Is it possible to create an array in Java where the first row has 5 elements, the second row has 6
elements and the third row has 2 elements? - Answers yes
create a for loop to execute: Is it possible to create an array in Java where the first row has 5 elements,
the second row has 6 elements and the third row has 2 elements? - Answers double [] [] salaries = new
double [NUM_STORES][];
array[0] = new double [5];
array[1] = new double [6];
array[2] = new double [2];
Write the statement to print the number of elements in a one-dimensional array. - Answers for(i =0;
i<array.length -1; i++)
{
System.out.println(array[i]);
}
What does Java initialize the elements of an array of references to? - Answers null
What does Java initialize an array of ints to? - Answers 0
Is an array an object? - Answers Yes
int [ ] numbers = new int[16] how many objects were created? - Answers 1, new was used once
Student [ ] roster = new Student[25] <- how many objects were created? - Answers 1, new was used
once
Write the command to compile a source code file named Book.java - Answers javac Book.java
Write the command to run a class file named Book.class - Answers java Book
Where does the execution of a Java project begin? - Answers public static void main(String [] args)
How many public classes can a Java class file contain? - Answers 1
Can you declare fields of a class inside a method? - Answers No
What does private access for a field mean? - Answers Only the current class will have access to the field
or method.
What does public access for a field mean? - Answers Any class can refer to the field or call the method.
, What does protected access for a field mean? - Answers Only the current class and sub classes (and
sometimes also same-package classes) of this class will have access to the field or method.
What happens if you do not specify the access for a field? - Answers It will set the access to package
Can a sub-class also be a super-class? - Answers Yes, Java allows this
What is an abstract method? - Answers It is a method that is declared, but contains no implementation
What is an abstract class? - Answers Is a class that is declared abstract —it may or may not include
abstract methods. Abstract classes cannot be instantiated, but they can be sub classed.
Does a super class have to be abstract? - Answers No
How many classes can a class directly inherit from? - Answers 1
How many interfaces can a class implement? - Answers Multiple or unlimited
What can a Java interface contain? - Answers Consists of modifiers, the keyword interface, the interface
name, a comma-separated list of parent interfaces (if any), and the interface body
Can an interface be instantiated? - Answers You can never instantiate an interface in java.
Does the is-a relationship apply to classes that implement an interface? - Answers No
What is the difference between overloading a method and overriding a method? - Answers Overloading:
is the ability to create multiple methods of the same name with different implementations.
Overriding: is a language feature that allows a subclass or child class to provide a specific
implementation of a method that is already provided by one of its superclasses or parent classes.
What class does every class indirectly inherit from? - Answers Object class
What is a method every class has whether you write it or not? - Answers object.equals() method
What causes a null-pointer exception? - Answers is thrown when an application attempts to use an
object reference, having the null value.
What is the purpose of the dot operator? - Answers It allows one to invoke a method within an object
when given a reference to the object
What is meant by encapsulation? - Answers is a mechanism of wrapping the data (variables) and code
acting on the data (methods) together as as single unit.
What type of Exceptions require the programmer to acknowledge? - Answers Checked Exceptions