Learning JAVA through BlueJ

BlueJJ : An Intr Blue Introd oduc ucti tion on towards JAVA Expertise Dheeraj Mehrotra City Montessori School Kanpur Kanpur Road, Road, Luckn Lucknow ow [email protected] www.computerscienceexpertise.com

computerscienceexpertise.com TOWARDS QUALITY LITERACY

Credits Michael Kölling School of Network Computing Monash Monash Unive Universit rsity y, Austra Australia lia


What is BlueJ? BlueJ BlueJ is a Java™ Java™ develop developmen mentt environ environment ment speci specifica fically lly designed for teaching at an introductory level. It was designed designed and implemented implemented by the BlueJ team at Monash Monash University, Melbourne, Australia. More informat information ion about about BlueJ is available available at http://bluej.monash.edu.. http://bluej.monash.edu


BlueJ Installation BlueJ is distributed distributed as as an archive archive of Java classes classes in “jar” format. format. Installin Installing g it is quite straightforward. Prerequisites You must have JDK 1.2.2 or later installed on your system to use BlueJ. Some functionality works better with JDK 1.3, so it is worth getting or updating up dating to the latest JDK release. If you do not have JDK installed you can download it from Sun’s web site at http://java.sun.com/j2se/ .


Getting BlueJ The BlueJ distributio distribution n file file is is named named bluej- xxx.jar , where xxx is a version number. For example, example, the BlueJ BlueJ version version 1.1.1 1.1.1 distribution distribution is is named bluej-111.jar . You might get this file on disk, or or you can dow download nload it from from the BlueJ web site at http://bluej.monash.edu http://bluej.monash.edu..


Installing BlueJ Windows: Double-click the install file (bluejsetup ). ). And follow the instructions further.


Installing BlueJ


Installing BlueJ


Blue lueJ ins insta tallla lati tion on


Blue lueJ Ins Instal alla lati tion on














Installing BlueJ

Once the BlueJ with JDK is installed, installed, double click the above icon to to have the following screen. computerscienceexpertise.com TOWARDS QUALITY LITERACY

Blue Bl ueJJ Open Openin ing g Sc Scre reen en


Opening a project in BlueJ

BlueJ projects, projects, like standard standard Java packages, packages, are directories directories containing containing the files included included in the project. project. If you start BlueJ BlueJ from a command line, line, and you give a project as an argument, it will automatically be opened. If you start start BlueJ BlueJ without without an argument, argument, use the the Project – Open... menu command to select and open a project.


Coding a program


Compiling the program


Close the program


Next Screen


Creating an Object


Creating an Object


Creating Object


Executing the program through objects

Right Click the Mouse


Executing an Object

Select Void computerscienceexpertise.com work(String) TOWARDS QUALITY LITERACY function

Executing the program Supply The String as Input Wit Within hin “ “


INPUT STRING


Output Screen


Example Program 1 // Program to compute and print all prime numbers between 100 and 500 class test1 { void prime() { int i,j,s i,j,s=0, =0,d=0 d=0;; for(i=100;i<500;i++) { s=0; for(j=1;j<=i;j++) { if(i%j==0) s=s+1; }

if(s==2) { System.out.println(i+" "); d=d+1; } } System.out.println(); System.out. System.out.print println("t ln("the he no. of prime no. are = "+d); } }


Example Program 2 // Create a program to define a function found() // to print the Highest Common Factor of any two numbers.

System.out. System.out.print println("T ln("The he HCF of the given two numbers is "+h); } }

class compute { public public void void ffoun ound(i d(int nt a, int int b) // // declaration of the function { int int p,h=0 p,h=0;; p=a*b; for (int i=1;i<=p;i++ i=1;i<=p;i++)) { if (a%i==0 && b%i==0) h=i; } computerscienceexpertise.com TOWARDS QUALITY LITERACY

Example Program 3 // Program to print the characters of the string present at odd positions. public class odd { privat private e int x,i,l x,i,l;; public odd() { x = 0; }

public void array1(String a) { l=a.length(); System.out.print("the characters of the string s tring "+a+" at odd positions are:"); for(i=0;i

Example Program 4 // Program to print the characters of the string present at even positions. public class even { privat private e int x,i,l x,i,l;; public even() { x = 0; }

public void array1(String a) { l=a.length(); System.out.print("the characters of the string "+a+" at even positions are:"); for(i=0;i

Example Program 5 //Write a program to compute prime factors of any entered number with the help of a function pfact(). class compute { void pfact(int pfact(int n) // Definiti Definition on { int int t=-1 t=-1;; int anum[]=new anum[]=new int[10]; int[10]; for (int i=1;i<=n-1;i i=1;i<=n-1;i++) ++) { if (n%i==0) { t=t+1; anum[t]=i; }

for (int count = 0, 0, k=0;k<=t; k=0;k<=t;k++) k++) { System.out.println(anum[k]+" is a factor of "+n); for (int m=1;m<=anum m=1;m<=anum[k];m [k];m++) ++) { if (anum[k]%m== (anum[k]%m==0) 0) count = count count + 1; } if (count==2) System.out.println(anum[k]+" is also prime"); count = 0; } } }


Example Program 6 // Program to print the sum of the odd digits of an entered number

System.out. System.out.print println("T ln("The he sum of the odd digits of the number is "+sum);

public class prog

}

{

} public public void void work(int work(int n) { int digit, digit, sum= sum=0; 0; while(n>0) { digit = n%10; // checking digit even if (digit%2!=0) sum = sum sum + digit digit;; n=n/10; } computerscienceexpertise.com TOWARDS QUALITY LITERACY

Example Program 7 // length of each word of a sentence // print longest word

class string4 { privat private e int i,l,c i,l,c;; char z;

public string4() { // initialise instance variables c=0; }

public void work(String work(String s) {s=s+" "; l=s.length(); for(i=0;i
Example Program 8 // Program to display the factorial of any entered number using the do-while loop. class dowhileloop { public void work(int work(int N) { in t i; double fact; fact=1; i = 1; whilile(i wh e(i <=N) <=N) { fact = fact*i; i++; } System.out.print("The factorial of the Number Number is" +fact); } computerscienceexpertise.com } TOWARDS QUALITY LITERACY

Example Program 9 // Program to print the digits of an entered number in descending order. public class prog { public public void void work(int work(int n) { int digit, digit,num num=n; =n; System.out.println("The entered number is "+n); System.out.println("The sorted digits in descending order is ");

for(int i=9;i>=0;ii=9;i>=0;i--) -) { while(n>0) { digit = n%10; if (digit==i ) System.out.print(digit); n=n/10; } n=num; } } }


Example Program 10 public void void sampleMethod(S sampleMethod(Strin tring g str) { // Program to input a string and l=str.length(); print each word in reverse. System.out.print(str); for(i=0;i=p;j--) /** { * Constructor for objects of char b=str.charAt(j); class reverse System.out.print(b); */ } public reverse() System.out.print(" "); { p=i; p=0; // initialise initialise instance instance } variables } computerscienceexpertise.com } TOWARDS QUALITY LITERACY } }

A Revision Tour o o o o

What is BlueJ? Java : It’s utility in totality? Execution of class files. Instat Instatia iati tion on of Object Objects. s. o

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Learning JAVA through BlueJ

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