Chapter 3
Core Java APIs

OCA exam objectives covered in this chapter:

• Using Operators and Decision Constructs
  • Test equality between Strings and other objects using == and equals()
• Creating and Using Arrays
  • Declare, instantiate, initialize and use a one-dimensional array
  • Declare, instantiate, initialize and use a multi-dimensional array
• Working with Selected classes from the Java API
  • Creating and manipulating Strings
  • Manipulate data using the StringBuilder class and its methods
  • Declare and use an ArrayList of a given type
  • Create and manipulate calendar data using classes from java.time.LocalDateTime, java.time.LocalDate, java.time.LocalTime, java.time.format.DateTimeFormatter, java.time.Period
• Working with Java Data Types
  • Develop code that uses wrapper classes such as Boolean, Double, and Integer.

The OCA exam expects you to know the core data structures and classes used in Java, and in this chapter readers will learn about the most common methods available. For example...