Text formatting: Format one line of text

Solving Sub-problem 2: right-adjust one line of text

Question:

What would you do if someone as you to "right-adjust" a given line ???
Recall the requirements:

To get a sense of the problem, use a concrete example:

Here is a line before the right-adjust operation:
Notice there are 4 space between the end of the line and the right-margin of the text.
Here is a line after the right-adjust operation:
Notice the 4 trailing space are distributed semi-evenly into the gaps in the text.
Question: How would you right-adjust a line ???

Sketch of the algorithm:

S = number of trailing spaces in the line G = number of gaps between the words in the line Distribute S spaces evenly over the G gaps (need refining)

Determining the number of trailing space in the line

This problem is very easy to solve.

Example:

012345678901234567890123456789 >WE hold these Truths to be length of the string "WE hold these Truths to be" = 26 characters

Determine the number of trailing space in the line: line

Determining the number of gaps in the line

Note:
We will use the following class in the Java library to do this job:
Check out the Java documentation page of the StringTokenizer class: click here

Summary of the StringTokenizer class:

The StringTokenizer class breaks a string into tokens that are separated by spaces

The StringTokenizer class contains methods to count the number of tokens (words) and retrieve the tokens (words)

StringTokenizer T = StringTokenizer( SomeString ) will initialize a StringTokenizer object T with the words in the string SomeString.
T.countTokens() returns the number of words in the StringTokenizer object T.
T.nextToken() returns the next word stored inside in the StringTokenizer object T.

Example usage:

StringTokenizer T = new StringTokenizer("Hello, Mr. Smith"); int N = T.countTokens(); // Number of token in the string (= 3) String s; for ( int i = 0; i < N; i++ ) { s = T.nextToken(); // Get next token System.out.println( s ); // Print it }
Will print: Hello, Mr. Smith

Example Program: (Demo above code)
- Prog file: click here
How to run the program:

How to determine the number of gaps in a line using the StringTokenier class:

The number of gaps in a line of text = the number of tokens (words) − 1
Example:

WE hold these Truths to be (6 tokens) ^ ^ ^ ^ ^ 5 gaps (5 = 6 - 1)

Therefore:

StringTokenizer T = new StringTokenizer( line ); G = T.countTokens() - 1; // G = # gaps in line

Distribute S spaces "evenly" over G gaps

First consider 2 examples:

Let's use an analogy to figure out what to do:

Suppose you have 4 bottles of milk and 3 children
You want to distribute (share) the bottless of milk evenly among the children (without opening any bottle of milk)
How many bottles will each child get ?
How to share 8 bottles of milk among 3 children ?
How to share 12 bottles of milk among 3 children ?
How to share 13 bottles of milk among 3 children ?

How to share S bottles of milk among 3 children ?
In general: How to share S bottles of milk among G children ?

Pseudo code: right-justify a line

Refined pseudo code: right-justify a line

NTrailingSpaces = MAXLINELENGTH - line.length() ; // # trailing spaces StringTokenizer T = new StringTokenizer( line ); // Break "line" into tokens NGaps = T.countTokens() - 1; // # gaps between words NSpacesPerGap = NTrailingSpaces / NGaps; NExtra = NTrailingSpaces % NGaps; /* ----------------------------------------------- Construct the right-adjusted line ----------------------------------------------- */ outputLine = T.nextToken( ); // First word for ( k = 1; k <= NGaps; k++ ) { /* ------------------------------------------- Add 1+NSpacesPerGap spaces to a gap ------------------------------------------- */ for (i = 1; i <= 1+NSpacesPerGap; i++) outputLine = outputLine + " "; /* ------------------------------------------- Add 1 more space to the first NExtra gaps ------------------------------------------- */ if (k <= NExtra) outputLine = outputLine + " "; /* ------------------------------------------- Add the next word... ------------------------------------------- */ outputLine = outputLine + T.nextToken(); }

Note:

There are 2 special cases where we do not need to make adjustment to the input line:

Case 1: the input line has the no trailing spaces (i.e., the line is already right-adjusted)
Case 2: the input line contains only one word on the entire line...

How to handle these special cases:

The modified right-adjustment algorithm as a Java Method:

public static String fixLine(String s, int maxLineLength) { int NGaps; int NTrailingSpaces; int NSpacesPerGap; // # spaces to insert in each gap int NExtra; // # gaps that gets ONE extra space String outputLine; // Output string... StringTokenizer T; // Help variables... int i, k; /* ------------------------------------------------- Check if line already fits perfectly.... ------------------------------------------------- */ if ( s.length() == maxLineLength ) return(s); // Already right-justified /* -------------------------------------- Compute: NTrailingSpaces and NGaps -------------------------------------- */ NTrailingSpaces = maxLineLength - s.length(); // # trailing spaces T = new StringTokenizer(s); NGaps = T.countTokens() - 1; // # gaps /* ------------------------------------------------- Check if line has > 1 word.... (Lines with 1 word can't be right-adjusted !) ------------------------------------------------- */ if ( NGaps == 0 ) return( s ); // Can't adjust line, return as is... /* ================== The right adjust line algorithm ============== */ NSpacesPerGap = NTrailingSpaces / NGaps; NExtra = NTrailingSpaces % NGaps; /* ------------------------------------- Construct the right-adjusted line ------------------------------------- */ outputLine = T.nextToken(); // Put first word in output for ( k = 1; k <= NGaps; k++ ) { /* ------------------------------------------- Add 1+NSpacesPerGap spaces to a gap ------------------------------------------- */ for (i = 1; i <= 1+NSpacesPerGap; i++) outputLine = outputLine + " "; /* ------------------------------------------- Add 1 more space to the first NExtra gaps ------------------------------------------- */ if (k <= NExtra) outputLine = outputLine + " "; /* ------------------------------------------- Add the next word... ------------------------------------------- */ outputLine = outputLine + T.nextToken(); } return(outputLine); }

Example Program: (Demo above code)

Prog file: click here
Input file 1 (small): click here
Input file 2 (large): click here

How to run the program:

Right click on link and save in a scratch directory
To compile: javac FormatText3.java
To run: java FormatText3 inp1
Or: java FormatText3 inp2

Example:

Input file 1:

WE hold these Truths to be self-evident, that all Men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the Pursuit of Happiness.

Output:

012345678901234567890123456789 Before:>WE hold these Truths to be After: >WE hold these Truths to be 012345678901234567890123456789 Before:>self-evident, that all Men are After: >self-evident, that all Men are 012345678901234567890123456789 Before:>created equal, that they are After: >created equal, that they are 012345678901234567890123456789 Before:>endowed by their Creator with After: >endowed by their Creator with 012345678901234567890123456789 Before:>certain unalienable Rights, After: >certain unalienable Rights, 012345678901234567890123456789 Before:>that among these are Life, After: >that among these are Life, 012345678901234567890123456789 Before:>Liberty and the Pursuit of After: >Liberty and the Pursuit of 012345678901234567890123456789 Before:>Happiness. After: >Happiness.