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Java Interviews can give a hard time to programmers, such is the severity of the process. The ones who have attended the process will know that a pattern program is ought to pop up in the list of programs.
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This article precisely focuses on pattern programs in Java. I have classified the programs under the following clusters :
Pattern Programs in Java
Star Patterns in Java
First, let us begin with the basic and the commonly asked pattern program in Java i.e Pyramid.
1. Pyramid Program
* * * * * * * * * * * * * * *
Let’s write the java code to understand this pattern better.
public class Edureka
{
public static void pyramidPattern(int n)
{
for (int i=0; i<n; i++) //outer loop for number of rows(n) { for (int j=n-i; j>1; j--) //inner loop for spaces
{
System.out.print(" "); //print space
}
for (int j=0; j<=i; j++ ) //inner loop for number of columns
{
System.out.print("* "); //print star
}
System.out.println(); //ending line after each row
}
}
public static void main(String args[]) //driver function
{
int n = 5;
pyramidPattern(n);
}
}
2. Right Triangle Star Pattern
*
* *
* * *
* * * *
* * * * *
public class Edureka
{
public static void rightTriangle(int n)
{
int i, j;
for(i=0; i<n; i++) //outer loop for number of rows(n) { for(j=2*(n-i); j>=0; j--) // inner loop for spaces
{
System.out.print(" "); // printing space
}
for(j=0; j<=i; j++) // inner loop for columns
{
System.out.print("* "); // print star
}
System.out.println(); // ending line after each row
}
}
public static void main(String args[])
{
int n = 5;
rightTriangle(n);
}
}3. Left Triangle Star Pattern
*
* *
* * *
* * * *
* * * * *
public class Edureka
{
public static void printStars(int n)
{
int i, j;
for(i=0; i<n; i++) //outer loop for number of rows(n) { for(j=2*(n-i); j>=0; j--) // inner loop for spaces
{
System.out.print(" "); // printing space
}
for(j=0; j<=i; j++) // inner loop for columns
{
System.out.print("* "); // print star
}
System.out.println(); // ending line after each row
}
}
public static void main(String args[])
{
int n = 5;
printStars(n);
}
}
4. Diamond Shape Pattern Program in Java
Enter the number of rows: 5
*
***
*****
*******
*********
*******
*****
***
*
import java.util.Scanner;
public class Edureka
{
public static void main(String args[])
{
int n, i, j, space = 1;
System.out.print("Enter the number of rows: ");
Scanner s = new Scanner(System.in);
n = s.nextInt();
space = n - 1;
for (j = 1; j<= n; j++)
{
for (i = 1; i<= space; i++)
{
System.out.print(" ");
}
space--;
for (i = 1; i <= 2 * j - 1; i++)
{
System.out.print("*");
}
System.out.println("");
}
space = 1;
for (j = 1; j<= n - 1; j++)
{
for (i = 1; i<= space; i++)
{
System.out.print(" ");
}
space++;
for (i = 1; i<= 2 * (n - j) - 1; i++)
{
System.out.print("*");
}
System.out.println("");
}
}
}5. Downward Triangle Star Pattern
Enter the number of rows: 5
* * * * * * * * * * * * * * *
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: "); //takes input from user
int rows = sc.nextInt();
for (int i= rows-1; i>=0 ; i--)
{
for (int j=0; j<=i; j++)
{
System.out.print("*" + " ");
}
System.out.println();
}
sc.close();
}
} 6. Mirrored Right Triangle Star Program
Enter the number of rows: 5
*
**
***
****
*****
******
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter number of rows: "); // takes input from user
int rows = sc.nextInt();
for (int i= 0; i<= rows; i++)
{
for (int j=1; j<=rows-i; j++)
{
System.out.print(" ");
}
for (int k=0;k<=i;k++)
{
System.out.print("*");
}
System.out.println("");
}
sc.close();
}
}
7. Reversed Pyramid Star Pattern
Enter the number of rows: 5
* * * * *
* * * *
* * *
* *
*
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i= 0; i<= rows-1 ; i++)
{
for (int j=0; j<=i; j++)
{
System.out.print(" ");
}
for (int k=0; k<=rows-1-i; k++)
{
System.out.print("*" + " ");
}
System.out.println();
}
sc.close();
}
}
