialized

System.out.println("Enter a name to search for: ");
String lookingFor = scan.nextLine();

int found = -1;

for (int i = 0; i < names.length; i++) {
if ( / Missing Code / ) {
found = i;
break;
}
}

Which of the following could replace / Missing Code / so that it works as intended?

lookingFor.equals(names[i])

500

Consider the following method checking whether a student has passing grades:

public boolean isPassing(int finalExam, int cumulativeAverage) {
/ Missing Code /
}
A student can pass a class if one of the following is true:

The final exam is at least 98
The cumulative average is over 60

Which of the following correctly replaces / Missing Code / so that the method works as intended?

I and II only

I.
if ((finalExam >= 98) || (cumulativeAverage > 60))
return true;
return false;

II.
boolean pass = false;
if (finalExam >= 98)
pass = true;
if (cumulativeAverage > 60)
pass = true;
return pass;

Random

100

Assuming that scan is a properly initialized Scanner variable, which of the following correctly inputs a String?

String val = scan.nextLine();

200

Which character below is not allowed in a variable name?

&

300

Which of the following would properly create A and B as integer variables?

int A, B;

400

What is the result of compiling and running the following code?

int s = Math.sqrt(26);

Error: possible loss of precision

500

Consider the following code:

double list [] = new double [50];

The index of the first value is _______ and the last index is ______.

0, 49