Finals Notes III

Question 1

void change(int[] x, int[] y) {
int[] temp = x;
x = y;
y = temp;
x[0] = 99;
}
int[] a = {1, 2, 3};
int[] b = {4, 5, 6};
change(a, b);

Why does this not change?

Answer 1

The copies of the REFERENCES are being swapped.
The original values stay the same.

Question 2

What is an object? What does it store?

Answer 2

• Specific instance of a class
• Has a state (data) and behavior (actions)

Question 3

What are the parts of declaring a class?

Answer 3

Instance variables, constructors, and methods.

Question 4

What are methods?

Answer 4

Getters, setters, etc.

Question 5

What is inheritance?

Answer 5

A child class inherits states and behaviors from the parent

Question 6

How do you create a SuperArray object?

Answer 6

SuperArray name = new SuperArray()

Question 7

How do you add something to a SuperArray?

Answer 7

name.add(“thing”)

Question 8

What does print do for a SuperArray?

Answer 8

Prints out everything but null elements.

Question 9

If nothing is given for an index in a SuperArray, what is automatically placed at that index?

Answer 9

null

Question 10

What is the code for catching an exception?

Answer 10

try { //block of code }
catch { //code executed when exception happens}
finally { //optional }

Question 11

How do you print out the stack trace?

Answer 11

e.printStackTrace();

Question 12

What is the variable name commonly placed with an exception while catching?

Answer 12

e

Question 13

How do you throw an exception?

Answer 13

throw new NameOfException (“Message”)

Question 14

What are some examples of wrapper classes?

Answer 14

Boolean, Character, Integer, Double

Question 15

How can you simplify this statement?
Integer y = Integer.valueOf(3);

Answer 15

Integer myInt = 3;

Question 16

How do you declare an ArrayList?

Answer 16

ArrayList< Type > name = new ArrayList< Type >();

Question 17

How do you import the ArrayList class?

Answer 17

import java.util.ArrayList;

Question 18

When do you use an ArrayList over an Array?

Answer 18

You do not know how many items you need.
You want to remove or add items to the list.