Exam 3: Object-Oriented Programming, Part 1: Using Classes

What is the value of the expression Math.sqrt( 4 )?

In which package is the class DecimalFormat?

The accessors are the get methods.

When writing code, you can include two forward slashes for a comment and then later replace them with back slashes to uncomment.

What is the output of this code sequence? String word = "Java"; System.out.println( word.length( ) );

Wrapper classes define an instance variable of a primitive data type and provide useful methods for converting the primitive data types into objects.

Why do you think the String class is in the java.lang package?

Which keyword allows you to use a Java class inside a program?

In what package is the class Scanner?

Write a Java statement to import the DecimalFormat class from the appropriate package.

When an object reference is first declared, its value is null.

Java would generate a compiler error and a run-time error if you attempt to call a method using an object reference whose value is null.

What is the value of the expression Math.pow( 3, 2 )?

By convention, method names, instance variables, and object names start with a lowercase letter.

The automatic conversion from a primitive numeric type to its wrapper class is called:

The automatic conversion from a numeric wrapper class to the corresponding primitive numeric type is called:

What is the output of this code sequence? String word = "Java"; System.out.println( word.charAt( 1 ) );

The first index of a String is 1.

Which methods of the String class would you use to retrieve the user name from an email address whose format is username@provider?

String is in the java.string package.