Java Pattern Programs have always been one of the critical parts of the Java Interview questions. They look almost impossible to crack at a point, but these questions are practically based on mathematical logic and matrices' fundamentals. Hence Java Pattern Programs are greatly sought-after.
This Java Pattern Programs article covers almost every possible type of pattern programs that will give you a better understanding of the logic to decode the pattern and become capable of building one in your interview.
We will deal with 25 different types of Java Pattern Programs through the following docket.
Pattern 1
/*Star Pattern 1
*
* *
* * *
* * * *
* * * * * */
package Patterns;
public class Star {
public static void main(String[] args) {
int rows = 5;
for (int i = 1; i <= rows; ++i) { //Outer loop for rows
for (int j = 1; j <= i; ++j) { //Inner loop for Col
System.out.print("* "); //Print *
}
System.out.println(); //New line
}
}
}
Pattern 2
/*Star Pattern 2
* * * * *
* * * *
* * *
* *
* */
package Patterns;
public class Star {
public static void main(String[] args) {
int rows = 5;
for(int i = rows; i >= 1; --i) { //For Loop for Row
for(int j = 1; j <= i; ++j) { //For Loop for Col
System.out.print("* "); //Prints *
}
System.out.println(); //Get to newline
}
}
}
Pattern 3
/*Star Pattern 3
*
* *
* * *
* * * *
* * * * *
* * * *
* * *
* *
* */
package Patterns;
import java.util.Scanner;
public class Star {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in); //Input
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt();
for (int i = 0; i <= rows - 1; i++) { //For Loop for Row
for (int j = 0; j <= i; j++) { //For Loop for Col
System.out.print("*" + " "); //prints * and blank space
}
System.out.println(""); // new line
}
for (int i = rows - 1; i >= 0; i--) { //For Loop for Row
for (int j = 0; j <= i - 1; j++) { //For Loop for Col
System.out.print("*" + " "); //prints * and blank space
}
System.out.println("");// new line
}
sc.close();
}
}
Pattern 4
/*Star Pattern 4
*
* *
* * *
* * * *
* * * * * */
package Patterns;
public class Star {
public static void printStars(int n) {
int i, j;
for (i = 0; i < n; i++) {
for (j = 2 * (n - i); j >= 0; j--) { //For Loop for Row
System.out.print(" "); // Print Spaces
}
for (j = 0; j <= i; j++) { //For Loop for col
System.out.print("* "); // Print Star
}
System.out.println();
}
}
public static void main(String args[]) {
int n = 5; //Number of Rows
printStars(n);
}
}
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Pattern 5
/*Star Pattern 5
* * * * *
* * * *
* * *
* *
* */
package Patterns;
import java.util.Scanner;
public class Star {
public static void main(String[] args) {
Scanner S = new Scanner(System.in); //Input
System.out.println("Enter row value ");
int r = S.nextInt();
for (int i = r; i >= 1; i--) {
for (int j = r; j > i; j--) {
System.out.print(" "); // Prints Blank space
}
for (int k = 1; k <= i; k++) {
System.out.print("*"); //Prints *
}
System.out.println(" "); //Prints blank spaces
}
S.close();
}
}
Pattern 6
/*Star Pattern 6
*
**
***
****
*****
****
***
**
* */
package Patterns;
import java.util.Scanner;
public class Star {
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++) { //Rows Loop
System.out.print(" "); // Blank Space
}
for (int k = 1; k <= i; k++) { //Cols Loop
System.out.print("*"); // Prints *
}
System.out.println("");
}
for (int i = rows; i >= 1; i--) {
for (int j = i; j <= rows; j++) { //Rows Loop
System.out.print(" "); // Prints blank spaces
}
for (int k = 1; k < i; k++) { //Col Loop
System.out.print("*"); // Prints *
}
System.out.println(""); // New Line1
}
sc.close();
}
}
Pattern 7
/*Star Pattern 7
*
* *
* * *
* * * *
* * * * * */
package Patterns;
public class Star {
public static void printTriagle(int n) {
for (int i = 0; i < n; i++) {
for (int j = n - i; j > 1; j--) { //Loop for blank space
