Some Common Java Pattern Programs

package learn;

import java.util.Scanner;

public class Patterns {

    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        //Taking rows value from the user
        System.out.println("How many rows you want in this pattern?");
        int r = sc.nextInt();
        System.out.println("Here is your pattern....!!!");
       
     /*1
    1 2
    1 2 3
    1 2 3 4
    1 2 3 4 5*/
     
        for (int i = 1; i <= r; i++)
        {
            for (int j = 1; j <= i; j++)
            {
                System.out.print(j+" ");
            }
            System.out.println();
        }
            System.out.println("5---------------");
       
     /*1
        2 2
        3 3 3
        4 4 4 4
        5 5 5 5 5*/
       
        for(int i=1;i<=r;i++)
        {
        for(int j=1;j<=i;j++)
        {
        System.out.print(i+" ");
        }
        System.out.println();
        }
        System.out.println("---------------");
       
     /*1
        1 2
        1 2 3
        1 2 3 4
        1 2 3 4 5
        1 2 3 4 5 6
        1 2 3 4 5
        1 2 3 4
        1 2 3
        1 2
        1*/
       
        for(int i=1;i<=r;i++) {
        for(int j=1;j<=i;j++) {
        System.out.print(j+" ");
        }
        System.out.println();
        }
        for(int i=r-1;i>=0;i--) {
        for(int j=1;j<=i;j++) {
        System.out.print(j+" ");
        }
        System.out.println();
        }
        System.out.println("---------------");
       
     /*1 2 3 4 5
        1 2 3 4
        1 2 3
        1 2
        1 */
       
        for(int i=r;i>=1;i--) {
        for(int j=1;j<=i;j++) {
        System.out.print(j+" ");
        }
        System.out.println();
        }
        System.out.println("---------------");
       
     /*6 5 4 3 2 1
        5 4 3 2 1
        4 3 2 1
        3 2 1
        2 1
        1*/
       
        for (int i = r; i >= 1; i--)
        {
            for (int j = i; j >= 1; j--)
            {
                System.out.print(j+" ");
            }
           
            System.out.println();
        }
        System.out.println("---------------");
       
       /*1 2 3 4 5
  1 2 3 4
  1 2 3
  1 2
    1
  1 2
  1 2 3
  1 2 3 4
  1 2 3 4 5
     */
   
    //Printing upper half of the pattern
      for(int i=r;i>=1;i--) {
      for(int j=1;j<=i;j++) {
      System.out.print(j+" ");
      }
      System.out.println();
      }
    //Printing lower half of the pattern
      for(int i=2;i<=r;i++) {
      for(int j=1;j<=i;j++) {
      System.out.print(j+" ");
      }
      System.out.println();
      }
      System.out.println("---------------");
     
/      1
      2 2
    3 3 3
   4 4 4 4
         5 5 5 5 5 */
     
      int rc=1;
      for (int i = r; i > 0; i--)
        {
            //Printing i spaces at the beginning of each row
            for (int j = 1; j <= i; j++){
                System.out.print(" ");
            }
            //Printing 'rowCount' value 'rowCount' times at the end of each row
            for (int j = 1; j <= rc; j++){
                System.out.print(rc+" ");
            }
            System.out.println();
            //Incrementing the rowCount
            rc++;
        }
      System.out.println("---------------");
     
   /*1
      1 2 1
      1 2 3 2 1
      1 2 3 4 3 2 1
      1 2 3 4 5 4 3 2 1
      1 2 3 4 5 6 5 4 3 2 1
      1 2 3 4 5 6 7 6 5 4 3 2 1*/
   
      for (int i = 1; i <= r; i++)
        {
            //Printing first half of the row
            for (int j = 1; j <= i; j++)
            {
                System.out.print(j+" ");
            }
            //Printing second half of the row
            for (int k = i-1; k >= 1; k--)
            {
                System.out.print(k+" ");
            }
            System.out.println();
        }
      System.out.println("---------------");
   
     /*1
        2 1
        3 2 1
        4 3 2 1
        5 4 3 2 1
        6 5 4 3 2 1
        7 6 5 4 3 2 1*/
        for (int i = 1; i <= r; i++)
{
for (int j = i; j >= 1; j--)
{
System.out.print(j+" ");
}

System.out.println();
}
        System.out.println("---------------");

