Finals Notes II

Question 1

How can you shorten x = x + 1 and x = x + y?

Answer 1

x++;
x += y;

Question 2

How do you import a scanner?

Answer 2

java.util.Scanner;

Question 3

What should you use after using nextInt() or nextDouble()?

Answer 3

input.nextLine();

Question 4

How do you state a new Scanner?

Answer 4

Scanner input = new Scanner(System.in)

Question 5

What is the stack?

Answer 5

• Stores local variables
• Stores references to objects in the heap
• Stores method calls
• Memory is allocated and freed automatically as methods are called and returned
• Follows LIFO (Last In, First Out) order

Question 6

What is the heap?

Answer 6

• Stores all objects (keywords, arrays, Strings, etc.)
• Stores instance variables inside objects
• Stores string literals in a String Pool

Question 7

What happens when you have String str1 = “abc” and String str2 = “abc”?

Answer 7

They both refer to the same object, saving memory from not creating a new object.

Question 8

What happens when you have String str1 = “abc” and String str3 = new String(“abc”)?

Answer 8

A new object is forced to be created. Str1 and str3 do not point to the same area.

Question 9

What is immutability?

Answer 9

Strings cannot be changed unless they are re-assigned.

Question 10

What are some escape sequences to help you use special characters in Strings?

Answer 10

• \” for quotations
• \ for backslashes
• \n for a line break
• \t for a tab space

Question 11

Compare these values in ASCII.
“A”.compareTo(“B”)
“test”.compareTo(“testing”)
“testing”.compareTo(“test”)

Answer 11

<0
<0
>0

Question 12

How do you make an array?

Answer 12

type[] name = new type[# of elements]

Question 13

What exception would you get for accessing a value outside an array?

Answer 13

ArrayIndexOutOfBoundsException

Question 14

How do you structure an enhanced for loop?

Answer 14

for (type loopName: dataName)
{ code here }

Question 15

What coordinate would you look at for gradeBook[2][1]?

Answer 15

(3, 2)

Question 16

In gradeBook[x][y], what is the row and what is the column?

Answer 16

x = row; y = column

Question 17

How do you declare a 2D array?

Answer 17

type[][] array = new type[x][y]

Question 18

What does array.length do for a 2D array?

Answer 18

Shows the number of rows.

Question 19

What does array[r].length do?

Answer 19

Shows the number of items of that row.

Question 20

public static int multiply(int a, int b) {
return a * b;
}
int product = multiply(x, y);

What are the arguments?
What are the parameters?

Answer 20

X and y
A and b