Introduction
If you aspire to become a Java professional, then Pattern Programs in Java is one topic that you should prepare well. The pattern-based Java programs help analyze programming ability, and we have tried to provide pattern programs in Java with detailed explanations. This blog will be a comprehensive guide for how to do all pattern programs in Java.
A) Pyramid Pattern Programs in Java
The pyramid is one of the simple pattern programs in Java, that is often asked in interviews.
public class JigSawAcademy
{
public static void PyramidPattern(int n)
{
for (int i=0; i<n; i++) // number of rows(n)
{ for (int j=n-i; j>1; j–) // loop for spaces
{
System.out.print(” “); //print space
}
for (int j=0; j<=i; j++ ) //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);
}
}
Output:
*
* *
* * *
* * * *
* * * * *
It is one of the easiest pattern printing programs in java.
B) Star Pattern Programs in Java
Star pattern programs in java using a while loop creates many shaped patterns like pascal triangle, down triangle, and right-angle triangle pattern programs in Java. Some of the pattern programs in java using for loop are given here.
1. Right Triangle Star Pattern Programs in Java
public class RightTrianglePattern
{
public static void main(String args[])
{
// rows to print
int i, j, row=6;
//outer loop for rows
for(i=0; i<row; i++)
{
//inner loop for columns
for(j=0; j<=i; j++)
{
//prints stars
System.out.print(“* “);
}
// new line
System.out.println();
}
}
}
Output:
*
* *
* * *
* * * *
* * * * *
2. Left Triangle Star Pattern Programs in Java
public class JigSawAcademy
{
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);
}
}
Output:
*
* *
* * *
* * * *
* * * * *
3. Diamond Pattern Program in Java
import java.util.Scanner;
public class JigSawAcademy
{
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(“”);
}
}
}
Output:
*
***
*****
*******
*********
*******
*****
***
*
4. Downward Triangle Star Pattern Program in Java
import java.util.Scanner;
public class JigSawAcademy
{
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();
}
}
Output:
* * * * *
* * * *
* * *
* *
*
5. Mirrored Right Triangle Star Pattern Programs in Java
import java.util.Scanner;
public class JigSawAcademy
{
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();
}
}
Output:
*
**
***
****
*****
******
6. Reversed Pyramid Star Pattern Programs in Java
import java.util.Scanner;
public class JigSawAcademy
{
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();
}
}
Output:
* * * * *
* * * *
* * *
* *
*
7. Right down Mirror Star Pattern Programs in Java
import java.util.Scanner;
public class JigSawAcademy
{
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();
}
}
Output:
*****
****
***
**
*
8. Number Pattern Programs in Java
Pattern number programs in java print numbers in patterns like square, Damon, sandglass, and triangle.
import java.util.Scanner;
public class JigSawAcademy
{
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();
}
}
}
Output:
1
2 3
4 5 6
7 8 9 10
11 12 13 14 15
9. Square Number Pattern Programs in Java
import java.util.Scanner;
public class SquareNumber2 {
private static Scanner sc;
public static void main(String[] args)
{
int side, i = 0, j;
sc = new Scanner(System.in);
System.out.print(” Please Enter any Side of a Square : “);
side = sc.nextInt();
while(i < side)
{
j = 0;
while(j < side)
{
System.out.print(“1”);
j++;
}
i++;
System.out.print(“\n”);
}
}
}
Output:
1 2 3
1 2 3
1 2 3
Similarly, there are and that you can print in the same way.
10. Diamond Number Pattern Programs in Java
import java.util.Scanner;
public class JigSawAcademy
{
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();
}
}
}
Output:
1
212
32123
4321234
32123
212
1
11. Alphabet Pattern Programs in Java
import java.util.Scanner;
public class JigSawAcademy
{
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();
}
}
}
Output:
A
A B
A B C
A B C D
A B C D E
A B C D E F
12. Character Pattern Programs in Java
Character pattern programs in java using for loop prints the patterns in shapes of characters.
import java.util.Scanner;
public class JigSawAcademy
{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();
}
}
}
Output:
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
13. Square Pattern Programs in Java
import java.io.*;
class GFG {
// Function to print hollow rectangle
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)
System.out.print(“*”);
else
System.out.print(” “);
}
System.out.println();
}
}
// Driver program for above function
public static void main(String args[])
{
int rows = 6, columns = 20;
print_rectangle(rows, columns);
}
}
Output:
********************
* *
* *
* *
* *
********************
14. Pattern Matching Pattern Programs in Java
public class REmatch {
public static void main(String[] argv) {
String patt = “Q[^u]\\d+\\.”;
Pattern r = Pattern.compile(patt);
String line = “Order QT300. Now!”;
Matcher m = r.matcher(line);
if (m.find()) {
System.out.println(patt + ” matches \”” +
m.group(0) +
“\” in \”” + line + “\””);
} else {
System.out.println(“NO MATCH”);
}
}
}
Output:
Q[\^u]\d+\. matches “QT300.” in “Order QT300. Now!”
