APCSA Chapter 5 & 6 Questions

What symbol will you use to concatenate two string values?

+ (plus sign)

How many JetPlane objects are created when the statement below are run? JetPlane ref1 = new JetPlane(); JetPlane ref2 = ref1;

1

If a JetPlane class has defined an integer property named "maxSpeed", how many unique copies of that property are made after the statements below run? JetPlane myRide = new JetPlane(); JetPlane yourRide = new JetPlane(); JetPlane theirRide = new JetPlane();

3

Given the code below, what value is stored in the result variable? String surprise = "quiz"; int result = surprise.length();

4

Given the following constructor signature, what types of data must be provided and in what order? public JetPlane(String nickname, double cost, int speed)

A String, a double, and an int, in that order

Which answer best describes the relationship between the terms "class" and "object"?

An object is a copy of a class that is created in a running program

Which of the following two lines will successfully initialize a String variable with the text "I'm Alive!"? String text1 = new String("I'm Alive!"); String text2 = "I'm Alive!";

Both will work

If you call the Scanner's nextInt() method, then the nextLine() method, what should you do in-between to ensure your program gets the expected user data?

Call nextLine() to flush the newline character left behind by nextInt()

What does the result variable contain after the following statement? String result = "Captain," + "incoming" + "message";

Captain,incomingmessage

What term is used to describe a method that runs automatically when an object is created to help initialize the object properties?

Constructor

A class is generally defined by what three main features?

Data, behavior, and relationships

What must a class do to "overload" a method?

Define multiple versions of the method with the same name but different parameters

What does the result variable contain after the following statement? String result = String.format("I'll take %5s please", "2");

I'll take 2 please

What part of the Java platform contains a large library of pre-written classes that you can use?

Java Class Library

Which of the following lines will create a new object of type "JetPlane" and store it in a reference variable?

JetPlane myRide = new JetPlane();

If the JetPlane class constructor requires an int value and String value to initialize an object, how would you provide those values?

JetPlane myRide = new JetPlane(1000, "Gulfstream");

What part of a class is used to define the behavior?

Methods

What does the term OOP mean?

Object-Oriented Programming

What term is used to describe an organized set of Java classes?

Package

Given the code below, what value is stored in the result variable? String surprise = "Quiz"; String result = surprise.toUpperCase();

QUIZ

What is a big difference between reference data types and primitive data types?

References point to more complex objects somewhere in memory, while each primitive value contains a copy of some simple data

Assuming a Scanner has been initialized in the "input" variable, which of the following statements will read an entire line of text from the user?

String text = input.nextLine();

What three things can you tell from any method signature?

The method's name, required input parameters, and return data type

What is the purpose of the ASCII and Unicode systems?

To represent individual characters with unique numbers

What does the result variable contain after the following statement? String result = String.format("%.3s", "abcdef");

abc

Given the method signature below, what is the method's return data type? boolean takeOff(int maxSpeed, double currentWindSpeed)

boolean

Given the method call below, which of the following answers is most likely method signature for the "takeOff" method? boolean isAirborne = myRide.takeoff(25.5);

boolean takeOff(double windSpeed)

Given the code below, what value is stored in the result variable? String surprise = "quiz"; boolean result = surprise.contains("Q");

false

Given the following code, what will be the value stored in the result and why? String color1 = "RED"; String color2 = "red"; boolean result = color1.equals(color2);

false, because while the letters in each value match, the capitalization is different

What does the result variable contain after the following statement? String result = String.format("humpty %2$s", "humpty", "dumpty");

humpty dumpty

What does the result variable contain after the following statement? String result = String.format("humpty dumpty", "sat", "on", "a", "wall");

humpty dumpty

Which statement can be placed at the top of your source code for easy access to the Scanner class?

import java.util.*;

If the "getMaxSpeed" method returns an int and is defined as "static" on the JetPlane class, which of the following statements would successfully call that method?

int max = JetPlane.getMaxSpeed();

If a JetPlane class has defined an integer property named "maxSpeed", given the code below, which statement would successfully assign a value to the property? JetPlane myRide = new JetPlane();

myRide.maxSpeed = 1000;

Which Scanner method would you call to read in the next user entry and automatically convert it to a "double" value?

nextDouble()

Given the code below, without knowing the exact contents of the strings, what can always be said about result1 and result2? String s1 = ... String s2 = ... boolean result1 = s1.equals(s2); boolean result2 = s2.equals(s1);

result1 and result2 will have the same value

Given the following code, what will be the value stored in the result and why? String color1 = "RED"; String COLOR2 = "red"; boolean result = color1.equalsIgnoreCase(COLOR2);

true, because the equalsIgnoreCase() method ignores capitalization and just compares the letters

Given the following code, what will be the value stored in the result and why? String color1 = "red"; String color2 = "red"; boolean result = color1.equals(color2);

true, because the two string values have exactly the same characters and capitalization

Given the code below, what value is stored in the result variable? String surprise = "quiz"; String result = surprise.substring(1,4);

uiz

Given the code below, what value is stored in the result variable? String surprise = "quiz"; char result = surprise.charAt(3);

z