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Robotint streetint avenueDirection directionThingBag backbag......Robot(City aCity, int aStreet, int aAvenue, Direction aDir)void move()void turnLeft()void pickThing()void putThing()......

Services, methods

Attributes

UML class diagram for Robot

Class name

Constructor

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Modeling what?

Modeling Robots in a City with Software Classes.

Robotint streetint avenueDirection directionThingBag backbag......

Robot(City aCity, int aStreet, int aAvenue, Direction aDir)void move()void turnLeft()void pickThing()void putThing()...

CityString nameint stree_Noint ave_No..........

City(...........)................

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Task: deliver X from (1,2) to (3,1) and step away

X01234

0 1 2 3 4import becker.robot.*;public class DeliverX{

public static void main(String args[]){ // set up Initial situation City A = new City();

Thing X = new Thing(A,1,2);Robot karel = new Robot(A,0,0,

Direction.East); // direct the robot

karel.move();karel.move();karel.turnLeft(); karel.turnLeft();

karel.turnLeft(); karel.move();karel.pickThing();

karek.move(); karel.move();karel.turnLeft(); karel.turnLeft();karel.turnLeft();karel.move(); karel.putThing();karel.move();

}}

named Karel

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Task: deliver X from (1,2) to (3,1) and step away

X01234

0 1 2 3 4

import becker.robot.*;public class DeliverX{ public static void main(String args[]){ // set up Initial situation City A = new City();

Thing X = new Thing(A,1,2);Robot karel = new Robot(A,0,0,

Direction.East); // direct the robot

karel.turnLeft(); karel.turnLeft(); karel.turnLeft(); karel.move();

karel.turnLeft();karel.move();karel.move();karel.pickThing();karel.turnLeft(); karel.turnLeft();

karel.turnLeft(); karek.move();

karel.turnLeft(); karel.turnLeft(); karel.turnLeft();

karel.move();karel.turnLeft();karel.move();

karel.putThing();karel.turnLeft(); karel.turnLeft();karel.turnLeft();karel.move();

}}

named Karel

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import becker.robot.*;

public class DeliverX{

public static void main(String args[]){ // set up Initial situation City A = new City();

Thing X = new Thing(A,1,2);Robot karel = new Robot(A,0,0,Direction.East);

// direct the robot karel.move();karel.move();karel.turnLeft(); karel.turnLeft();

karel.turnLeft(); karel.move();karel.pickThing();

karek.move(); karel.move();karel.turnLeft(); karel.turnLeft();karel.turnLeft();karel.move(); karel.putThing();karel.move();

}}

Anatomy of a Java Program

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Package: collection of classes// Java API: Java Application Programming Interface// (java., javax.)// GUI: Graphical User Interface //// using swing package, JOptionPane class// showMessageDialog method

import javax.swing.JOptionPane;

public class TestPane{

public static void main(String args[]){ JOptionPane.showMessageDialog(

null,"Welcome\nTo\nswing\nPackage");

System.exit(0); }}

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A Java Program:// Text-printing program.

public class Welcome1 {

// main method begins execution of Java application

public static void main( String args[] ) { System.out.println( "Welcome to Java Programming!" );

} // end method main

} // end class Welcome1

/**********************************************************(C) Copyright 1992-2003 by ...... * * ***********************************************************/

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Reusing Codes

1. Composition

2. Inheritance

A class has another class, “has a” relation

A class inherits another class, “is a” relation

A car has an engine

An SUV is a car

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Composition: has a

A DeliverX has a main, The main has a City, Thing, and a Robot

import becker.robot.*;public class DeliverX{

public static void main(String args[]){ // set up Initial situation City A = new City();

Thing X = new Thing(A,1,2);Robot karel = new Robot(A,0,0,

Direction.East); ...... }}

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Composition: has a

A BankAccount has a Client, has a List of BankTransaction

public class BankAccount { private Client client; private List<BankTransaction> transactions; // other fields ...}

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Classes:A class is a concept of something

Vehicle4 wheels, seats, engine, windows, color……

accelerate, start, stop, turn, lock, ...............

Truck…………

Sedan…………

SUV…………

Matrix…………

Focus…………

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Inheritance: From membership point of view

Vehicle

SUV Honda Pilot

Object

NumberIntegerDouble

Base concept

Derived concept

JavaBase class

Derived class

A SUV is a vehicle, but a vehicle may not be a SUV

Any SUV is a Vehicle

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Inheritance: From functionality point of view

SUV

Vehicle

Derived class

Base class

All vehicle can do, SUV can too

The SUV has every properties and function of the Vehicle

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UML (Unified Modeling Language) Diagram

Vehicle

Truck SedanSUV

MatrixFocusHonda Pilot

Matrix XRS

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A- my_a: int+get_a():int

B- my_b: int+get_b():int

B- my_b: int+get_a():int+get_b():int

=

my_a is invisible to B

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Base class (superclass) & Derived class (extended subclass)

// A is a base classpublic class A { private int my_a;

Public A(int a) { my_a = a; }

public int get_a() { return my_a; }}

// B is a derived classPublic class B extends A { private int b;

public B(int a, int b) { super(a); this.b = b; }

public int get_b() { return b; }}

A a = new A(2); B b = new B(3,7);

I = a.get_a(); J = b.get_a(); K = b.get_b();

B inherits A’s functions andvariables.

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An enhanced robot

Robotint streetint avenueDirection directionThingBag backback

Robot(City aCity, int aStreet, int anAvenue, Direction aDir)void move()void turnLeft()void pickThing()void putThing()

ExperimentRobot

ExperimentRobot(City aCity, int aStreet, int anAvenue, Direction aDir)void turnAround();void turnRight();void move3();

=

ExperimentRobot

int streetint avenueDirection directionThingBag backback

ExperimentRobot(City aCity, int aStreet, int anAvenue, Direction aDir)void move()void turnLeft()void pickThing()void putThing()void turnAround();void turnRight();void move3();

18

A Java program

import javax.swing.JOptionPane;public class time{ public static void main(String args[]){

int x,y,z; String X,Y;

X = JOptionPane.showInputDialog("Input x"); Y = JOptionPane.showInputDialog("Input y"); x = Integer.parseInt(X); y = Integer.parseInt(Y);

z = x*y;

JOptionPane.showMessageDialog( null, x + " * " + y + " = " + z, "The product of " + x + " and " + y, JOptionPane.PLAIN_MESSAGE ); System.exit(0); }}

classes methods

package

arguments

Variable declaration

class defined in the package

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Selection sort algorithm in Java

public static class SelectionSort {public void sort(int a[]) { for (int i = 0; i<a.length-1; i++) { // select one for a[i]

int j = min(a,i); exchange(a,i,j); } }

// select the minimum between a[s] to the end private int min(int a[], int s) {int m = s; for (int i=s; i<a.length;i++)

if (a[i] < a[m]) m=i; return m; }

private void exchange(int[] a, int i, int j) { int temp = a[i];

a[i] = a[j]; a[j] = temp;

}

} // end of SelectionSort