Implementing a word-chain checker

This is web exercise 3.1.45. from the book Computer Science An Interdisciplinary Approach by Sedgewick & Wayne:

Write a program that reads in a list of words from the command line
and prints true if they form a word chain and false otherwise. In a
word chain, adjacent words must differ in exactly one letter, e.g.,

Here is my program:

public class WordChainChecker 
    public static boolean checkWordCouple(String word1, String word2)
        int counter = 0;
        int wordLength = word1.length();
        for (int i = 0; i < wordLength; i++)
            if (word1.charAt(i) != word2.charAt(i)) counter++;
        if (counter > 1) return false;
        else             return true;
    public static void main(String() args)
        String word1 = StdIn.readString();
        String word2 = StdIn.readString();
        boolean truth = true && checkWordCouple(word1,word2);
        while (!StdIn.isEmpty())
            word1 = StdIn.readString();
            truth = truth && checkWordCouple(word1,word2);
            word2 = word1; 

StdIn is a simple API written by the authors of the book. I checked my program and it works.

Is there any way that I can improve my program?

Thanks for your attention.