1. Concepts From Alice
Switching to Java
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2. Concepts We Have Seen Concepts
Objects
Looping statements
Blocks
Concurrency
Variables
Bugs
We should have seen the equivalent Java code for Alice statements
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3. The Process Programming is bossing the machine around
Making it do what you want
When it does not do what you intended it is a bug
A program is a sequence of statements that accomplish this
There are many little details that must be right for good results
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4. Objects A self contained piece of code Methods, properties, events
An object may be composed of smaller objects
We may do things to the larger object
We may also do things to the contained objects
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5. More on Objects Alice objects are obtained from gallery
We may drag in an object more than once
In Java we have classes and objects
An object being an instance of a class
The Java library is much larger than the Alice gallery
Often we specify the portion of the library that contains the class we need
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6. Variables An item that may contain a value Two kinds in Java
Primitive types contain simple things like an integer or character
Similar to Alice parameter values
Objects
Contains values and methods
Values may be primitive or other objects
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7. Decision statements
Java decision statements are actually easier to create than those of Alice
Type rather than drag and drop
Two types of decision If
Similar to Alice
Based on boolean
Switch case
Multi-way decision
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8. Looping statements
There are three loops in Java compared to two in Alice
The for is the counting loop
Most similar to the Loop of Alice
The while of Java is similar to the Alice while
The do of Java is a trailing decision loop
There are no trailing decision loops in Alice
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9. Blocks
The statements of a Do Together, Do In Order, If, Loop etc. form a block
A block is a container that holds one or more statements
Bundles these together as one
The Java block is just a pair of braces { }
It is stronger than that of Alice
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10. Concurrency Java handles concurrency very well for a language
It is not nearly as easy to use as in Alice
It is unlikely that we will cover in this class
The important terms in Java are:
thread
runnable interface
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11. Event Handling
An event is some action that occurs at an unpredictable time
A user types a key
Event handling is the action that a program does in response to the event
We will likely see event handling in regards to a user clicking a button in Java
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12. Environment
In early programming languages the entire program was typed
Today we usually use a combination
Drag and drop
Used to design the window
Initialize event handling
Typing
Enter the central logic of the program
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13. Java Environment There are many, some are even free
We will use Eclipse Java SE
You should download this soon
Even as you are still working on the Alice program
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14. Finally This concludes our short detour through Alice
Alice shows all the features of a general purpose language
Since you are able to create Alice programs you are also able to create Java programs
Even if it is not quite as fun or easy
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