A Java 8 Primer: An Introduction to Java 8 Concepts and Principles - Beginning Java 8 Games Development - page 93

boolean travelingWest = false ; // Create boolean
variable travelingWest, initialize to false
hitLeftSideScrn = (invinciBagelX <= 0) ; // boolean
hitLeftSideScrn is TRUE if left side reached
travelingWest = (facingDirection == "W") // boolean
travelingWest is TRUE if facingDirection=" W "
changeDirection = (hitLeftSideScrn && travelingWest) //
Change Direction, if both equate to TRUE
To find out if the InvinciBagel is facing (or traveling, if also moving) West , you
create another travelingWest boolean variable and initialize it (set it equal) to false
(because your initial facingDirection setting is East). Then, you create a boolean vari-
able called hitLeftSideScrn , setting that to the (invinciBagelX <= 0) relational operat-
or statement.
Finally, you create a relational operator statement with the travelingWest =
(facingDirection == "W") logic, and then you are ready to use the
changeDirection boolean variable with your new logical operator. This logical operat-
or will make sure that both the hitLeftSideScrn and travelingWest boolean variables
are set to true , using the changeDirection = (hitLeftSideScrn &&
travelingWest) logical operation programming statement.
Now, you have a little practice declaring and initializing variables and using rela-
tional and logical operators to determine the direction and location of a primary game
piece (called a sprite in arcade games; for more on game design lingo, see Chapter 6 ) .
Next, let's take a look at assignment operators.
Java Assignment Operators
The Java assignment operators assign a value from a logic construct on the right-hand
side of the assignment operator to a variable on the left-hand side of the assignment op-
erator. The most common assignment operator is also the most commonly used operat-
or in the Java programming language, the equals operator . The equals operator can be
prefaced with any of the arithmetic operators to create an assignment operator that also
performs an arithmetic operation, as can be seen in Table 3-5 . This allows a more
“dense” programming statement to be created when the variable itself is going to be
part of the equation. Thus, instead of having to write C = C + A , you can simply use
C+=A and achieve the same end result. You will be using this assignment operator
shortcut often in your game logic design.