     /*1 2 3
        4 5
        6
        9 8 7 */
        int h=9;
        for(int i=1;i<=9;i++){
        if(i<=4||i>6) {
        if(i==4) {
        System.out.println(i);
        }
       
        else if(i>6){
        System.out.print(h-- +" ");
        }
        else {
        System.out.print(i+" ");
        }
        }
        else if(i == 5 || i == 6){
        System.out.println(i);
        }
        }
        System.out.println("\n---------------");
   
   /* 1
        2
        1 2 3 2 1
        4
        5 */
       
        for(int i=1;i<=5;i++) {
//         System.out.println(i);
        if(i==3) {
        for(int j=1;j<=3;j++) {
        System.out.print(j+" ");
        if(j==3) {
        for(int k=2;k>0;k--) {
        System.out.print(k+" ");
        }
        }
        }
        System.out.println();
        }
        System.out.println(i);
        }
        System.out.println("---------------");
   
        /* 1 * * * *
    1 2 * * *
    1 2 3 * *
    1 2 3 4 *
    1 2 3 4 5   */
   
     for(int i=1;i<=r;i++)  {
        for(int j=1;j<=r;j++) {
        if(j<=i) {
        System.out.print(j+" ");
        }
        else {
        System.out.print("*"+" ");
        }
        }
        System.out.println();
     }
    System.out.println("---------------");
   
 /*1
    2 1
    3 2 1
    4 3 2 1
    5 4 3 2 1*/
   
    for (int i = 1; i <= r; i++)
{
for (int j = i; j >= 1; j--)
{
System.out.print(j+" ");
}

System.out.println();
}
    System.out.println("---------------");
   
   /*12345
  2345
    345
        45
                  5
        45
    345
  2345
      12345*/
   
    for (int i = 1; i <= r; i++)
{
//Printing i spaces at the beginning of each row
for (int j = 1; j < i; j++) {
System.out.print(" ");
}
//Printing i to rows value at the end of each row
for (int j = i; j <= r; j++) {
System.out.print(j);
}
System.out.println();
}
//Printing lower half of the pattern
for (int i = r-1; i >= 1; i--)
{
//Printing i spaces at the beginning of each row
for (int j = 1; j < i; j++) {
System.out.print(" ");
}
//Printing i to rows value at the end of each row
for (int j = i; j <= r; j++) {
System.out.print(j);
}
System.out.println();
}
System.out.println("---------------");
  /* 1 2 3 4 5
       2 3 4 5
3 4 5
 4 5
  5
        4 5
      3 4 5
    2 3 4 5
  1 2 3 4 5 */   
   
for (int i = 1; i <= r; i++)
{
//Printing i spaces at the beginning of each row
for (int j = 1; j < i; j++) {
System.out.print(" ");
}
//Printing i to rows value at the end of each row
for (int j = i; j <= r; j++) {
System.out.print(j+" ");
}
System.out.println();
}
//Printing lower half of the pattern
for (int i = r-1; i >= 1; i--)
{
//Printing i spaces at the beginning of each row
for (int j = 1; j < i; j++) {
System.out.print(" ");
}
//Printing i to rows value at the end of each row
for (int j = i; j <= r; j++) {
System.out.print(j+" ");
}
System.out.println();
}
System.out.println("---------------");
   
     /*1
10
101
1010
10101*/

for (int i = 1; i <= r; i++)
{
for (int j = 1; j <= i; j++)
{
if(j%2 == 0)
{
System.out.print(0);
}
else
{
System.out.print(1);
}
}

System.out.println();
}
System.out.println("---------------");

             /*11111
11122
11333
14444
55555*/

for (int i = 1; i <= r; i++)
{
for (int j = 1; j <= r-i; j++)
{
System.out.print(1);
}

for (int j = 1; j <= i; j++)
{
System.out.print(i);
}

System.out.println();
}
System.out.println("---------------");
   
    /*10000
02000
00300
00040
00005*/

for (int i = 1; i <= r; i++)
{
for (int j = 1; j <= r; j++)
{
if(i == j)
{
System.out.print(i);
}
else
{
System.out.print(0);
}
}

System.out.println();
}
System.out.println("---------------");

    /*1
2 6
3 7 10
4 8 11 13
5 9 12 14 15*/

for (int i = 1; i <= r; i++)
{
int num = i;

for (int j = 1; j <= i; j++)
{
System.out.print(num+" ");

num = num+r-j;
}

System.out.println();
}
System.out.println("---------------");
   
        //Close the resources
        sc.close();
    }
}

10 Java Interview Programmatic Questions And Answers

1) FizzBuzz Problem.