8. Right down Mirror Star Pattern
Enter the number of rows: 5
*****
****
***
**
*
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in); // takes input
System.out.println("Enter number of rows: ");
int rows = sc.nextInt();
for (int i= rows; i>= 1; i--)
{
for (int j=rows; j>i;j--)
{
System.out.print(" ");
}
for (int k=1;k<=i;k++)
{
System.out.print("*");
}
System.out.println("");
}
sc.close();
}
}
9. Right Pascal’s Triangle
Enter the number of rows: 5
* * * * * * * * * * * * * * * * * * * * * * * * *
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i= 0; i<= rows-1 ; i++)
{
for (int j=0; j<=i; j++) { System.out.print("*"+ " "); } System.out.println(""); } for (int i=rows-1; i>=0; i--)
{
for(int j=0; j <= i-1;j++)
{
System.out.print("*"+ " ");
}
System.out.println("");
}
sc.close();
}
}
10. Left Triangle Pascal’s
Enter the number of rows: 5
*
**
***
****
*****
****
***
**
*
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i= 1; i<= rows ; i++)
{
for (int j=i; j <rows ;j++)
{
System.out.print(" ");
}
for (int k=1; k<=i;k++) { System.out.print("*"); } System.out.println(""); } for (int i=rows; i>=1; i--)
{
for(int j=i; j<=rows;j++)
{
System.out.print(" ");
}
for(int k=1; k<i ;k++)
{
System.out.print("*");
}
System.out.println("");
}
sc.close();
}
}
11. Sandglass Star Pattern
Enter the number of rows: 5
* * * * *
* * * *
* * *
* *
*
*
* *
* * *
* * * *
* * * * *
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i= 0; i<= rows-1 ; i++)
{
for (int j=0; j <i; j++)
{
System.out.print(" ");
}
for (int k=i; k<=rows-1; k++) { System.out.print("*" + " "); } System.out.println(""); } for (int i= rows-1; i>= 0; i--)
{
for (int j=0; j< i ;j++)
{
System.out.print(" ");
}
for (int k=i; k<=rows-1; k++)
{
System.out.print("*" + " ");
}
System.out.println("");
}
sc.close();
}
}
12. Alphabet A Pattern
** * * *** * * * * * *
import java.util.Scanner;
public class Edureka
{
// Java program to print alphabet A pattern
void display(int n)
{
// Outer for loop for number of lines
for (int i = 0; i<=n; i++) {
// Inner for loop for logic execution
for (int j = 0; j<= n / 2; j++) {
// prints two column lines
if ((j == 0 || j == n / 2) && i != 0 ||
// print first line of alphabet
i == 0 && j != n / 2 ||
// prints middle line
i == n / 2)
System.out.print("*");
else
System.out.print(" ");
}
System.out.println();
}
}
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
Edureka a = new Edureka();
a.display(7);
}
}13. Triangle Star pattern
Enter the number of rows: 5
* * * * * * * *********
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i=1; i<= rows ; i++)
{
for (int j = i; j < rows ; j++) {
System.out.print(" ");
}
for (int k = 1; k <= (2*i -1) ;k++) {
if( k==1 || i == rows || k==(2*i-1)) {
System.out.print("*");
}
else {
System.out.print(" ");
}
}
System.out.println("");
}
sc.close();
}
}
14. Down triangle
Enter the number of rows: 5
*********
* *
* *
* *
*
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i=rows; i>= 1 ; i--)
{
for (int j = i; j < rows ; j++) {
System.out.print(" ");
}
for (int k = 1; k <= (2*i -1) ;k++) {
if( k==1 || i == rows || k==(2*i-1)) {
System.out.print("*");
}
else {
System.out.print(" ");
}
}
System.out.println("");
}
sc.close();
}
}
15. Diamond Star Pattern
Enter the number of rows: 5
*
* *
* *
* *
* *
* *
* *
* *
*
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i=1; i<= rows ; i++) { for (int j = rows; j > i ; j--) {
System.out.print(" ");
}
System.out.print("*");
for (int k = 1; k < 2*(i -1) ;k++) { System.out.print(" "); } if( i==1) { System.out.println(""); } else { System.out.println("*"); } } for (int i=rows-1; i>= 1 ; i--)
{
for (int j = rows; j > i ; j--) {
System.out.print(" ");
}
System.out.print("*");
for (int k = 1; k < 2*(i -1) ;k++) {
System.out.print(" ");
}
if( i==1)
System.out.println("");
else
System.out.println("*");
}
sc.close();
}
}
Now that we have implemented star pattern programs in Java. Let us move further and implement some Numeric patterns.
