Computer Science 100

Computational Expression

Gregory M. Kapfhammer

Color Scheme

Key Concept

Corresponding Diagram

In-Class Discussion

In-Class Activity

Details in the Textbook

Computer Graphics

Displaying pixels on the screen

Using a coordinate system

Representing color with RGB values

Try to use the showrgb command in the terminal!

Can you connect the RGB values to a specific color?


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Let's Try It!

Run git pull download master in your "inclass" repository

Follow the instructions in the source code to run the program

What is the output of this program?

How does this program create graphical output?

Where do you see pixels on the screen?

Write two sentences to describe the output

Remember to transfer your source code to GitHub!

Use shapes to make it easier to display graphics

Use the JavaFX package

Any questions about computer graphics?

See Section 3.9 for more details

Objects and Primitives

Similarities and differences?

Can you create a list for both of these?

What does this look like in memory?

Aliases for reference variables

Refer to Section 3.1 for more details and diagrams!

String Manipulation

Real world examples of string processing?

Purpose of and ways to index a string?

See Figure 3.1 for the methods provided by String


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Let's Try It!

String "mutations" change the content of strings

git pull download master

Finish the program from Listing 3.1 on page 106

Ensure that the program produces the correct output

Can you explain the output of this program?

Packages

What is a class library?

Application programming interface (API)

What are some examples of packages?

Check the online documentation!

Make sure to use an import!

Let's explore a new package!

Random Numbers

Provided by java.util.Random

Calculations based on a seed value

Study the source code in Listing 3.2

Will the program always produce this output?

See Figure 3.4 for examples of Random methods


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Formatting Output

What do you do if the output needs a special format?

The DecimalFormat and NumberFormat classes

You can format correct for currency and percentages!

See details in the text — may help on an assignment!

Enumerated Types

What to do if a variable only has a few possible "types"?

For instance, a letter grade has distinct values

Or, across the world, seasons have categories

You can use enumerated types to define these categories

See details in the text — may help on an assignment!