Basic core java programs

// Data type example

public class MyProgram {

public static void main(String[] args) {
// TODO Auto-generated method stub

int  i = 111;
double y = 11.1234;
char ch1 = '!';
long z = 22222222L;

System.out.println(i);
System.out.println(y);
System.out.println(ch1);
System.out.println(z);
}
}

/*
Output:

111
11.1234
!
22222222

*/

// Generate a random number b/w 0, 1, 2, 3, 4, 5, 6 and print 0- Sunday, 1- Monday

public class Day {

public static void main(String[] args) {
// TODO Auto-generated method stub

int num = (int) (Math.random()*7);

if(num==0){
System.out.println("Sunday\n");
}

if(num==1){
System.out.println("Monday\n");
}

if(num==2){
System.out.println("Tuesday\n");
}

if(num==3){
System.out.println("Wednesday\n");
}

if(num==4){
System.out.println("Thursday\n");
}

if(num==5){
System.out.println("Friday\n");
}

if(num==6){
System.out.println("Saturday\n");
}
}
}


/*
Output: Wednesday

*/

// Find biggest of 2 numbers by using Unary operators?

public class BiggestNumber
{
public static void main(String [] args)
{
int num1=55;
int num2=43;
System.out.println((num1>num2)?(num1):(num2));
}
}

/*
Output: 55

*/

See full: Core Java Programs and Examples

// Free fall example of switch case?

public class SwitchDemo {

public static void main(String[] args) {
// TODO Auto-generated method stub

int i=10;

switch(i)
{
case 5: System.out.println("1");
break;

case 10: System.out.println("2");

case 11: System.out.println("3");

case 12: System.out.println("4");

case 13: System.out.println("5");

case 14: System.out.println("6");
break;

default: System.out.println("0");
break;
}
}
}

/*
Output:

2
3
4
5
6
*/

// Find a prime numbers?

public class Prime {

public static void main(String[] args) {


int num =13;
boolean  isPrime= true;
int i=2;

while(i<num-1)
{
if(num % 2==0)
{
isPrime =false;
break;
}
i++;
}
if(isPrime ==false)
{
System.out.print("Not a prime number");
}else{
System.out.print("Prime number");
}
}
}
/*
Output: Not a prime number

*/

// Second word reverse?

public class SecondWordReverse {

public static void main(String[] args) {
// TODO Auto-generated method stub

String s = "Info Tech Android Java";
int first=s.indexOf(' ');
int next=s.indexOf(' ', first+1);

System.out.println("Enter name is " +s);

System.out.print(s+ " second reverse word: ");

for(int i=next-1 ; i>first; i--)
{
System.out.print(s.charAt(i));
}
}
}

/*
Output:

Enter name is Info Tech Android Java
Info Tech Android Java second reverse word: hceT

*/

// Count words?

public class CountWords {

public static void main(String[] args) {
// TODO Auto-generated method stub

String s = "Info Technologies Bangalore India";
int count=1;

System.out.println("Enter name is " +s);

System.out.print(s+ " : ");

for(int i=0; i<=s.length()-1; i++)
{
char ch = s.charAt(i);
if(ch==' ')
{
count++;
}
}
System.out.print(count+ " words");
}
}


/*
Output:

Enter name is Info Technologies Bangalore India
Info Technologies Bangalore India : 4 words

*/

See full: Core Java Programs and Examples

// Print 8 16 10 20 12 24 14 ...10 elements using while loop?

public class SeriesDemo {

public static void main(String[] args) {
// TODO Auto-generated method stub

int i=8;
int j=16;
int count = 0;

while (count<=9)
{
System.out.print(" "+i);
System.out.print(" "+j);

i=i+2;
j=j+4;
count++;
}
}
}

/*
Output: 8 16 10 20 12 24 14 28 16 32 18 36 20 40 22 44 24 48 26 52

*/

// Fibonacci numbers?

public class FibonacciNumber {

public static void main(String[] args) {
// TODO Auto-generated method stub

int first=0;
int second=1;
// Fibonacci series
System.out.print("// Fibonacci series\n");
System.out.print(" " +first);
System.out.print(" " +second);

int sum = first + second;

while (sum<=100)
{
System.out.print(" " +sum);
first = second;
second = sum;
sum = first + second;
}
}
}

/*
Output:

// Fibonacci series
 0 1 1 2 3 5 8 13 21 34 55 89

*/

// Armstrong number

public class ArmstrongNumber {

public static void main(String[] args) {
// TODO Auto-generated method stub

// Armstrong number

int num= 153;
int temp = num;
int sum = 0;
System.out.println("// Armstrong number\n");
while (num>0)
{
int l = num%10;
sum = sum +(l*l*l);
num = num/10;
}
if (temp == sum)
{
System.out.println("Armstrong number: "+temp);
}
else
{
System.out.println("Not armstrong number: "+temp);
}
}
}

/*
Output:

// Armstrong number

Armstrong number: 153

*/

// Infinite loop examples

public class InfiniteDemo {

public static void main(String[] args) {
// TODO Auto-generated method stub

int i=1;

while(true){
System.out.println(" "+i);
i++;
}

}
}


/*
Output: 1 2 3...+ 2 billions ...-2 billions ..

*/

See full: Core Java Programs and Examples