Java程序未打印我的所有打印语句

Question

In my computer science class we were asked to create a program that would prompt the user to enter how many rows, columns, and what symbol they would like printed in a "magic box" and to store each of these variables and print them their very own magic box using a nested for loop. My program compiles properly and prints the correct box based on my inputs, but it does not print two of my print statements. It will print the first three statements (the ones prompting the user to enter certain things), but does not print the statements

Here comes the magic...Here's your very own magic box

and

This magic box brought to you by Beth Tanner."

I have tried everything I can think of and still cannot get these statements to print, any help would be greatly appreciated. I am including my program below.

import java.util.Scanner;

public class MagicBox {
  public static void main(String[] args) {
    Scanner input= new Scanner(System.in);

    System.out.println("How many rows would you like in your box?");
      int rows = input.nextInt();
    System.out.println("How many columns would you like in your box?");
      int columns = input.nextInt();
    System.out.println("What symbol would you like in your box?");
      String symbol = input.next(); 

    System.out.println("Here comes the magic...\nHere's your very own magic box!");

    int count1;
    int count2;
      for(count1 = 1; count1 <= rows; count1++) 
        for (count2 = 1; count2 <= columns; count2++)
          System.out.print(symbol);
          System.out.println(); 
      System.out.println("This magic box brought to you by Beth Tanner.");   

  } // end main
} // end class

Answer 1

Using correct blocks, everything works.

Note that the outer loop must enclose the newline produced by System.out.println(); . In your code this newline is only printed afer all row * columns symbols have been printed on one line.

int rows = 5;
int columns = 3;
String symbol = "@";

System.out.println("Here comes the magic...\nHere's your very own magic box!");

for (int count1 = 1; count1 <= rows; count1++) {
    for (int count2 = 1; count2 <= columns; count2++) {
        System.out.print(symbol);
    }
    System.out.println();
}

System.out.println("This magic box brought to you by Beth Tanner.");

Output:

Here comes the magic...
Here's your very own magic box!
@@@
@@@
@@@
@@@
@@@
This magic box brought to you by Beth Tanner.

Answer 2

I have no idea what Magic box is, but I assume you want something like this:

for(count1 = 1; count1 <= rows; count1++) {
    for (count2 = 1; count2 <= columns; count2++) {
      System.out.print(symbol);
    }
    System.out.println();
  }

There are a couple of problems with your initial code:

• There is no "collumns" variable declared - you have a typo there and it's actually columns
• Always use curly braces in loops. Without those you only one expression will be executed in each loop, which means that System.out.println() will only be invoked once as opposed to being added after every row.

Answer 3

I think you want this:

for(count1 = 1; count1 <= rows; count1++){ 
  for (count2 = 1; count2 <= columns; count2++)
    System.out.print(symbol);

  System.out.println(); 
}

or even clearer

for(count1 = 1; count1 <= rows; count1++){ 
  for (count2 = 1; count2 <= columns; count2++){
    System.out.print(symbol);
  }

  System.out.println(); 
}

This will give you the magic box you desire.

This link may help you see the difference: stackoverflow question on omitting braces