CS1101: Programming Methodology comp.nus.sg/~cs1101x

CS1101: Programming Methodology http://www.comp.nus.edu.sg/~cs1101x/

2What's in store in CS1101?

Java Appreciation

OR

What’s In Store In CS1101?

by Aaron Tan24 July 2009, 10am,

LT16


Exercising Your Choice

CS1101 or

CS1101S


CS1101: Course Description

“This module introduces the

fundamental concepts of programming

from an object-oriented perspective,

and is perceived as the first and

foremost introductory course to

computing.” No prior experience is assumed.


CS1101: Objectives Learning about programming methodology

and principles, using the object-oriented model.

Outcomes:

Know how to solve simple algorithmic problems.

Know how to write good small programs.

JAVA is merely a tool.

This is not a course on just JAVA alone!


CS1101: Your Friendly LecturersMr Tan Tuck Choy, Aaron

Seminar Groups: 1, 3, 9Office: COM1 #[email protected] http://www.comp.nus.edu.sg/~tantc/acad.html

A/P Wynne Hsu

Seminar Group: 2Office: COM1 #[email protected] http://www.comp.nus.edu.sg/~whsu

Mr Chan Wai Kit, Henry

Seminar Group: 4Office: COM1 #[email protected] http://www.comp.nus.edu.sg/~hchia

A/P Lee Mong Li, Janice

Seminar Group: 5Office: COM1 #[email protected] http://www.comp.nus.edu.sg/~leeml

A/P Tan Tiow Seng

Seminar Group: 6Office: AS6 #[email protected] http://www.comp.nus.edu.sg/~tants

Prof. Tan Chew Lim

Seminar Group: 7Office: AS6 #[email protected] http://www.comp.nus.edu.sg/~tancl

A/P Tan Soon Huat, Gary

Seminar Group: 8Office: COM1 #[email protected] http://www.comp.nus.edu.sg/~gtan

Discussion leaders (DLs):

Lead discussion in small discussion groups (DGs)

Will be made known later. Refer to module website (Module Info – Staff)


CS1101: Lecture Groups You will be pre-allocated your seminar group

and discussion group.

All groups cover the SAME syllabus, and have common tests.

Students in all groups are graded together as a whole.


Module Website http://www.comp.nus.edu.sg/~cs1101/


IVLE http://ivle.nus.edu.sg

Watch out for announcements

Participate in the forum


Workload (5 MCs) Lectures:

3 hours/week in a lab setting.

Discussion sessions: 2 hours/week in a lab setting.

Continual assessment: Take-home lab assignments Sit-in lab tests Mid-term test Practical Exam


Skills Set (1/2)

Java constructs

Problem solving

Program


Skills Set (2/2) Java constructs (transferable skills)

Class and objects; types and variables; control constructs (selection, repetition); APIs; arrays; exceptions; applications (searching, sorting).

Problem solving (more transferable skills) Programming methodology (development cycle, top-down

design, modularity); testing and debugging; abstraction.

Others Software tools (editor, compiler, debugger,

CourseMarker); mathematical maturity.


A Java Program (Hello.java)

// Display a message.

public class Hello {

public static void main(String[] args) {

System.out.println("Hello World!! :-D");

}

}

Comments

Class name

Method name

Method body

Output


A Java Program (Welcome.java)

// Author: Aaron Tan// Purpose: Ask for user’s name and display a welcome message.

import java.util.*;

public class Welcome {

public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.print("What is your name? "); String name = scanner.next(); System.out.println("Hi " + name + "."); System.out.println("Welcome to CS1101!\n");

}

}

API package

Creating a Scanner object

Input

An object of class String


Object-Oriented Programming (OOP) The fundamental OOP concept:

An object-oriented program uses objects.

Demo on BlueJ: Illustrate concepts of object and class Creation of objects Sending messages to objects


Objects and classes Object-oriented language

Models real-world objects you find in everyday life.

Objects Represent ‘things’ from the real world, or from some problem

domain (“that red 1200cc Honda car”, “my 2-year old Persian cat with a short tail”).

Have name, state (set of values for its attributes) and behaviors (via methods).

Perform actions or interact by sending messages.

Classes Represent all objects of a kind (“car”, “cat”). A class is a model/blueprint/prototype for an object. An object

is an ‘instance’ of a class. Many instances (objects) can be created from a single class.


Problem Solving (1/4) Problem Algorithm Program

Task 1: Anagram Text that is formed by rearrangement of

letters. Examples:

Dear = Astronomer = The Eyes = The Morse Code = A Decimal Point =

ReadMoon StarerThey SeeHere Come DotsI’m A Dot In Place


Problem Solving (2/4) Task 2: Maze


Problem Solving (3/4) Task 3: Sudoku


Problem Solving (4/4) Task 4: Mastermind

Sinks: Correct colour, correct position Hits: Correct colour, wrong position

Secret code

Sinks Hits

Guess #1

Guess #2

1 1

1 2

Guess #3 2 2

Guess #4 4 0

Guess #1 1 0

0 1

1 0

1 1

Secret code

Sinks Hits

Guess #2

Guess #3

Guess #4


Think About It This set of slides will be available at

http://www.comp.nus.edu.sg/~cs1101

Administrative and registration issues Indicate your choice on this website

http://ntsa.comp.nus.edu.sg/freshmen/ You will be pre-allocated your seminar group and

discussion group. Nonetheless, do attend the Course Briefing –

important! LT17, 29 July, Wednesday, 9am – 12nn

If you take CS1101, you will get a copy of “This CS1101 Handbook”


This CS1101 Handbook


Have a great time

in School of

Computing!


