A Programmer[ap]s Guide to Java Certification

/** * Aggregate pairs of arbitrary objects. */ public final class Pair { private Object first, second; /** Construct a Pair object. */ public Pair(Object one, Object two) { first = one; second = two; } /** Provides access to the first aggregated object. */ public Object getFirst() { return first; } /** Provides access to the second aggregated object. */ public Object getSecond() { return second; } /** @return true if the pair of objects are identical. */ public boolean equals(Object other) { if (! (other instanceof Pair)) return false; Pair otherPair = (Pair) other; return first.equals(otherPair.getFirst()) && second.equals(otherPair.getSecond()); } /** @return a hash code for the aggregate pair. */ public int hashCode() { // XORing the hash codes to create a hash code for the pair. return first.hashCode() ^ second.hashCode(); } /** @return the textual representation of aggregated objects. */ public String toString() { return "[" + first + "," + second + "]"; } }

public class Palindrome { public static void main(String[] args) { if (args.length != 1) { System.out.println("Usage: java Palindrome <word>"); return; } String word = args[0]; StringBuffer reverseWord = new StringBuffer(word); reverseWord.reverse(); boolean isPalindrome = word.equals(reverseWord.toString()); System.out.println("The word " + word + " is " + (isPalindrome ? "" : "not ") + "a palindrome"); } }