Decimal vs Binary
Here are some equivalent values:
Try the following exercises:
2 Methods for binary-decimal conversions
Hexadecimal Number System
Octal Number System
More help
Octal to Hexadecimal conversion
Check edmodo.com for exercises.
Classwork:
Standard Drawing: Animation
Discussion on BouncingBall.java and Banner.java
Check on edmodo.com for assignment: CrossingBalls.java
Homework:
Check on edmodo.com for assignment: SongLyrics.java
Standard Drawing: Animation and images
Images. PU standard draw library supports drawing pictures as well as geometric shapes.
https://introcs.cs.princeton.edu/java/15inout/TennisBall.png https://introcs.cs.princeton.edu/java/15inout/pipebang.wav
- A first example. MouseFollower.java is the HelloWorld of mouse interaction. It draws a blue ball, centered on the location of the mouse. When the user holds down the mouse button, the ball changes color from blue to cyan. A simple attractor. OneSimpleAttractor.java simulates the motion of a blue ball that is attracted to the mouse. It also accounts for a drag force.
- Many simple attractors. SimpleAttractors.java simulates the motion of 20 blue balls that are attracted to the mouse. It also accounts for a drag force. When the user clicks, the balls disperse randomly.
- Springs. Springs.java implements a spring system.
Standard audio.
StdAudio is a library that you can use to play and manipulate sound files. It allows you to play, manipulate and synthesize sound.
We introduce some some basic concepts behind one of the oldest and most important areas of computer science and scientific computing: digital signal processing.
- Concert A. Concert A is a sine wave, scaled to oscillate at a frequency of 440 times per second. The function sin(t) repeats itself once every 2π units on the x-axis, so if we measure t in seconds and plot the function sin(2πt × 440) we get a curve that oscillates 440 times per second. The amplitude (y-value) corresponds to the volume. We assume it is scaled to be between −1 and +1.
- Other notes. A simple mathematical formula characterizes the other notes on the chromatic scale. They are divided equally on a logarithmic (base 2) scale: there are twelve notes on the chromatic scale, and we get the ith note above a given note by multiplying its frequency by the (i/12)th power of 2.
- When you double or halve the frequency, you move up or down an octave on the scale. For example 880 hertz is one octave above concert A and 110 hertz is two octaves below concert A.
- Sampling. For digital sound, we represent a curve by sampling it at regular intervals, in precisely the same manner as when we plot function graphs. We sample sufficiently often that we have an accurate representation of the curve—a widely used sampling rate is 44,100 samples per second. It is that simple: we represent sound as an array of numbers (real numbers that are between −1 and +1).
For example, the following code fragment plays concert A for 10 seconds.
int SAMPLING_RATE = 44100; double hz = 440.0; double duration = 10.0; int n = (int) (SAMPLING_RATE * duration); double[] a = new double[n+1]; for (int i = 0; i <= n; i++) { a[i] = Math.sin(2 * Math.PI * i * hz / SAMPLING_RATE); } StdAudio.play(a);
- Play that tune. PlayThatTune.java is an example that shows how easily we can create music with StdAudio. It takes notes from standard input, indexed on the chromatic scale from concert A, and plays them on standard audio.
Your first animation using java!!!
Standard Drawing: Animation and images Images.
/******************************************************************************
* Compilation: javac BouncingBall.java
* Execution: java BouncingBall
* Dependencies: StdDraw.java
*
* Implementation of a 2-d bouncing ball in the box from (-1, -1) to (1, 1).
