Print Left Triangle Star Pattern in Java

In this article, we will understand how to print the left triangle star pattern using Java. The pattern is formed by using multiple for-loops and print statements.

Problem Statement

Write a program in Java to print the left triangle star pattern. Below is a demonstration of the same ?

Input

Enter the number of rows : 8

Output

*
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *
* * * * * * * *

Different Approaches

Following are the different approaches to print left triangle star pattern ?

• Using user input
• Using predefined input
  

Using user input

Following are the steps to print the left triangle star pattern using user input ?

• First, we will import the Scanner class using java.util package for user input.
  
• After that, we will declare variables i, j, and my_input and create a Scanner object to read the user's input.
• Prompt the user to enter the number of rows and store the input in my_input.
  
• Use a nested loop to print stars ('*'): The outer for loop iterates from 0 to my_input and the inner for loop iterates from 0 to the current row index, printing stars.
• After completing each row, print a new line to move to the next row.
  
• Display the left triangle star pattern.
  

Example

Here, the input is entered by the user based on a prompt ?

import java.util.Scanner;
public class LeftTriangle{
   public static void main(String args[]){
      int i, j, my_input;
      System.out.println("Required packages have been imported");
      Scanner my_scanner = new Scanner(System.in);
      System.out.println("A reader object has been defined ");
      System.out.print("Enter the number of rows : ");
      my_input = my_scanner.nextInt();
      System.out.println("The left triangle star pattern : ");
      for(i=0; i<my_input; i++){
         for(j=0; j<=i; j++){
            System.out.print("* ");
         }
         System.out.println();
      }
   }
}

Output

Required packages have been imported
A reader object has been defined
Enter the number of rows : 8
The left triangle star pattern :
*
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *
* * * * * * * *

Using predefined input

Following are the steps to print the left triangle star pattern using predefined input?

• First, we will declare variables i, j, and my_input.
  
• After that, we will predefine the value of my_input as 8.
  
• Print a message showing the number of rows defined.
  
• Use a nested loop to print stars ('*'): The outer loop iterates from 0 to my_input and the inner loop iterates from 0 to the current row index, printing stars.
• After completing each row, print a new line to move to the next row.
  
• Display the left triangle star pattern.
  

Example

Here, the integer has been previously defined, and its value is accessed and displayed on the console ?

public class LeftTriangle{
   public static void main(String args[]){
      int i, j, my_input;
      my_input = 8;
      System.out.println("The number of rows is defined as " +my_input);
      System.out.println("The left triangle star pattern : ");
      for(i=0; i<my_input; i++){
         for(j=0; j<=i; j++){
            System.out.print("* ");
         }
         System.out.println();
      }
   }
}

Output

The number of rows is defined as 8
The left triangle star pattern :
*
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *
* * * * * * * *