Write a program in java which prints the numbers from 1 to 100. But, multiples of 3 should be replaced with “Fizz”, multiples of 5 should be replaced with “Buzz” and multiples of both 3 and 5 should be replaced with “FizzBuzz”?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

public class FizzBuzzProblem {     public static void main(String args[])     {         for(int i = 1; i <= 100; i++)         {             if((i % (3*5)) == 0)             {                 System.out.println("FizzBuzz");             }             else if ((i % 5) == 0)             {                 System.out.println("Buzz");               }             else if ((i % 3) == 0)             {                 System.out.println("Fizz");             }             else             {                 System.out.println(i);               }         }     } }

2) Write a Java program to find out the nearest number to 100 of the given two numbers?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

public class NearestNumber {     static int nearestTo100(int input1, int input2)     {         int diff1 = Math.abs(100 - input1);         int diff2 = Math.abs(100 - input2);         if(diff1 < diff2)         {             return input1;         }         else if (diff2 < diff1)         {             return input2;         }         else         {             return input1;         }     }     public static void main(String args[])     {         Scanner sc = new Scanner(System.in);         System.out.println("Enter First Number");         int input1 = sc.nextInt();         System.out.println("Enter Second Number");         int input2 = sc.nextInt();         System.out.println(nearestTo100(input1, input2));     } }

3) There are two numbers ‘a’ and ‘b’. Write a java program which should print ‘a’ if ‘a’ is bigger than ‘b’ by 2 or more or should print ‘b’ if ‘b’ is bigger than ‘a’ by 2 or more. Otherwise, it should print “INCONCLUSIVE”?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

public class BiggerNumber {     public static void main(String[] args)     {         Scanner sc = new Scanner(System.in);         System.out.println("Enter First number");         int a = sc.nextInt();         System.out.println("Enter Second Number");         int b = sc.nextInt();         if((a > b) && (a - b) >= 2)         {             System.out.println(a);         }         else if ((b > a) && (b - a) >=2)         {             System.out.println(b);         }         else         {             System.out.println("INCONCLUSIVE");         }     } }

4) Given a string “JAVAJ2EE”, write java program to print this string in the below format?

J
J A
J A V
J A V A
J A V A J
J A V A J 2
J A V A J 2 E
J A V A J 2 E E

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

public class PromrammingExample {     public static void main(String[] args)     {         String s = "JAVAJ2EE";         char[] c = s.toCharArray();         for(int i = 0; i < c.length; i++)         {             for(int j = 0; j <= i; j++)             {                 System.out.print(c[j]+" ");             }             System.out.println();         }     } }

5) How do you prove that String s1 = new String(“ONE”) and String s2 = “ONE” are two different objects in the memory?

Ans : Use “==” operator to compare s1 and s2. It will return ‘false’ if they are two different objects in the memory.

1 2 3 4 5 6 7 8 9 10 11

public class ProgrammingExamples {     public static void main(String[] args)     {         String s1 = "ONE";         String s2 = new String("ONE");         System.out.println(s1 == s2);      //Output : false     } }

6) What will be the output of this program?

1 2 3 4 5 6 7 8 9

public class CodingExamples {     public static void main(String args[])     {         int i = (byte) + (char) - (int) + (long) - 1;         System.out.println(i);     } }

Ans : 1

7) Will this program compiles successfully?

1 2 3 4 5 6 7 8 9 10 11

public class CodingExamples {     public static void main(String args[])     {         System.out.println(1);          http://javaconceptoftheday.com/         System.out.println(2);     } }

Ans : Yes. Compiler will treat ‘http’ as label and remaining part (of Line 7) will be commented.

8) What will be the output of the below program?

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public class CodingExamples {     public static void main(String[] args)     {         String[] s1 = {"ONE", "TWO", "THREE", "FOUR"};         String[] s2 = {"THREE", "TWO", new String("ONE")};         System.out.println(s1[0] == s2[2]);         System.out.println(s1[1] == s2[1]);         System.out.println(s1[2] == s2[0]);     } }

Ans :
false
true
true

9) Open a notepad in your system through a java program?

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public class ClassesAndObjects {     public static void main(String[] args)     {         try         {             Runtime.getRuntime().exec("notepad.exe");         }         catch (IOException e)         {             e.printStackTrace();         }     } }

10) Write a Java program to print the current date in “dd MMM yyyy” format?

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public class CurrentDate {     public static void main(String[] args)     {         Date date = new Date();         SimpleDateFormat formatter = new SimpleDateFormat("dd MMM yyyy");         System.out.println(formatter.format(date));     } }