Java - print box around contents of a file

I am trying to print the contents of a file surrounded by a box using a method that accepts two parameters: a Scanner representing an input file, and an integer representing the length of the longest line of input in that file. I have most of the box ready but not sure how to place the closing pipes for the right side of the box. This is the bit I don't know how to fix:

int i = length - line.length();        
for (int j = 0; j <= i; j++) {
   System.out.print(" ");
}         
System.out.print("|"); */ 

This is the method I'm using:

public static void printBox(Scanner input, int length) {
	
    int top = 0;
    int bottom = 0;
    System.out.print("+");
    while (top < length + 2) {
        System.out.print("-");
        top++;
    }
    System.out.print("+");
    System.out.println();
    
    
    while (input.hasNextLine()) {
        String line = input.nextLine();
        System.out.println("| " + line);
        
        /* int i = length - line.length();        
        for (int j = 0; j <= i; j++) {
           System.out.print(" ");
        }         
        System.out.print("|"); */ 
    }
    
    System.out.print("+");
    while (bottom < length + 2) {
        System.out.print("-");
        bottom++;
    }
    System.out.print("+");
}

Here is one test case
printBox(new Scanner("This is some\ntext here."), 12);

Without the for loop, I'm getting the following.

+--------------+
| This is some 
| text here.   
+--------------+

And this with the for loop

+--------------+
| This is some
 || text here.
   |+--------------+

The issue here is the difference between your use of System.out.print and System.out.println. println adds a \n new line at the end of your output. I switched two of your print functions and it works as desired.

public static void printBox(Scanner input, int length) {
    int top = 0;
    System.out.print("+");
    while (top < length + 2) {
      System.out.print("-");
      top++;
    }
    System.out.print("+");
    System.out.println();

    while (input.hasNextLine()) {
      String line = input.nextLine();
      System.out.print("| " + line);

      int i = length - line.length();
      for (int j = 0; j <= i; j++) {
        System.out.print(" ");
      }
      System.out.println("|");
    }

    System.out.print("+");
    int bottom = 0;
    while (bottom < length + 2) {
      System.out.print("-");
      bottom++;
    }
    System.out.print("+");
  }

Output:

+--------------+
| This is some |
|  text here.  |
+--------------+

Also a good tip, I moved the declaration/initialization of int bottom to just before its first usage. This is good form based on Checkstyle VariableDeclarationUsageDistance.

1. The for loop code that you commented is perfect as it is adding the extra white space to the desired length before the right vertical line.
   Except for the fact that you are using println before the for loop starts which is causing the spaces to be added in the next line and not in continuation.

2. Also instead of using top and bottom twice to print same horizontal lines. You can use reuse the line created above to be used to close the input.
   Additionally you can use StringBuilder instead of using too many Sysout and string concatenation because that is not memory/space efficient.

Below is an optimised code with all the above suggestions.

public static void printBox(Scanner input, int length) {
    int top = 0;
    StringBuilder line = new StringBuilder();
    line.append('+');
    while (top < length + 2) {
        line.append("-");
        top++;
    }
    line.append("+");
    System.out.println(line);

    while (input.hasNextLine()) {
        String innerLineStr = input.nextLine();
        StringBuilder innerline = new StringBuilder(innerLineStr);
        innerline.insert(0,"| ");

        int i = length - innerLineStr.length();
        for (int j = 0; j <= i; j++) {
            innerline.append(" ");
        }
        innerline.append("|");
        System.out.println(innerline);
    }

    System.out.println(line);
}