System.out.print(" "); //Print Space
}
for (int j = 0; j <= i; j++) { loop for star
System.out.print("* "); //Print Star
}
System.out.println(); //Newline
}
}
public static void main(String args[]) {
int n = 5;
printTriagle(n);
}
}
Pattern 8
/*Star Pattern 8
* * * * *
* * * *
* * *
* *
* */
package Patterns;
import java.util.Scanner;
public class Star {
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 loop for Rows
for (int j = 0; j <= i; j++) { //For loop for Col
System.out.print(" "); // blank space
}
for (int k = 0; k <= rows - 1 - i; k++) {
System.out.print("*" + " "); // prints * and blank space
}
System.out.println(); //Next line
}
sc.close();
}
}
Pattern 9
/*Star Pattern 9
*
***
*****
*******
*********
*******
*****
***
* */
package Patterns;
import java.util.Scanner;
public class Star {
public static void main(String args[]) {
int n, x, j, blank = 1;
System.out.print("Enter the value for rows: ");
Scanner s = new Scanner(System.in);
n = s.nextInt(); //input
blank = n - 1; // logic for balck spaces
//Upper star Pyramid
for (j = 1; j <= n; j++) {
for (x = 1; x <= blank; x++) {
System.out.print(" "); //print blank space
}
blank--;
for (x = 1; x <= 2 * j - 1; x++) {
System.out.print("*"); //Print Star
}
System.out.println("");
}
//Lower star Pyramid
blank = 1;
for (j = 1; j <= n - 1; j++) {
for (x = 1; x <= blank; x++) {
System.out.print(" "); //Print Spaces
}
blank++;
for (x = 1; x <= 2 * (n - j) - 1; x++) {
System.out.print("*"); //Print Star
}
System.out.println(""); //Print new line
}
}
}
Pattern 10
/*Star Pattern 10
* * * * *
* * * *
* * *
* *
*
*
* *
* * *
* * * *
* * * * * */
package Patterns;
import java.util.Scanner;
public class Star {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt(); //Input
//Upper Inverted Pyramid
for (int i = 0; i <= rows - 1; i++) {
for (int j = 0; j < i; j++) {
System.out.print(" "); Print blank space
}
for (int k = i; k <= rows - 1; k++) {
System.out.print("*" + " "); //Print star and blank space
}
System.out.println(""); //New line
}
//For lower Pyramid
for (int i = rows - 1; i >= 0; i--) {
for (int j = 0; j < i; j++) {
System.out.print(" "); //Print spaces
}
for (int k = i; k <= rows - 1; k++) {
System.out.print("*" + " "); //Print Star and Space
}
System.out.println(""); //Print New line
}
sc.close();
}
}
Pattern 11
/*Diagonal 11
*
*
*
*
* */
package Patterns;
public class Star {
public static void main(String[] args) {
int i, j;
for (i = 1; i <= 5; i++) {
for (j = 0; j < 5 - i; j++) {
System.out.print(" "); //Print blank space
}
System.out.print("*"); //Print Star and newline
}
}
}
Pattern 12
/*X Pattern 12
* *
* *
* *
*
* *
* *
* * */
package Patterns;
import java.util.*;
public class Star {
public static void main(String args[]) {
int i, j, n;
Scanner sc = new Scanner(System.in);
System.out.println("Enter a value for n");
n = sc.nextInt(); //Input
//Upper V pattern
for (i = n; i >= 1; i--) {
for (j = i; j < n; j++) {
System.out.print(" ");//print spaces
}
for (j = 1; j <= (2 * i - 1); j++) {
if (j == 1 || j == (2 * i - 1))//Logic for printing star
System.out.print("*");
else
System.out.print(" ");//if logic fails print space
}
System.out.println("");
}
//Lower Inverted V pattern
for (i = 2; i <= n; i++) {
for (j = i; j < n; j++) {
System.out.print(" ");//Print spaces
}
for (j = 1; j <= (2 * i - 1); j++) {
if (j == 1 || j == (2 * i - 1))//Logic for printing star
System.out.print("*");
else
System.out.print(" ");//if logic fails print space
}
System.out.println("");
}
}
}
Pattern 13
/*Inverted V 13
*
* *
* *
* *
* * */
package Patterns;
import java.util.Scanner;
public class Star {
public static void main(String[] args) {
Scanner cs = new Scanner(System.in); //Input
System.out.println("Enter the row size:");
int out, in;
int row_size = cs.nextInt();
int print_control_x = row_size;