*
* % java BouncingBall
*
******************************************************************************/
public class BouncingBall {
public static void main(String[] args) {
// set the scale of the coordinate system
StdDraw.setXscale(-1.0, 1.0);
StdDraw.setYscale(-1.0, 1.0);
StdDraw.enableDoubleBuffering();
// initial values
double rx = 0.480, ry = 0.860; // position
double vx = 0.015, vy = 0.023; // velocity
double radius = 0.05; // radius
// main animation loop
while (true) {
// bounce off wall according to law of elastic collision
if (Math.abs(rx + vx) > 1.0 - radius) vx = -vx;
if (Math.abs(ry + vy) > 1.0 - radius) vy = -vy;
// update position
rx = rx + vx;
ry = ry + vy;
// clear the background
StdDraw.clear(StdDraw.GRAY);
// draw ball on the screen
StdDraw.setPenColor(StdDraw.BLACK);
StdDraw.filledCircle(rx, ry, radius);
// copy offscreen buffer to onscreen
StdDraw.show();
// pause for 20 ms
StdDraw.pause(20);
}
}
}
Copyright © 2000–2011, Robert Sedgewick and Kevin Wayne.
Last updated: Tue Aug 30 09:58:33 EDT 2016.
Classwork:
Add this program to your current project.
Make the following changes, submit a screenshot for each change and the final program:
Reminder:
Classwork:
Write a program, BarGraph2_YI.java to create a bar graph with asterisks as in the previous bar graph. However, the array’s values are the raw data. Use this array and values, dataSet = { 67, 89, 55, 100, 95, 93, 57, 19, 88, 87, 86, 91,90}.
Output: 00-09: 10-19: * 20-29: 30-39: 40-49: 50-59: ** 60-69: * 70-79: 80-89: **** 90-99: **** 100: *
Do not use if statements to check if the value fall within a range.
HINT: What is the result of dividing each grade by 10?
WARNING: DO NOT USE if STATEMENTS!!! or WHILE LOOPS TO FIND THE RANGE OF THE GRADES!!!
Claswork/Homework:
Consider the following:
Twenty students were asked to rate on a scale of 1 to 5 the quality of the food in the student cafeteria, with 1 being “awful” and 5 being “excellent.” Randomly assign 20 responses to an integer array and determine the frequency of each rating.
Using what you learned about the elements of an array as counters, write a program, FoodSurvey_YI.java to display the rating and their frequency in two well formatted columns.
Output example:
Rating Frequency 1: 10 2: 5 3: 2 4: 2 5: 1
Additional programming style guidelines:
/* * 1. Make sure your program has indentation when is needed. * 2. Please include a comment line about local variables and group them all * together at the top of the program as long as it is not an OOD program. * 3. Never create a new local variable inside a loop! * 4. Have a blank line between different parts of the program */
final int COUNTRIES = 7; final int MEDALS = 3; int[][] counts = new int[COUNTRIES][MEDALS];
or but not both:
int[][] counts = {
{ 1, 0, 1 },
{ 1, 1, 0 },
{ 0, 0, 1 },
{ 1, 0, 0 },
{ 0, 1, 1 },
{ 0, 1, 1 },
{ 1, 1, 0 }
};
for (int i = 0; i < COUNTRIES; i++)
{
// Process the ith row
for (int j = 0; j < MEDALS; j++)
{
// Process the jth column in the ith row
System.out.printf("%8d", counts[i][j]);
}
System.out.println(); // Start a new line at the end of the row
}
for (int i = 0; i < counts.length; i++)
{
for (int j = 0; j < counts[0].length; j++)
{
System.out.printf("%8d", counts[i][j]);
}
System.out.println();
}
Accessing the neighboring elements of a 2D array
Adding by rows:
int total = 0;
for (int i = 0; i < COUNTRIES; i++)
{
total = 0;
for (int j = 0; j < MEDALS; j++)
{
total = total + counts[i][j];
}
}
Adding by columns:
int total = 0;
for (int j = 0; j < MEDALS; j++)
{
total = 0;
for (int i = 0; i < COUNTRIES; i++)
{
total = total + counts[i][j];
}
}
Classwork:
Write a program, MedalsTable_YI.java to produce the following output:
Assignment:
Consider as an example an 8 × 8 array for a board game:
int[][] board = new int[8][8];
BoardGame_YI.java: Using two nested loops, initialize the board using "for" loops so that zeroes and ones alternate, as on a checkerboard. Prompt the user for the size of the "square" 2D array and display the board on the screen.