15. String Pattern Programs in Java
package com.javainterviewpoint;
import java.util.Scanner;
public class Pattern24
{
public static void main(String[] args)
{
// Create a new Scanner object
Scanner scanner = new Scanner(System.in);
// Get the String from the user
System.out.println(“Enter the String which needs to be printed “);
String input = scanner.nextLine();
System.out.println(“** Printing the pattern… **”);
for (int i = 1; i <= input.length(); i++)
{
for (int j = input.length(); j > i; j–)
{
System.out.print(” “);
}
for (int k = i * 2 – 1; k >= 1; k–)
{
System.out.print(input.charAt(i – 1));
}
System.out.println(“”);
}
}
}
Output:
Enter the string which needs to be printed
JAVA
** Printing the pattern… **
J
AAA
VVVVV
AAAAAAA
16. Word Pattern Programs in Java
public boolean wordPattern(String pattern, String str) {
String[] arr = str.split(” “);
//prevent out of boundary problem
if(arr.length != pattern.length())
return false;
HashMap<Character, String> map = new HashMap<Character, String>();
for(int i=0; i<pattern.length(); i++){
char c = pattern.charAt(i);
if(map.containsKey(c)){
String value = map.get(c);
if(!value.equals(arr[i])){
return false;
}
}else if (map.containsValue(arr[i])){
return false;
}
map.put(c, arr[i]);
}
return true;
}
17. Matrix Pattern programs in java
import java.io.*;
class GFG
{
// Function to
// print the pattern
static void printPattern(int n)
{
// number of rows and
// columns to be printed
int s = 2 * n – 1;
// Upper Half
for (int i = 0;
i < (s / 2) + 1; i++)
{
int m = n;
// Decreasing part
for (int j = 0; j < i; j++)
{
System.out.print(m + ” “);
m–;
}
// Constant Part
for (int k = 0;
k < s – 2 * i; k++)
{
System.out.print(n – i + ” “);
}
// Increasing part.
m = n – i + 1;
for (int l = 0; l < i; l++)
{
System.out.print(m + ” “);
m++;
}
System.out.println();
}
// Lower Half
for (int i = s / 2 – 1;
i >= 0; i–)
{
// Decreasing Part
int m = n;
for (int j = 0; j < i; j++)
{
System.out.print(m + ” “);
m–;
}
// Constant Part.
for (int k = 0;
k < s – 2 * i; k++)
{
System.out.print(n – i + ” “);
}
// Decreasing Part
m = n – i + 1;
for (int l = 0; l < i; l++)
{
System.out.print(m + ” “);
m++;
}
System.out.println();
}
}
// Driver Code
public static void main (String[] args)
{
int n = 3;
printPattern(n);
}
}
Output:
3 3 3 3 3
3 2 2 2 3
3 2 1 2 3
3 2 2 2 3
3 3 3 3 3
18. Odd Number Pattern Programs in Java
import java.util.Scanner;
class Pattern {
static void display(int n)
{
int i, j, k;
for (i = 1; i <= n; i++) {
for (j = 1, k = i; j <= i; j++, k–) {
if (k % 2 == 0) {
// displaying the numbers
System.out.print(j);
}
else {
// displaying the stars
System.out.print(“*”);
}
}
System.out.print(“\n”);
}
}
// Driver Code
public static void main(String[] args)
{
// Get n
int n = 5;
// Print the pattern
display(n);
}
}
Output:
*
1
*
2
*
1*3*
*
2*4
19. Pascal’s Triangle Pattern Programs in Java
import java.util.Scanner;
public class JigSawAcademy
{
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();
}
}
}
Output:
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
Conclusion
This blog is a collection of different pattern programs in java; From basic pattern programs in java to difficult pattern programs in java. If you wish to learn more about Java programming, check out our Master Certificate in Full Stack Development program!
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