In this article, we are going to learn how to print diamond shape star patterns in Java.
Illustration:
Input: number = 7
Output:
*
***
*****
*******
*********
***********
*************
***********
*********
*******
*****
***
*
Methods: When it comes to pattern printing we do opt for standard ways of printing them via loops only. We will try out different types of loops to print the same pattern.
Example 1: Using do-while Loop
Java
// Java program to Print Diamond Star Pattern// Using do-while loop// Importing input output classesimport java.io.*;// Main classpublic class GFG { // Main driver method public static void main(String[] args) { // Declaring and initializing variables // Variable initialized to the row where max star // should be there as after that they decreases to // give diamond pattern int number = 7; // Diamond starting with single star in first row,so // initialized int m = 1; // Columnar printing int n; // Outer loop 1 // Prints the first half diamond do { n = 1; // Inner loop 1 // Prints space until ++n <= number - m + 1 is // false do { // Print whitespace between System.out.print(" "); } // Condition for inside do-while loop 1 while (++n <= number - m + 1); // Now n = 1; // Inner loop 2 // Prints star until ++n <= m * 2 - 1 is false do { // Print star System.out.print("*"); } // Condition for inner do-while loop 2 while (++n <= m * 2 - 1); // A new row requires a new line System.out.println(); } // Condition for outer do-while loop 1 while (++m <= number); // Now we are done with printing the upper half // diamond. // Note: Not to print the bottom row again in lower // half diamond printing Hence variable to be // initialized should one lesser than number m = number - 1; // Outer loop 2 // Prints the second half diamond do { n = 1; // Inner loop 1 // Prints space until ++n <= number - m + 1 is // false do { // Print whitespace between System.out.print(" "); } while (++n <= number - m + 1); n = 1; // Inner loop 2 // Prints star until ++n <= m * 2 - 1 is false do { // Prints star System.out.print("*"); } while (++n <= m * 2 - 1); // By now done with one row of lower diamond // printing so a new line is required System.out.println(); } // Condition for outer do-while loop 2 while (--m > 0); }} |
Output
*
***
*****
*******
*********
***********
*************
***********
*********
*******
*****
***
*
Time complexity: O(n^2) where n is given input number
Auxiliary Space: O(1)
Example 2: Using while Loop
Java
// Java program to print diamond star pattern// Using while loop// Importing input output classesimport java.io.*;// Main classpublic class GFG { // Main driver method public static void main(String[] args) { // Declaring and initializing variables // Variable initialized to the row where max star // should be there as after that they decreases to // give diamond pattern int number = 7; // Diamond starting with single star in first row int m = 1; // Columnar printing int n; // Outer loop 1 // Prints the first half diamond // Condition holding true till // number of rows initialized while (m <= number) { n = 1; // Inner loop 1 // Prints space until n++ <= number - m is false while (n++ <= number - m) { // Print whitespaces inbetween System.out.print(" "); } n = 1; // Inner loop 2 // Prints star until n++ <= m * 2 - 1 is false while (n++ <= m * 2 - 1) { // Print star System.out.print("*"); } // By now we are done for above pyramid printing // ending line after each row System.out.println(); // Incrementing as we want pyramid generation m++; } // Now we are done with printing the upper half // diamond. // Note: Not to print the bottom row again in lower // half diamond printing Hence variable t be // initialized should one lesser than number m = number - 1; // Outer loop 2 // Prints the second half diamond while (m > 0) { n = 1; // Inner loop 1 // Prints spaces until n++ <= number - m is // false while (n++ <= number - m) { // Print whitespace in between System.out.print(" "); } n = 1; // Inner loop 2 // Prints star until n++ <= m * 2 - 1 is false while (n++ <= m * 2 - 1) { // Print star System.out.print("*"); } // Ending line after each row System.out.println(); // Decrementing as we want reverse pyramid // generation m--; } }} |
Output
*
***
*****
*******
*********
***********
*************
***********
*********
*******
*****
***
*
Example 3: Using for Loop
Java
// Java program to print diamond star pattern// Using for loop// Importing input output classesimport java.io.*;// Main classpublic class GFG { // Main driver method public static void main(String[] args) { // Declaring and initializing variables // Variable initialized to the row where max star // should be there as after that they decreases to // give diamond pattern int number = 7; int m, n; // Outer loop 1 // prints the first half diamond for (m = 1; m <= number; m++) { // Inner loop 1 print whitespaces inbetween for (n = 1; n <= number - m; n++) { System.out.print(" "); } // Inner loop 2 prints star for (n = 1; n <= m * 2 - 1; n++) { System.out.print("*"); } // Ending line after each row System.out.println(); } // Outer loop 2 // Prints the second half diamond for (m = number - 1; m > 0; m--) { // Inner loop 1 print whitespaces inbetween for (n = 1; n <= number - m; n++) { System.out.print(" "); } // Inner loop 2 print star for (n = 1; n <= m * 2 - 1; n++) { System.out.print("*"); } // Ending line after each row System.out.println(); } }} |
Output
*
***
*****
*******
*********
***********
*************
***********
*********
*******
*****
***
*
Time Complexity : O(n2)
Auxiliary Space : O(1)
