Program to Display Hollow square star pattern in Java using loops

import java.util.Scanner;
class Hollow_Rectangle{
public static void main(String args[]){
int size;//declare variable size
    Scanner scan=new Scanner(System.in); 
  //create a scanner object for input
System.out.print("Enter the integer number: ");
size=scan.nextInt();//get input from the user for num1
for (int row=1; row<=size; row++){
  System.out.print("*");
}
System.out.print("\n");
for (int coloum=1; coloum<=size-2; coloum++){
  for (int row=1; row<=size; row++){
  if(row==1||row==size){
    System.out.print("*");
  }else{
    System.out.print(" ");
  }
  
}
  System.out.print("\n");
}
for(int row=1; row<=size; row++){
  System.out.print("*");
}
System.out.print("\n");
}
}

Approach

• The program requests to input for the “size of the pattern”
• The input stores in the variable “size”
• To iterate through the row, run the first for loop from 1 to given size according to the loop structure for (row=1; row<=size; row++) to print star for first-line
• To iterate through the column, run the outer for loop from 1 to given size according to the loop structure for (coloum=1; coloum<=size-2; coloum++)
• Inner for loop print star when the if statement is satisfied if(row==1||row==size) otherwise print space
• This activity continues until the condition of outer while loop becomes false
• Finally, run the last for loop from 1 to given size according to the loop structure for(row=1; row<=size; row++) to print star for the last line

Program 2

This program allows the user to enter the size of the pattern and then it displays Hollow square star pattern using while loop in Java language

import java.util.Scanner;
class Hollow_Rectangle1{
public static void main(String args[]){
int size;//declare variable size
    Scanner scan=new Scanner(System.in); 
  //create a scanner object for input
System.out.print("Enter the integer number: ");
size=scan.nextInt();
//get input from the user for num1
int row=1;
while( row<=size){
  System.out.print("*");
  row++;
}
System.out.print("\n");
int coloum=1; 
while(coloum<=size-2){
  row=1;
  while( row<=size){
  if(row==1||row==size){
    System.out.print("*");
  }else{
    System.out.print(" ");
  }
  row++;
}
  System.out.print("\n");
  coloum++;
}
row=1;
while(row<=size){
  System.out.print("*");
  row++;
}
System.out.print("\n");
}
}

Approach

• The program requests to input for the “size of the pattern”
• The input stores in the variable “size”
• To iterate through the row, run the first for loop from 1 to given size according to the loop structure while( row<=size) to print star for first-line
• To iterate through the column, run the outer for loop from 1 to given size according to the loop structure while(coloum<=size-2)
• Inner while loop print star when the if statements satisfied if(row==1||row==size) otherwise print space
• This activity continues until the condition of outer while loop becomes false
• Finally, run the last for loop from 1 to given size according to the loop structure while( row<=size) to print star for the last line

Program 3

This program allows the user to enter the size of the pattern and then it displays Hollow square star pattern using the do-while loop in Java language

import java.util.Scanner;
class Hollow_Rectangle2{
public static void main(String args[]){
int size;//declare variable size
    Scanner scan=new Scanner(System.in); 
  //create a scanner object for input
System.out.print("Enter the integer number: ");
size=scan.nextInt();
//get input from the user for num1
int row=1;
do{
  System.out.print("*");
  row++;
}while( row<=size);
System.out.print("\n");
int coloum=1; 
do{
  row=1;
  do{
  if(row==1||row==size){
    System.out.print("*");
  }else{
    System.out.print(" ");
  }
  row++;
}while( row<=size);
  System.out.print("\n");
  coloum++;
}while(coloum<=size-2);
row=1;
do{
  System.out.print("*");
  row++;
}while(row<=size);
System.out.print("\n");
}
}