Test 2 Prep 2 Questions

Question 1

All Java classes have a default constructor

Answer 1

False

Question 2

The following instantiates an array of ints:

int [ ] array;

Answer 2

False

Question 3

The following declares an array of doubles:

double [ ] array;

Answer 3

True

Question 4

In the following code, num is a reference type:

int num = 3;

Answer 4

False

Question 5

In the following code, array is a reference type:

int [ ] array;

Answer 5

True

Question 6

In the following code, array is a reference type:

Integer [ ] array;

Answer 6

True

Question 7

In the following code, name is a primitive type:

String name = “marc”;

Answer 7

False

Question 8

Will the following compile:
ArrayList array = new ArrayList(10);

Answer 8

True

Question 9

The following code will compile:

Integer num = 4;

Answer 9

True

Question 10

What (true or false) will the following method return when run:
public boolean method() {
    String str1 = new String("OOP");
    String str2 = new String("OOP");
    return str1 == str2;
}

Answer 10

False

Question 11

The following will compile: 
ArrayList array = new List();

Answer 11

False

Question 12

The following will compile:
ArrayList list = new ArrayList();
list.add(“Marc was here”);
System.out.println(list.get(0).toUpperCase());

Answer 12

False

Question 13

Given the following code:
public class Chef {
private String name;
private int noodles;

    public Chef(String name, int noodles) {
        this.name = name;
        this.noodles = noodles;
    }

    public Chef(String name) {
        this.name = name;
        this(name, 20);
    }

    public String toString() {
        return this.name + " : "  + this.noodles;
    }
}
... in another file ...
public static void main(String[] args) {
    Chef marc = new Chef("Marc", 50);
    System.out.println(marc);
}

What will happen when the code is run?

a. ) “Chef@[Some hexadecimal numbers]” will be printed
b. ) “Marc : 50” will be printed
c. ) Some runtime error
d. ) Some compile-time error

Answer 13

d.)

Question 14

Given some classes and interfaces with following partial declarations:

public abstract class Animal;
public class Snake extends Animal;
public interface Mammal;
public Whale implements Mammal;
public class Tiger extends Animal;

Which of the following (zero or more) will cause a compilation error (assuming all constructors exist):

a. ) Animal steve = new Snake();
b. ) Animal unknownSpecies = new Mammal();
c. ) Mammal sean = new Whale();
d. ) Mammal mike = new Tiger();
e. ) Animal jim = new Animal();

Answer 14

b.), d.), and e.)

Question 15

Given the following code:

ArrayList list = new ArrayList(10);

list. add(“Marc”);
list. add(“Chris”);
list. add(Harsh”);
list. remove(“Chris”);

What will list.length return?

a. ) 10
b. ) 3
c. ) 2
d. ) None of the above / other answer

Answer 15

d.)

Question 16

What is a method signature?

Answer 16

A method’s signature is comprised of the method’s name and the method’s input parameters.

Question 17

In your own words, explain and give an example of overloading

Answer 17

The Java programming language supports overloading methods, and Java can distinguish between methods with different method signatures. This means that methods within a class can have the same name if they have different parameter lists.

ex)
cook (int rice);
cook (int rice, int beans);
cook (int rice, int beans, int lettuce);