int print_control_y = row_size;
for (out = 1; out <= row_size; out++) {
for (in = 1; in <= row_size * 2; in++) {
if (in == print_control_x || in == print_control_y) {
System.out.print("*");
} else {
System.out.print(" ");
}
}
print_control_x--;
print_control_y++;
System.out.println();
}
cs.close();
}
}
Pattern 14
/* V-pattern
* *
* *
* *
* *
* */
package Patterns;
public class Star {
static void pattern(int n) {
int i, j;
for (i = n - 1; i >= 0; i--) {
for (j = n - 1; j > i; j--) {
System.out.print(" "); //Print Space
}
System.out.print("*"); //Print star
for (j = 1; j < (i * 2); j++)
System.out.print(" ");//Print space
if (i >= 1)
System.out.print("*");
System.out.print("");//Enter newline
}
}
public static void main(String args[]) {
int n = 5;
pattern(n); //Pattern method call
}
}
Pattern 15
/*Rombus 15
*
* *
* *
* *
* *
* *
* *
* *
* */
package Patterns;
import java.util.Scanner;
public class Star {
public static void main(String[] args) {
System.out.println("Number of rows: ");
int rows = extracted().nextInt();
int i;
//upper inverted V pattern
for (i = 1; i <= rows; i++) {
for (int j = rows; j > i; j--) {
System.out.print(" "); //Print spaces
}
System.out.print("*"); //Print Spaces
for (int k = 1; k < 2 * (i - 1); k++) { /Logic for pattern
System.out.print(" "); //Print Spaces
}
if (i == 1) {
System.out.println(""); //Condition true, go to newline
} else {
System.out.println("*"); //else print star
}
}
//Lower v pattern
for (i = rows - 1; i >= 1; i--) {
for (int j = rows; j > i; j--) {
System.out.print(" "); //Print Spaces
}
System.out.print("*");
for (int k = 1; k < 2 * (i - 1); k++) { Logic for pattern
System.out.print(" ");
}
if (i == 1)
System.out.println(""); //newline
else
System.out.println("*"); //Print star
}
}
private static Scanner extracted() {
return new Scanner(System.in);
}
}
Pattern 16
/*Star Pattern 16
*
* *
* *
* *
********* */
package Patterns;
import java.util.Scanner;
public class Star {
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)) {
//Logic for printing Pattern
System.out.print("*"); //Print Star
} else {
System.out.print(" "); //Print Spaces
}
}
System.out.println("");
}
sc.close();
}
}
Pattern 17
/*Star Pattern 17
*********
* *
* *
* *
* */
package Patterns;
import java.util.Scanner;
public class Star {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows: ");
int rows = sc.nextInt(); //Row input
for (int i = rows; i >= 1; i--) {
for (int j = i; j < rows; j++) {
System.out.print(" "); //Print Spaces
}
for (int k = 1; k <= (2 * i - 1); k++) {
if (k == 1 || i == rows || k == (2 * i - 1)) { //logic to print Pattern
System.out.print("*"); //Ture prints star
} else {
System.out.print(" "); //False prints spaces
}
}
System.out.println("");
}
sc.close();
}
}
Pattern 18
/*Box 18
**********
* *
* *
* *
* *
* *
* *
* *
* *
********** */
package Patterns;
public class Star {
static void print_rectangle(int n, int m) {
int i, j;
for (i = 1; i <= n; i++) {
for (j = 1; j <= m; j++) {
if (i == 1 || i == n || j == 1 || j == m) //Logic to print
System.out.print("*"); //Tue?, print star
else
System.out.print(" "); //Tue?, print space
}
System.out.println();
}
}
public static void main(String args[]) {
int rows = 10, columns = 10;
print_rectangle(rows, columns); //Method call
}
}
Pattern 19
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5 */
package Patterns;
import java.util.Scanner;
public class Star {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in); //Input
System.out.println("Number of rows: ");
int rows = sc.nextInt();
for (int i = 1; i <= rows; i++) {
for (int j = 1; j <= i; j++) {
System.out.print(j + " "); //Print j value and space
}
System.out.println();
}
sc.close();
}
}
Pattern 20
/*Number Pattern 20 (Floyd's Triangle)
1
2 3
4 5 6
7 8 9 10
11 12 13 14 15 */
package Patterns;
