JF 2 3

Java Fundamentals
2-3
Procedures and Arguments
Copyright © 2019, Oracle and/or its affiliates. All rights reserved.

Objectives
This lesson covers the following objectives:
• Toggle between, and describe the visual differences
between, the Scene editor and the Code editor
• Locate and describe the purpose of the methods panel
and the procedures tab
• Use procedures to move objects
• Add Java programming procedures to the Code editor
JF 2-3 Copyright © 2019, Oracle and/or its affiliates. All rights reserved. 3
Objectives
This lesson covers the following objectives:
• Demonstrate how procedure values can be altered
• Create programming comments
• Reorder, edit, delete, copy, and disable programming
statements
• Test and debug an animation
Display the Code Editor
• Click Edit Code (from the scene editor) to display the
Code editor.
• The Code editor is where you program your animation.
Select Instance
• First, select the instance
that you want to program.
• This ensures that you are
creating a programming
instruction for the correct
instance.
• Select an instance by
clicking on the instance in
the small scene window or
by using the instance pull
down menu below the
small scene window.
Methods Panel
The Methods Panel
contains two tabs:
• Procedures: All pre-
defined procedures for an
object.
• Functions: All pre-defined
functions for an object.
Procedures Tab
The Procedures tab displays pre-defined procedures for
the selected instance, as well as procedures of your own
that you define.
A procedure is a piece of program

code that defines how the object
should execute a task. Alice 3 has a
set of procedures for each class;
however, users can create
("declare") new procedures.
Functions Tab
The Functions tab displays pre-defined functions for the
selected instance, as well as functions of your own that
you define.
A Function computes and answers a

question about an object, such as,
"What is its width or height?", or
"What is its distance from another
object?" Alice 3 has a set of
functions for each class; however,
users can declare new functions.
Code Editor Tabs
• The Class Menu displays to the left of the Scene tab.
• You create your programming instructions on the
myFirstMethod tab.
• By default, Alice creates a Do In Order control statement
in the myFirstMethod procedure.
• The area labeled drop statement here is the location
onto which you will place programming instructions.
Control Statements
At the bottom of the myFirstMethod tab you will find the
Alice 3 control statements.
Object Movement
• Object movement is egocentric:
– Objects move based on the direction they face.
• An object can move in six directions:
– Up
– Down
– Forward
– Backward
– Right
– Left
Examples of Movement Procedures
Procedure Description
Move Moves the object in any one of its six directions.
Move Toward Moves the object toward another object.
Move Away From Moves the object away from another object.
Moves the object from its current position to the center point
Move To
of the target object.
Moves the object from its current position to the center point
Move and Orient
of the target object and adjusts the object's orientation to
To
match the orientation of the target object.
Halts an object's movement for a certain number of seconds.
Delay Delay can be used to slow down the execution of an
animation.
Creates a call-out bubble with text that makes the object
Say
appear to talk.
Examples of Rotation Procedures
Procedure Description
Rotates an object left, right, forward, or backward on its

center point. Left and right turn on the object's vertical
Turn
axis; forward and backward turn on the object's
horizontal axis.
Rolls an object left or right on its center point using the

Roll
object's horizontal axis.
Create a Programming Instruction
From the Procedures tab, click and drag the desired
procedure into myFirstMethod in the Code editor.
Select and Set Argument Values
• After the programming statement is created, use the
drop-down menus to set the values for each argument.
• To access the argument drop-down menu, click on the
down-pointing triangle to the right of the argument
value.
Execute the Program
• Click the Run button to execute the programming
instructions.
• Run the program frequently to test for the desired
results, and alter the values of the arguments as
necessary.
Arguments
• Arguments are selected
after the procedure is
dropped onto the Code
editor.
• Argument types may
include: An argument is a value that the
– Object procedure uses to complete its
– Direction task. A computer program uses
arguments to tell it how to
– Direction amount implement the procedure.
– Time duration
– Text
Argument Menu
• The argument menu offers default argument values to
select from.
• If none of the defaults are suitable, select the Custom
DecimalNumber… option so that you can specify a more
accurate argument value.
Steps to Edit Arguments
• Next to the argument's value, click the arrow to display
the menu of values.
• Select a new value.
• Use the Custom DecimalNumber… option to specify a
value that differs from the default list of values.
Arguments as Placeholders
• When a procedure is dropped into the Code editor, all
argument values must be specified.
• There will be times that you select an argument value as
a temporary placeholder value that will be replaced
later.
Arguments as Placeholders
• For example, you may want an object to move forward
but you are not sure how far.
• Select a placeholder value of 2 meters, run the
animation, determine that a different value is needed,
and then edit the value.
• You can also specify a placeholder value that you will
replace later with a function or a variable.
Steps to Reorder Programming Statements
• Use "Drag and Drop": Select the handle of the
programming statement.
• Drag the programming statement to its new position.
• Drop the programming statement into its new position
by de-selecting the handle.*
*Note: A green position indicator line will appear to help