0 1 0 1 0 1 0 1 1 0 1 0 1 0 1 0 0 1 0 1 0 1 0 1 ... 1 0 1 0 1 0 1 0
Hint: Check whether i + j is even.
Write a program Minesweeper_YI.java that takes 3 input arguments m, n, and p and produces an m-by-n boolean array where each entry is occupied with probability p. In the minesweeper game, occupied cells represent bombs and empty cells represent safe cells. Print the array using an asterisk for bombs and a period for safe cells. Then, replace each safe square with the number of neighboring bombs (above, below, left, right, or diagonal) and print the solution.
HS-TEACHER-17464:Array2D gracielaelia$ java Minesweeper 3 3 0.2 . . . . . . * . . 0 0 0 1 1 0 * 1 0
Try to write your code so that you have as few special cases as possible to deal with, by using an (m+2)-by-(n+2) boolean array.
HS-TEACHER-17464:Array2D gracielaelia$ java Minesweeper 3 3 0.3 . . * . . * . . * 0 2 * 0 3 * 0 2 * HS-TEACHER-17464:Array2D gracielaelia$ java Minesweeper 3 3 0.4 . . . * . . . . . 1 1 0 * 1 0 1 1 0 HS-TEACHER-17464:Array2D gracielaelia$ java Minesweeper 3 3 0.5 * * * . * * * . * * * * 4 * * * 4 * HS-TEACHER-17464:Array2D gracielaelia$ java Minesweeper 3 3 0.6 * * * . . * * * * * * * 4 7 * * * * HS-TEACHER-17464:Array2D gracielaelia$ java Minesweeper 3 3 0.7 . * * * * * * . * 3 * * * * * * 5 * HS-TEACHER-17464:Array2D gracielaelia$ java Minesweeper 3 3 0.8 * . * * * . * * * * 4 * * * 4 * * * HS-TEACHER-17464:Array2D gracielaelia$ java Minesweeper 3 3 0.9 * * * * * . * * * * * * * * 5 * * *
Required Submission:
Submit the file with the ‘”java” extension.
3. Make sure you document code snippets that have a particular purpose!
4. Testing: Have multiple boards with different board sizes and different probabilities. The minimum should be 3 boards.
Game Of Life:
If you have successfully completed the random block program and written the draft for the algorithm in pseudocode, you should be able to get started with the game of life assignment.
Start small. Hardcode the seed for the glider:
Requirements:
1. Take as input the size of the grid.
2. Show the live cells in color other than black.
Challenges:
1. Take as input the coordinates for the seed. You must include in your documentation the coordinates for the glider seed.
2. Change the color of the dead cells to a faded color for at least one generation after dying.
3. Take as input the option to speed or slow down the simulation.
Classwork/Homework:
(Game: connect four) Connect four is a two-player board game in which the players alternately drop colored disks into a seven-column, six-row vertically suspended grid, as shown below.
The objective of the game is to connect four same-colored disks in a row, a column, or a diagonal before your opponent can do likewise. The program prompts two players to drop a red or yellow disk alternately. In the preceding figure, the red disk is shown in a dark color and the yellow in a light color. Whenever a disk is dropped, the program redisplays the board on the console and determines the status of the game (win, draw, or continue). Here is a sample run:
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ——————————————— Drop a red disk at column (0–6): 0 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |R| | | | | | | ——————————————— Drop a yellow disk at column (0–6): 4 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |R| | | |Y| | | . . . . Drop a yellow disk at column (0–6): 6 | | | | | | | | | | | | | | | | | | | | |Y| | | | | | |Y|Y|Y|R| | | |Y|R|R|Y|Y| |R|Y|R|Y|R|R|R| ——————————————— The yellow player won Do you want to play again?
Write the two-player program, YI_Connect4.java. Display at a every move the board as shown in the example above. Include a prompt to continue playing.
Your program should include:
1. Good documentation
2. An introduction message
3. Functions (Optional)
4. An end of game message
5. Input/output
What is good documentation?
Answer:
Nothing like good pseudocode!!
One more