Numeric Pattern in Java
1. Simple number program
1 1 2 1 2 3 1 2 3 4 1 2 3 4 5
public class Edureka
{
public static void printNums(int n)
{
int i, j,num;
for(i=0; i<n; i++) // outer loop for rows
{
num=1;
for(j=0; j<=i; j++) // inner loop for rows
{
// printing num with a space
System.out.print(num+ " ");
//incrementing value of num
num++;
}
// ending line after each row
System.out.println();
}
}
public static void main(String args[])
{
int n = 5;
printNums(n);
}
}
2. Number Pattern Program in java
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args) {
int i, j, k = 1;
for (i = 1; i <= 5; i++) {
for (j = 1; j< i + 1; j++) {
System.out.print(k++ + " ");
}
System.out.println();
}
}
}
3. Pascal’s Triangle Program in Java
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args) {
int n = 5;
for (int i = 0; i < n; i++) {
int number = 1;
System.out.printf("%" + (n - i) * 2 + "s", "");
for (int j = 0; j <= i; j++) {
System.out.printf("%4d", number);
number = number * (i - j) / (j + 1);
}
System.out.println();
}
}
}
4. Diamond Pattern Program in Java
1 212 32123 4321234 32123 212 1
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args) {
for (int i = 1; i <= 4; i++)
{
int n = 4;
for (int j = 1; j<= n - i; j++) { System.out.print(" "); } for (int k = i; k >= 1; k--)
{
System.out.print(k);
}
for (int l = 2; l <= i; l++) { System.out.print(l); } System.out.println(); } for (int i = 3; i >= 1; i--)
{
int n = 3;
for (int j = 0; j<= n - i; j++) { System.out.print(" "); } for (int k = i; k >= 1; k--)
{
System.out.print(k);
}
for (int l = 2; l <= i; l++)
{
System.out.print(l);
}
System.out.println();
}
}
}
5. Number Pattern Programs in Java
Enter the number of rows: 5
1 2 2 3 3 3 4 4 4 4 5 5 5 5 5
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in); //Taking rows value from the user
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i = 1; i <= rows; i++)
{
for (int j = 1; j <= i; j++)
{
System.out.print(i+" ");
}
System.out.println();
}
sc.close();
}
}
6. Descending order Pattern
Enter the number of rows: 5
5 5 4 5 4 3 5 4 3 2 5 4 3 2 1
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
//Taking rows value from the user
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i = rows; i >= 1; i--)
{
for (int j = rows; j >= i; j--)
{
System.out.print(j+" ");
}
System.out.println();
}
sc.close();
}
}
7. Right Triangle Numeric Pattern
Enter the number of rows: 5
1 2 1 3 2 1 4 3 2 1 5 4 3 2 1
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i = 1; i <= rows; i++) { for (int j = i; j >= 1; j--)
{
System.out.print(j+" ");
}
System.out.println();
}
sc.close();
}
}
8. Binary Number Pattern
Enter the number of rows: 5
10101 01010 10101 01010 10101
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i = 1; i <= rows; i++)
{
int num;
if(i%2 == 0)
{
num = 0;
for (int j = 1; j <= rows; j++)
{
System.out.print(num);
num = (num == 0)? 1 : 0;
}
}
else
{
num = 1;
for (int j = 1; j <= rows; j++)
{
System.out.print(num);
num = (num == 0)? 1 : 0;
}
}
System.out.println();
}
sc.close();
}
}
9. Zeros/ ones Pattern Programs
Enter the number of rows: 5
1 10 101 1010 10101
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i = 1; i <= rows; i++)
{
for (int j = 1; j <= i; j++)
{
if(j%2 == 0)
{
System.out.print(0);
}
else
{
System.out.print(1);
}
}
System.out.println();
}
sc.close();
}
}
10. Diamond Numeric Pattern
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 5import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
int n = 5;
for (int i = 1; i <= n; i++)
{
for (int j = 1; j < i; j++)
{
System.out.print(" ");
}
for (int k = i; k <= n; k++) { System.out.print(k+" "); } System.out.println(); } for (int i = n-1; i >= 1; i--)
{
for (int j = 1; j < i; j++)
{
System.out.print(" ");
}
for (int k = i; k <= n; k++)
{
System.out.print(k+" ");
}
System.out.println();
}
}
}
Now that we have implemented numeric pattern programs in Java. Let us move further and implement some character/ alphabet patterns.
