Java 1 Vocabulary
Pixels: Tiny dots on the computer screen.
Object: An instance of a class.
Class: Provide methods and fields for objects.
Method: Verb à Tells us the behaviors of
an object.
Fields: Adjective à The “state” of an object.
Statement: A command followed
by a semi-colon.
Command: Calling an object’s method.
Comment: A message for the human reader of the program.
Types
of Comments
// insert comment here
/* YOU CAN
WRITE HERE AS A COMMENT
these are comments
on several lines
*/ THIS WOULD NOT BE A COMMENT
/**
* This is a “Java Doc”
comment.
*
*/
Braces: {
} à Used to define the scope of a class or
method.
Main
Method: Driver of the program. When you
have a main method, you have an “application program”
Vocabulary
from
Method
definition: public void
(instead of public one might write
private)
(instead of void, one might write “int”,
“String”)
Public: It can be referred to by any other class.
Void: The method returns NOTHING.
Instance: An object of a class.
Executor: The object that’s calling the method.
Example: sam.fillBox(40,
40);
The executor is: sam
++++++++
We
already have the Turtle class and it has six methods.
We
want to improve the Turtle class à SPECIALIZATION
(SmartTurtle)
Super
class: Turtle
Sub
class: SmartTurtle
Inherit: The SmartTurtle is capable of doing
everything a Turtle can do. (Has the use
of all Turtle methods.)
Header for the SmartTurtle
Public class SmartTurtle extends Turtle
Vocabulary
for Class #13 |
Identifier: Name
WE CHOOSE for a method, variable, or class.
Keyword: PART OF THE JAVA PROGRAMMING LANGUAGE with a specific use/for a
specific purpose.
You can never use a KEYWORD as an identifier.
Titlecase: Only capitalizing the first letter of each word in an identifier,
EXCEPT FOR THE FIRST WORD.
For
example: move(), switchTo(), drawFiveSidedStar()
THE ONE EXCEPTION: Class name ALWAYS begins
with a capital letter.
Compiler: Converts
the SOURCE CODE (what we type) into bytecode.
Bytecode: The
code the Java Virtual Machine uses to run the program.
Java Virtual Machine (JVM)
This INTERPRETS the bytecode!
Interprets
Converts it to machine code AND RUNS IT.
Method Call: executor.methodName();
Method Header: public returnType methodName(type param1, type param2)
Boolean: Either true or false.
Robust: Fail-proof. Uses if
statements to ensure that procedures can be carried out.
Condition: Either true or false. Is
evaluated inside of an if statement.
Overload: When two or more methods have the same name with either:
a) different number of
parameters
b) different type for the
parameters
Precondition: What has to be true when a method begins execution, in order for the
method to produce the expected result.
“!”
(not) operator: This will return the
OPPOSITE value of what is being evaluated.
For example, if a slot is filled, the call to seesSlot() will return
TRUE! But if you write !seesSlot() à returns FALSE!
Return Statement: A return statement is the word “return” followed by a value or
expression (condition) that is of the return type of the method. You can have multiple return statements in a
method. The method ends when it
encounters its first return statement.
If you want to exit a VOID method early, you can write “return;”
Boolean Method: A method that returns
either true or false.
Class
#28 –
Action Method: DO NOT return anything. They do, however, change the state of an
object.
Examples: sam.moveOn(),
sue.putCD()
Query Method: DO return something. However, they should maintain state. Boolean methods are typically “query”
methods.
Assign: To “assign” means to give a variable
a value. This is done using the “=”
sign.
Variable: Is of a specific “type” (ex. int,
double, string, boolean, etc.) These are
used within classes and methods.
Boolean
Variables: A variable that is of the
“boolean” type and therefore can only be equal to “true” or “false”.
Class
#29 –
Boolean Operators
“!” (not) à Means “opposite”. Takes one operand.
“&&” (AND) à Takes two operands; will only evaluate to
true if they are BOTH TRUE.
Ex. a && b , seesSlot()
&& seesCD()
“||” (OR) à Takes two operands; will evaluate to true so
long as at least ONE operand is true.
Ex. a || b , seesCD() || stackHasCD()
Short Circuit: The second operand of an && or ||
expression is not evaluated if the first operand BY ITSELF determines its truth
or falseness.