用限制和IF语句在Java中打印矩形不起作用

Question

I am trying to create a program that takes user input and makes a rectangle. The user input to numbers for length and width and another symbol or character to fill in the rectangle. That all works fine. My code works for creating a rectangle of any size but I need limit If the no of rows or cols is less than or equal to zero or more than 50 it needs to print out "error in input".

This is the code I have and I am currently trying to define it with if statement and it keeps print the state "error in input and the rectangle. Any help would be appreciated or another method to achieve the same thing.

import java.util.Scanner;

public class Rectangle
  {
    public static void main(String[] args)
  {
 int length;
 int width;
 String symbol;
 char symbolz;
 int xLength;
 int yWidth;



 Scanner input = new Scanner(System.in);         
 while(input.hasNext()){
    {  width = input.nextInt();
       length = input.nextInt();
       symbol = input.next();
       symbolz = symbol.charAt(0);


       if (length<=0||length>50||width<=0||width>50){
       }
        System.out.print("error in input");{

       {for (yWidth = 1; yWidth <= width; yWidth++){
        for (xLength = 1; xLength <= length; xLength++) {
            System.out.print(symbolz);
        }

        System.out.println(" ");
    }
    for(yWidth = 1; yWidth >= width; yWidth--){
        for (xLength = 1; xLength >= length; xLength--){
            System.out.print(symbolz);
        }

        System.out.println(" ");
                }
            }
            }
        }
    }
}}

Edited: switched to if statement but still am having trouble because it keeps inserting "error in user input" in all things typed and also prints the rectangle when it isn't supposed to.

So far I have tried to get the If statement to work and it keeps doing the same thing where it keeps print "error in user input" on inputs that are out side the range but it also prints the rectangle after which it shouldn't do. Any guidance?

Answer 1

The construct is called a do-while, and the general format is:

do {
    // statements
} while (condition);

Your do loop is missing the while (condition) which indicates when the loop should stop.

It's essentially a while loop, with the difference being that with do-while, condition is tested at the end of the loop, where with a while loop, it's tested at the start, so a do-while will always execute the loop at least once.

Answer 2

I got it to work with a if and continue statement.

import java.util.Scanner;

public class Rectangle
 {
 public static void main(String[] args)
 {
 int length;
 int width;
 String symbol;
 char symbolz;
 int xLength;
 int yWidth;



 Scanner input = new Scanner(System.in);
 while(input.hasNext()){
    {  width = input.nextInt();
       length = input.nextInt();
       symbol = input.next();
       symbolz = symbol.charAt(0);
       if (length<=0||length>50||width<=0||width>50){
       System.out.print("error in input");
       System.out.println();
       continue;}
   {
       for (yWidth = 1; yWidth <= width; yWidth++){
            for (xLength = 1; xLength <= length; xLength++) {
                System.out.print(symbolz);

    }

    System.out.println(" ");
}
for(yWidth = 1; yWidth >= width; yWidth--){
    for (xLength = 1; xLength >= length; xLength--){
         System.out.print(symbolz);
    }

    System.out.print(" ");
            }
        }
        }
    }
}

}

Answer 3

Error is here :

  if (length<=0||length>50||width<=0||width>50){
       }    // --> Error: if input outside range then we have to use continue or exit.
        System.out.print("error in input");{   // Message must be in previous if 

use This:

  if((length<=0 || length >50) || (width<=0 || width>50))
       {
         System.out.println("Error in input");
       } 

Hope this may solve your problem.