BlueJ Designed at Monash University, Australia. Runs on top of Sun Microsystems’ Java Development

Kit (JDK). Provides an Integrated Development Environment

(IDE) with editor, compiler and debugger. Simple user interface, easy to use. Do not need to

write complete application. Refer to course website

http://www.comp.nus.edu.sg/~cs1101/ (click on “Resources…” “Online”)

Download BlueJ and its documentation.


BlueJ: Creating objects (1/4) Choose example shapes.

Classes: Square, Circle, Triangle, Canvas.


BlueJ: Creating objects (2/4) Creating a new object

Right click on Circle class and choose new Circle() to create a new Circle object. Circle() is a constructor.



A new Circle object circle1 is created.


BlueJ: Calling methods (1/3) Methods implement the behavior of the objects.

Right click on the circle1 object and select the makeVisible() method.


BlueJ: Calling methods (2/3) Methods implement the behavior of the objects.

Experiment with other methods: makeInvisible(), moveDown(), moveRight().


BlueJ: Calling methods (3/3) Methods with parameters:

changeColor(newcolor), changeSize(newDiameter), moveHorizontal(distance).


BlueJ: State (1/2) State: the set of values of all the attributes of an

object.

Right click on the circle1 object and select the Inspect function.


BlueJ: State (2/2) Objects of the same class have the same

fields/attributes. But each object may have it own set of values for its attributes.

State of circle1 object.

Fields:int diameterint xPositionint yPositionString Colorboolean isVisible


BlueJ: Source code (1/8) Right click on class Circle and select “Open Editor”.

import java.awt.*;import java.awt.geom.*;/** * A circle that can be manipulated and that draws itself * on a canvas. * @author Michael Kolling and David J. Barnes * @version 1.0 (15 July 2000) */

public class Circle{ private int diameter;

private int xPosition;private int yPosition;private String color;private boolean isVisible;


BlueJ: Source code (2/8) // Create a new circle at default position with default color. public Circle( ) { diameter = 30; xPosition = 20; yPosition = 60; color = "blue"; isVisible = false; }

// Make this circle visible. If it was already visible, do nothing. public void makeVisible( ) { isVisible = true; draw( ); }

// Make this circle invisible. If it was already invisible, do nothing. public void makeInvisible( ) { erase( ); isVisible = false; }


BlueJ: Source code (3/8) // Move the circle a few pixels to the right. public void moveRight( ) { moveHorizontal(20); }

// Move the circle a few pixels to the left. public void moveLeft( ) { moveHorizontal(-20); }

// Move the circle a few pixels up. public void moveUp( ) { moveVertical(-20); }

// Move the circle a few pixels down. public void moveDown( ) { moveVertical(20); }


BlueJ: Source code (4/8) // Move the circle horizontally by 'distance' pixels. public void moveHorizontal(int distance) { erase( ); xPosition += distance; draw( ); }

// Move the circle vertically by 'distance' pixels. public void moveVertical(int distance) { erase( ); yPosition += distance; draw( ); }


BlueJ: Source code (5/8) // Slowly move the circle horizontally by 'distance' pixels. public void slowMoveHorizontal(int distance) { int delta;

if (distance < 0) { delta = -1; distance = -distance; } else { delta = 1; } for (int i = 0; i < distance; i++) { xPosition += delta; draw( ); } }


BlueJ: Source code (6/8) // Slowly move the circle vertically by 'distance' pixels. public void slowMoveVertical(int distance) { int delta;

if (distance < 0) { delta = -1; distance = -distance; } else { delta = 1; } for (int i = 0; i < distance; i++) { yPosition += delta; draw( ); } }


BlueJ: Source code (7/8) // Change the size to the new size (in pixels). // Size must be >= 0. public void changeSize(int newDiameter) { erase( ); diameter = newDiameter; draw( ); }

// Change the color. Valid colors are "red", "yellow", // "blue", "green", "magenta" and "black". public void changeColor(String newColor) { color = newColor; draw( ); }


BlueJ: Source code (8/8) // Draw the circle with current specifications on screen. private void draw( ) { if (isVisible) { Canvas canvas = Canvas.getCanvas( ); canvas.draw(this, color, new Ellipse2D.Double(xPosition, yPosition, diameter, diameter)); canvas.wait(10); } }

// Erase the circle on screen. private void erase( ) { if (isVisible) { Canvas canvas = Canvas.getCanvas( ); canvas.erase(this); } }}

CS1101: Programming Methodology comp.nus.sg/~cs1101x

Documents

Transcript of CS1101: Programming Methodology comp.nus.sg/~cs1101x