public class Star {
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++ + " "); /Floyd’s triangle logic(prints K value and increments on every iteration)
}
System.out.println();
}
}
}
Pattern 21
/*Number Pattern 21 (Pascal's Triangle)
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1 */
package Patterns;
public class Star {
public static void main(String[] args) {
int x = 6;
for (int i = 0; i < x; i++) {
int num = 1;
System.out.printf("%" + (x - i) * 2 + "s", ""); //Pascals triangle logic
for (int j = 0; j <= i; j++) {
System.out.printf("%4d", num);
num = num * (i - j) / (j + 1);
}
System.out.println();
}
}
}
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/*Number Pattern 22
10101
01010
10101
01010
10101 */
package Patterns;
import java.util.Scanner;
public class Star {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Number of rows: ");
int rows = sc.nextInt(); //Input
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();
}
}
Pattern 23
/*Ruby Pattern 23
A
B B
C C
D D
C C
B B
A */
package Patterns;
import java.util.Scanner;
public class Ruby {
public static void main(String[] args) {
char[] alpha = { '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 digit = 0;
String[] ruby = new String[26];
System.out.print("Input Uppercase alphabet between A to Z:");
Scanner reader = new Scanner(System.in);
try {
char aplhabet = reader.next("[A-Z]").charAt(0);
for (int i = 0; i < alpha.length; i++) {
if (alpha[i] == aplhabet) {
digit = i;
break;
}
}
for (int i = 0; i <= digit; i++) {
ruby[i] = "";
for (int p = 0; p < digit - i; p++) {
ruby[i] += " ";
}
ruby[i] += alpha[i];
if (alpha[i] != 'A') {
for (int p = 0; p < 2 * i - 1; p++) {
ruby[i] += " ";
}
ruby[i] += alpha[i];
}
System.out.println(ruby[i]);
}
for (int i = digit - 1; i >= 0; i--) {
System.out.println(ruby[i]);
}
} catch (Exception e) { //Exception
e.printStackTrace();
} finally {
reader.close();
}
}
}
Pattern 24
/*Alphabet Pattern 24
A
A B
A B C
A B C D
A B C D E
A B C D E F */
package Patterns;
public class Alphabet {
public static void main(String[] args) {
int alphabet = 65; //ASCII value of “A”
for (int i = 0; i <= 5; i++) {
for (int j = 0; j <= i; j++) {
System.out.print((char) (alphabet + j) + " "); //Logic to print Alphabet pattern
}
System.out.println();
}
}
}
Pattern 25
/*Alphabet Pattern 25
A
A B
A B C
A B C D
A B C D E */
package Patterns;
public class Alphabet {
public static void main(String[] args) {
for (int i = 0; i <= 4; i++) {
int alphabet = 65; //ASCII value of “A”
for (int j = 4; j > i; j--) {
System.out.print(" "); //Print Space
}
for (int k = 0; k <= i; k++) {
System.out.print((char) (alphabet + k) + " "); //Print Alphabet
}
System.out.println();
}
}
}
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Conclusion
Java Pattern Programs are useful in enhancing the analytical capabilities of a Java Developer. Practicing them will not only help you to crack the interviews but also to decode the critical, logical issues in your code.
Followed by Java Pattern Programs, you can also go through some most frequently asked Java Interview Questions tutorial so that you can be interview ready at all times.
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If you have any queries regarding this "Java Pattern Programs" article, please leave them in the comments section, and our expert team will solve them for you at the earliest!
Himanshu Sukhija started his career 6 years ago with TCS in a QA role. But he was always interested in software development. When he reached out to his HR team for a role change, they suggested pursuing a professional course. He found Java courses offered by Simplilearn and finalized the Java Certification Training Course. After completing the course, he got a 100% hike and desired role! Checkout Simplilearn java full stack review here!
