Justify text in Java

Question

I have to read in an integer which will be the length of the succeeding lines. (The lines of text will never be longer than the length provided).

I then have to read

Answer 1

I had to do something similar to this in Java recently. The code itself is relatively straightforward. What I found took the longest, was getting my head around the justification process.

I started by making a step by step process of how I would justify text manually.

1. Find out how long the line is
2. Find out how long the string is which is on said line
3. Calculate the number of spaces required to add to the string to equal the line length
4. Find out how many gaps there are between the words in the string
5. Calculate how many spaces to add to each gap in the string
6. Add result to each gap
7. Calculate how many extra spaces there are to serially add to each gap (if the number of gaps is not divisible by the number of spaces to add. For example if you have 5 gaps but 6 spaces to add)
8. Add extra spaces to gaps
9. Convert spaces to underscores
10. Return string

Doing this made coding the algorithm much simpler for me!

Finding out how long the line and the string on said line are

You said you have read in the line length and the text on the line so 1 and 2 you have already done. With 2 being a simple string.length() call.

Calculating the number of spaces required to add to the string to equal the line length is simply taking the line length and subtracting the length of the string.

lineLength - string.length() = noofspacestoadd;

Finding out how many gaps there are between all the words in the string

There is probably more than one way of doing this. I found that the easiest way of doing this was converting the string into a char[] and then iterating through the characters checking for ' ' and setting a count for when it does find a ' '

Calculating how many spaces to add to each gap

This is a simple division calculation!

noofgaps / noofspacestoadd = noofspacestoaddtoeachgap;

Note: You have to make sure you're doing this division with integers! As 5 / 2 = 2.5, therefore you KNOW you have to add 2 spaces to each gap between the words, and divisions using int's truncates the decimal number to form an integer.

Add the result to each gap

Before being able to add the number of strings required to add to each gap, you need to convert this number into a string of spaces. So you need to write a method for converting a given integer into a string of spaces equating to that given number. Again, this can be done in different ways. The way I did it was something like this

String s = "";
for(int i=noofspacestoaddtoeachgap; i>0; i--)
{
    s+= " ";
}

return s;

The way I did this was to convert the string into an array of substrings, with the substrings being each word in the array. If you look up the String class in the javadoc you should find the methods in the String class you can use to achieve this!

When you have your array of substrings, you can then add the string of spaces to the end of each substring to form your new substring!

Calculating how many extra spaces there are extra

This is again a simple calculation. Using the % operator you can do a remainder division similar to the division we did earlier.

noofgaps % noofspacestoadd = noofspacestoaddtoeachgap;

The result of this calculation gives us the number of extra spaces required to justify the text.

Add the extra spaces serially to each gap

This is probably the most difficult part of the algorithm, as you have to work out a way of iterating through each gap between the words and add an extra space until there are no more extra spaces left to add!

Return string

return String;