Java Code Example: Christmas Tree Pattern

This code is an example of how to create a Christmas tree pattern using asterisks (*) and vertical bars (|).

Code Example

public class PatternChristmasTree {
	public static void main(String[] args) {
		int n = 10, i, j, k;

		for (i = 0; i < n; i++) {
			for (j = 1; j <= n - i; j++) {
				System.out.print(" ");
			}
			System.out.print("*");
			for (k = 0; k <= i-1; k++) {
				System.out.print("|");
			}
			for (j = 1; j < i; j++) {
				System.out.print("|");
			}
			
			if (i > 0) {
				System.out.print("*");
			}
			System.out.println();
		}
	}
}

Output

The result of running this program is a pattern that looks like a Christmas tree made up of stars and vertical bars.

         *|*
        *|||*
       *|||||*
      *|||||||*
     *|||||||||*
    *|||||||||||*
   *|||||||||||||*
  *|||||||||||||||*
 *|||||||||||||||||*

Code Explanation

1. The program starts with the class declaration public class PatternChristmasTree.
2. Inside the class, the main method is defined as public static void main(String[] args).
3. A variable n is declared and initialized to 10. This variable determines the height of the tree.
4. Three variables i, j, and k are declared.
5. A for loop is used to iterate from 0 to n-1 (inclusive) using the variable i. This loop prints each row of the tree.
6. For each row, an inner for loop is used to print spaces before the star symbol. The loop uses the variable j to print n-i spaces.
7. After the spaces, a star symbol is printed using System.out.print("*").
8. Another inner for loop is used to print | characters on the left side of the tree. The loop uses the variable k to print i-1 | characters.
9. A third inner for loop is used to print | characters on the right side of the tree. The loop uses the variable j to print i-1 | characters.
10. After the | characters, a star symbol is printed on the right side of the tree if the current row is not the top row. This is checked using an if statement that tests if i > 0.
11. Finally, a newline character is printed using System.out.println() to move to the next row of the tree.
12. After the for loop ends, the main method ends and the program terminates.