Alphabet/ Character Patterns in Java
1. Right Alphabetic triangle
A A B A B C A B C D A B C D E A B C D E F
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
int alphabet = 65;
for (int i = 0; i <= 5; i++)
{
for (int j = 0; j <= i; j++)
{
System.out.print((char) (alphabet + j) + " ");
}
System.out.println();
}
}
}
2. Alphabet/ Character Pattern Programs
A B B C C C D D D D E E E E E F F F F F F
import java.util.Scanner;
public class Edureka
{
public static void main(String[] args)
{
int alphabet = 65;
for (int i = 0; i<= 5; i++)
{
for (int j = 0; j <= i; j++)
{
System.out.print((char) alphabet + " ");
}
alphabet++;
System.out.println();
}
}
}
3. K Shape Character Pattern Program
A B C D E F A B C D E A B C D A B C A B A A A B A B C A B C D A B C D E A B C D E F
import java.util.Scanner;
public class Edureka
{public static void main(String[] args)
{
for (int i = 5; i >= 0; i--)
{
int alphabet = 65;
for (int j = 0; j <= i; j++)
{
System.out.print((char) (alphabet + j) + " ");
}
System.out.println();
}
for (int i = 0; i<= 5; i++)
{
int alphabet = 65;
for (int j = 0; j <= i; j++)
{
System.out.print((char) (alphabet + j) + " ");
}
System.out.println();
}
}
}
4. Triangle Character Pattern Program in Java
A
A B
A B C
A B C D
A B C D E
A B C D E F
public class Edureka
{
public static void main(String[] args)
{
for (int i = 0; i <= 5; i++) { int alphabet = 65; for (int j = 5; j > i; j--)
{
System.out.print(" ");
}
for (int k = 0; k <= i; k++)
{
System.out.print((char) (alphabet + k) + " ");
}
System.out.println();
}
}
}
5. Diamond Pattern in Java
Enter a Character between A to Z : F
A
B B
C C
D D
E E
F F
E E
D D
C C
B B
A
import java.util.Scanner;
public class Edureka
{public static void main(String[] args) {
char[] letter = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V',
'W', 'X', 'Y', 'Z' };
int letter_number = 0;
String[] diamond = new String[26]; // array of strings
System.out.print("Enter a Character between A to Z : ");
Scanner reader = new Scanner(System.in);
try {
char user_letter = reader.next("[A-Z]").charAt(0);
// search for letter number in the array letter
for (int i = 0; i < letter.length; i++) {
if (letter[i] == user_letter) {
letter_number = i;
break;
}
}
// construct diamond
for (int i = 0; i <= letter_number; i++) {
diamond[i] = "";
// add initial spaces
for (int j = 0; j < letter_number - i; j++) {
diamond[i] += " ";
}
// add letter
diamond[i] += letter[i];
// add space between letters
if (letter[i] != 'A') {
for (int j = 0; j < 2 * i - 1; j++) { diamond[i] += " "; } // add letter diamond[i] += letter[i]; } // Draw the first part of the diamond System.out.println(diamond[i]); } for (int i = letter_number - 1; i >= 0; i--)
{
// Draw the second part of the diamond
// Writing the diamondArray in reverse order
System.out.println(diamond[i]);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
reader.close();
}
}
}
So this brings us to the end of the top 30 pattern programs in java blog. I hope you found it informative and helped you in understanding Java Fundamentals.
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