To pass an exam of OCA Java Programmer I.

Assume the following:

• Missing package and import statements: If sample code do not include package or import statements, and the question does not explicitly refer to these missing statements, then assume that all sample code is in the same package, and import statements exist to support them.
• No file or directory path names for classes: If a question does not state the file names or directory locations of classes, then assume one of the following, whichever will enable the code to compile and run:
  • All classes are in one file
  • Each class is contained in a separate file, and all files are in one directory
• Unintended line breaks: Sample code might have unintended line breaks. If you see a line of code that looks like it has wrapped, and this creates a situation where the wrapping is significant (for example, a quoted String literal has wrapped), assume that the wrapping is an extension of the same line, and the line does not contain a hard carriage return that would cause a compilation failure.
• Code fragments: A code fragment is a small section of source code that is presented without its context. Assume that all necessary supporting code exists is present and that the supporting environment fully supports the correct compilation and execution of the code shown and its omitted environment.
• Descriptive comments: Take descriptive comments, such as "setter and getters go here," at face value. Assume that correct code exists, compiles, and runs successfully to create the described effect.

TOPICS

Java Basics

• Define the scope of variables
• Define the structure of a Java class
• Create executable Java applications with a main method
• Import other Java packages to make them accessible in your code

Working With Java Data Types

• Declare and initialize variables
• Differentiate between object reference variables and primitive variables
• Read or write to object fields
• Explain an Object's Lifecycle (creation, "dereference" and garbage collection)
• Call methods on objects
• Manipulate data using the StringBuilder class and its methods
• Creating and manipulating Strings

Using Operators and Decision Constructs

• Use Java operators
• Use parenthesis to override operator precedence
• Test equality between Strings and other objects using == and equals ()
• Create if and if/else constructs
• Use a switch statement

Creating and Using Arrays

• Declare, instantiate, initialize and use a one-dimensional array
• Declare, instantiate, initialize and use multi-dimensional array
• Declare and use an ArrayList

Using Loop Constructs

• Create and use while loops
• Create and use for loops including the enhanced for loop
• Create and use do/while loops
• Compare loop constructs
• Use break and continue

Working with Methods and Encapsulation

• Create methods with arguments and return values
• Apply the static keyword to methods and fields
• Create an overloaded method
• Differentiate between default and user defined constructors
• Create and overload constructors
• Apply access modifiers
• Apply encapsulation principles to a class
• Determine the effect upon object references and primitive values when they are passed into methods that change the values

Working with Inheritance

• Implement inheritance
• Develop code that demonstrates the use of polymorphism
• Differentiate between the type of a reference and the type of an object
• Determine when casting is necessary
• Use super and this to access objects and constructors
• Use abstract classes and interfaces

Handling Exceptions

• Differentiate among checked exceptions, RuntimeExceptions and Errors
• Create a try-catch block and determine how exceptions alter normal program flow
• Describe what Exceptions are used for in Java
• Invoke a method that throws an exception
• Recognize common exception classes and categories