you align the programming statement to the desired
position.
Edit Programming Statements
Use the drop-down lists to edit the values of a
programming statement.
Delete Programming Statements
• Right-click programming statements to remove parts of
the statement.
• Or delete the entire statement
Edit and Test the Program
• Run the animation to test it, and edit the code as
necessary.
• It may take several cycles of testing and editing to get
the animation to run as desired.
Debugging and Testing
• Debugging and Testing is the process of running the
animation many times, and adjusting the control
statements, procedures, and arguments after each
execution.
• Save often while debugging your program.
Insert Temporary Programming Statements
to Help with Debugging
• You can insert temporary programming statements into
your code to help with debugging.
• For example:
– Imagine that you have an object that is not moving forward.
• Temporarily enter a Say programming statement to
announce that the object is about to move forward.
Insert Temporary Programming Statements
to Help with Debugging
• Test the program to see whether or not the Say
programming statement executes.
• If the Say statement executes, but the object does not
move, this indicates one type of problem
• If both the Say and Move statements do not execute,
this may indicate another type of problem.
Disabling Programming Statements
• Programming statements can be disabled in the Code
editor.
• Disable programming statements to:
– Help isolate portions of code during testing.
– Help you focus on programming, testing, and debugging a
specific instruction.
Steps to Disable a Programming Statement
• Right-click on the programming statement.
• Unselect "Is Enabled" from the drop-down list.
• The color of the programming statement will change to

gray hash marks to show that it is disabled.
Steps to Re-Enable a Disabled Programming
Statement
• Right-click on the programming statement that has
been disabled.
• Select "Is Enabled" from the drop-down list.
• This re-enables the code and removes the grey lines.
Programming Comments
• Including programming comments in an animation
helps humans understand the flow of the programming.
• Comments:
– Describe the intention of the programming instructions.
– Do not affect the functionality of the program because they are
ignored during its execution.
– Are typically placed above the block of programming
statements that it describes.
– Are often written first, in large programs, as an outline of the
programming instructions.
Steps to Enter Comments in a Program
• Drag and drop the comments tile above a code
segment.
• The comment tile is located at the bottom of the
myFirstMethod.
• Type comments that describe the sequence of actions

in the code segment.
Using Comments to Organize Your Program
• Comments can be an excellent tool for organizing the
development of a program.
• For large programs, create a comment that indicates the
end of the program.
• An "end of program" comment helps to minimize
scrolling when adding programming statements to a
lengthy myFirstMethod.
Terminology
Key terms used in this lesson included:
• Argument
• Code editor
• Comments
• Functions
• Methods panel
• Orientation
• Procedure
Summary
In this lesson, you should have learned how to:
• Toggle between, and describe the visual differences
between, the Scene editor and the Code editor
• Locate and describe the purpose of the methods panel
and the procedures tab
• Use procedures to move objects
• Add Java programming procedures to the Code editor
Summary
In this lesson, you should have learned how to:
• Demonstrate how procedure values can be altered
• Create programming comments
• Reorder, edit, delete, copy, and disable programming
statements
• Test and debug an animation

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Java Fundamentals

Copyright © 2019, Oracle and/or its affiliates. All rights reserved.

A procedure is a piece of program

A Function computes and answers a

Rotates an object left, right, forward, or backward on its

Rolls an object left or right on its center point using the

*Note: A green position indicator line will appear to help

• Or delete the entire statement

• The color of the programming statement will change to

• This re-enables the code and removes the grey lines.

• Type comments that describe the sequence of actions

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