Simple Java Programs

1. SAMPLE JAVA PROGRAMS

2. Comparing Two Numbers
This is a very simple example of Java
that teaches you the method of comparing
two numbers and finding out the greater
one.

3. •First of all, name a class "Comparing" and take two
variables in this class (ie, a & b). Here we have taken
a=5 and b=10,
•Now we have to find out whether a=b, a>b or b>a.
•To find out this apply if and else condition one by
one.
•Now apply the condition "if (a=b)", if this satisfies
then print both are equal.
•If this doesn't satisfy, then check whether a>b by
applying the "else if" condition and print the
message "a is greater than b”.
•Again this doesn't satisfy then 'else' condition as
shown in the example will show that b is greater
than a.

4. code of the program:
class Comparing{
public static void main(String[] args) {
int a=5, b=10;
if (a == b){
System.out.println("Both are equal");
}
else if(a>b){
System.out.println("a is greater than b");
}
else{
System.out.println("b is greater than a");
}
}
}

5. How to compile & run
Compiling:
javac Comparing.java
Run:
java Comparing
Out put:
b is greater than a

6. Program to list all even numbers
between two numbers
This is a program for listing out all the
even numbers between two numbers.

7. •For this first create a class named AllEvenNum under the
java.io package. Now use the try/catch exception to avoid any
kind of input error.
• After this create a buffer class in which all the input data are
stored and modified. Then give message as to "Enter number"
in the System method.
•As we have to find out all the even numbers between 1 and
the input number, define an integer variable 'num'.
•Now apply ParseInt method that parses the string character
into decimal integer.
•Apply for loop in which define an integer i=1 and i<= num
also with an increment operator. Then apply the if condition
that i/2=0 i.e. to find even numbers which are divided by the
integer 2. In the end apply the catch exception.

8. code of the program:
import java.io.*;
class AllEvenNum{
public static void main(String[] args) {
try{
BufferedReader br1 = new BufferedReader
(new InputStreamReader( System.in));
System.out.println("Enter number : ");
int num = Integer.parseInt(br1.readLine());
System.out.println("Even Numbers:");
for (int i=1;i <=num ; i++){
if(i%2==0 ){
System.out.print(i+",");
} }
}
catch(Exception e){
e.printStackTrace();
}
}
}

9. How to compile & run
Compiling:
javac AllEvenNum.java
Run:
java AllEvenNum
Note:
This program cannot be run in jdeveloper

10. calculate area and perimeter of a
circle
This is a program to calculate the area and
perimeter of a circle

11. •First of all name a class as "CircleArea" under java I/
O package and define and integer r=1o, which is the
radius of the circle. Now use try exception to handle
errors and other exceptional events.
•Now create the Math class in which all the
mathematical functions are defined. This Math class
can be imported from the java.lang.* package.
•Formula for calculate area
area = java.lang.Math.PI*r*r;
•Formula for calculate area
perimeter =2*java.lang.Math.PI*r ;
•Before ending the program use the Catch mechanism
that detects and catch user input errors.

12. code of the program:
import java.io.*;
class CircleArea{
public static void main(String[] args){
int r=10;
try
{
double area = java.lang.Math.PI*r*r;
System.out.println("Area of Circle : "+area);
double perimeter =2*java.lang.Math.PI*r ;
System.out.println("Perimeter of Circle : "+perimeter);
}
catch(Exception e){
System.out.println("Error : "+e);
}
}
}

13. How to compile & run
Compiling:
javac CircleArea.java
Run:
java CircleArea
Out put:
Area of Circle : 314.1592653589793
Perimeter of Circle : 62.83185307179586

14. Calculate Factorial Of A Given
Number
Here is a program to calculate factorial of a
given number.
•First of all define a class "Factorial" under the Java I/
O package.
•Define 'a' as an integer with value 10. Take an
integer variable as fact=1.
•Now applying for loop with conditions as integer
i=1(intializer), i<=a and i++ as increment operator.
So output result will be like fact=fact*i.
•Print the result.

15. code of the program:
import java.io.*;
class Factorial{
public static void main(String[] args) {
try{
int a= 10;
int fact= 1;
System.out.println("Factorial of " +a+ ":");
for (int i= 1; i<=a; i++){
fact=fact*i;
}
System.out.println(fact);
}
catch (Exception e){
e.printStackTrace();
}
}
}

16. How to compile & run
Compiling:
javac Factorial.java
Run:
java Factorial
Out put:
Factorial of 10:
3628800

17. calculating area and perimeter of
a rectangle
Here is a program for calculating the area and
perimeter of a rectangle.

18. •First of all create a class named RecArea
under Java.io package. Now define two
integer variable 'length' and 'width‘ with
values 10 and 50.
•Calculate area and Perimeter by applying the
formulas
area = length*width;
perimiter = 2*(length+width);
•Print result in the console

19. import java.io.*;
class RecArea{
public static void main(String[] args)
{
int length=10;
int width=50;
try{
int area = length*width;
System.out.println("Area of Rectangle : "+area);
int perimiter = 2*(length+width);
System.out.println("Perimeter: " + perimiter);
}
catch(Exception e){System.out.println("Error : "+e);}
}
}

20. How to compile & run
Compiling:
javac RecArea.java
Run:
java RecArea
Out put:
Area of Rectangle : 500
Perimeter: 120

21. program to construct a triangle
with the ‘*’
Here is the program for constructing a shape of
triangle by using '*'.

22. •Make a class named ‘Triangle‘.
•Define an integer 'a‘ with value 5.
•Now apply the for loop and define an integer 'i' and
it should be either less than or equal to the integer
"a“.
for (int i=1; i<a;i++ )
•Again define another integer type variable "j" in
another for loop.
for (int j=1; j<=i;j++ )
•Here in the second for loop "j" the number of times
we have to print *(You can take any other object
instead of *) .

23. import java.io.*;
Class Triangle{
public static void main(String[] args) {
try{
int a= 5;
for (int i=1; i<a;i++ ){
for (int j=1; j<=i;j++ ){
System.out.print("*");
}
System.out.println("");
}
}
catch(Exception e){}
}
}

24. How to compile & run
Compiling:
javac Triangle.java
Run:
java Triangle
Out put:
*
**
***
****

25. Listing out leap years between
certain period
Here is the program for finding and listing out
the leap years between two years. In the
following example we have to find out the leap
years between 1990 and 2010.

26. •First define the two years under a class "leapyears".
Let i = 2010 and n=1990.
•Now with the help of for loop method initialize the
year as n=1990 and n<=i. Also apply the increment
statement in the loop as we have to check one by
one.
•As we know a leap year is divisible by 4, define an
integer l=n%4.
•So if 'n' is divisible by 4 or l=0, then the particular
year can be a leap year.
•For checking this, apply the if statement and if this
satisfies then, the year will be a leap year.
•For listing out each year write "+n" in the
System.out.println.

27. import java.io.*;
Class Leapyears {
public static void main(String[] args) {
{
int i=2010;
int n;
for (n=1990; n<=i ; n++)
{
int l=n%4;
if (l==0){
System.out.println("leap year: "+n);
}
}
}
}
}

28. How to compile & run
Compiling:
javac Leapyears.java
Run:
java Leapyears
Out put:
leap year: 1992
leap year: 1996
leap year: 2000
leap year: 2004
leap year: 2008