Java中具有不同字符的空心正方形

Question

So i have been tasked with creating a hollow square which basically needs to look like this.

*----*
|    |
|    |
|    |
*----*

(size varying on user input) The user is supposed to input width and length. As for now i've been able to create a hollow square and a full square and everything. Now i'm just realy stumped towards how i can create the square with the different characters..

import java.util.Scanner;
public class HulR{
  public static void main (String []args) {
 Scanner tastatur = new Scanner(System.in) ;

 int bredde;
 int lengde;


 System.out.print("bredde") ; 
 bredde = tastatur.nextInt();

 System.out.print("lengde"); 
 lengde = tastatur.nextInt();

 for (int j = 1; j<= bredde; j++) 
   for (int i = 1; i <= lengde; i++){
     if (i == 1 || i == lengde) 
       System.out.print("*");

     else 
       System.out.print("|");
System.out.println();
 }  

This is how far i've come.. i'm 3 weeks into a beginners course for programming and i'm just lost when it comes to this task..

bredde = width and lengde = length btw

Answer 1

Think about it: you are printing it line by line.

The first and last line are different from the "middle" ones in that they are of the form --- , while the other are in the form | |.

So we must differentiate between these two cases:

for (int i = 1; i<=height; i++) {
   for (int j = 1; j<=width; j++) {
     if (isFirstOrLastLine(i, height)) {
        //print like this: *--*
     }
     else {
        //print like this : |  |
     }
   }
}

Now, how do we know if we are on the first or last line:

boolean isFirstOrLastLine(int line, int height) {
  return i == 1 || i == height;
}

Now we can fill in the logic to print the actual line!

for (int i = 1; i<=height; i++) {
   for (int j = 1; j<=width; j++) {
     if (isFirstOrLastLine(i, height)) {
        //print like this: *--*
        if (isFirstOrLastColumn(j, width)) {
           System.out.print("*");
        }
        else {
           System.out.print("-");
        }
     }
     else {
        //print like this : |  |
        if (isFirstOrLastColumn(j, width)) {
           System.out.print("|");
        }
        else {
           System.out.print(" ");
        }
     }
   }
}

Can you guess the code for the "isFirstOrLastColumn" function yourself?

Answer 2

Here is a pretty solution for the problem:

Code :

import java.util.Arrays;
import java.util.Scanner;

public class Program {
    public static void main(String[] args) {
        // query parameters
        Scanner in = new Scanner(System.in);

        System.out.print("width=");
        int width = in.nextInt();

        System.out.print("height=");
        int height = in.nextInt();

        // setup model
        char[] headline = new char[width];
        Arrays.fill(headline, '-');
        headline[0] = '*';
        headline[width - 1] = '*';

        char[] midline = new char[width];
        Arrays.fill(midline, ' ');
        midline[0] = '|';
        midline[width - 1] = '|';

        // draw model
        System.out.println(headline);
        if (height >= 2) {
            for (int r = 1; r < height - 1; r++) {
                System.out.println(midline);
            }
            System.out.println(headline);
        }
    }
}

---

width and height are assumed to be greater than 0, feel free to add code to handle incorrect user input.