Java Program to Print Square Star Pattern

13 Jan, 2022
Here, we will implement a Java program to print the square star pattern. We will print the square star pattern with diagonals and without diagonals. 
Example:
**********************
*                    *
*                    *
*                    *
*                    *
*                    *
*                    *
**********************
Approach:
Step 1: Input number of rows and columns.
Step 2: For rows of rectangle run the outer loop from 1 to rows.
for (i = 1; i < = rows; i++)
Step 3: For the column of the rectangle run the inner loop from 1 to columns.
for (j = 1; j < = columns; j++)
Step 4: Print star for first or last row or for first or last column, otherwise print blank space.
Step 5: After printing all columns of a row, print the newline after the inner loop.
Example 1: Star square pattern without diagonals
Java
// Java Program to Print Square Pattern// Case 1: Hollow rectangle // Importing input output classesimport java.io.*; // Main classclass GFG {     // Method 1    // To print hollow rectangle    static void print_rectangle(int k, int l)    {        int a, b;         // Nested for loops for iterations         // Outer loop for rows        for (a = 1; a <= k; a++) {            // Inner loop for columns            for (b = 1; b <= l; b++) {                // Condition check using logical OR operator                // over rows and columns positions                // if found at circumference of rectangle                if (a == 1 || a == k || b == 1 || b == l)                     // Print the star pattern                    System.out.print("*");                else                     // Rest inside square print the empty                    // spaces                    System.out.print(" ");            }             // By now we are done with only 1 row so            // New line            System.out.println();        }    }     // Method 2    // Main driver method    public static void main(String args[])    {        // Declaring and initializing rows and columns        // For square row = columns         // Custom input initialization values        int rows = 8, columns = 22;         // Calling the method1 to print hollow rectangle        // pattern        print_rectangle(rows, columns);    }}
**********************
*                    *
*                    *
*                    *
*                    *
*                    *
*                    *
**********************
Now taking it a step further as in above we simply inserted empty spaces inside the rectangle. In mathematics, we already have come across diagonals, so we can print them too in the above case.
Example 2: Star square pattern with diagonals 
Java
// Java Program to Print Square Star pattern// Case: Primary and secondary diagonal Rectangle Patternimport java.io.*; // Mai classclass GFG {     // Method 1    // To print square with primary and secondary diagonal    static void print_squaredi(int k)    {        int a, b;         // Nested 2 for loops for Matrix printing         // Outer loop for rows        for (a = 1; a <= k; a++) {            // Inner loop for columns            for (b = 1; b <= k; b++) {                // Condition check using OR operator where                // 1. Printing star as per first 4 checks                // on the circumference of rectangle                // 2. Fifth check is for diagonals                if (a == 1 || a == k || b == 1 || b == k                    || a == b || b == (k - a + 1))                     // Print the star pattern                    System.out.print("*");                else                     // Print the white spaces                    System.out.print(" ");            }             // By now we are over with one row so            // new line            System.out.println();        }    }     // Method 2    // Main driver method    public static void main(String args[])    {        // This time taking square so only one variable        // needs to be declared        // Custom input entry        int rows = 12;         // calling the method1 to print        // square pattern with diagonal        print_squaredi(rows);    }}
************
**        **
* *      * *
*  *    *  *
*   *  *   *
*    **    *
*    **    *
*   *  *   *
*  *    *  *
* *      * *
**        **
************
 
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surinderdawra388
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