anagram.java

初期JAVA学习非常有用的资料。帮助深入了解API。特别是Applet。

/** 
 * This class compiles with v 1.2 and 1.3, but not previous
 * versions, because its sort method uses the Arrays class,
 * which was added in 1.2.  To make Anagram work with early
 * versions of the Java platform, you need to reimplement
 * the sort method. 
 */

public class Anagram {

    /**
     * Tests whether the passed-in strings are anagrams --
     * containing the exact same number of each letter.
     * Punctuation, case, and (obviously) order don't matter.
     * 
     * @return true if the strings are anagrams; otherwise, false
     */
    public static boolean areAnagrams(String string1,
                                      String string2) {

        String workingCopy1 = removeJunk(string1);
        String workingCopy2 = removeJunk(string2);

	workingCopy1 = workingCopy1.toLowerCase();
	workingCopy2 = workingCopy2.toLowerCase();

	workingCopy1 = sort(workingCopy1);
	workingCopy2 = sort(workingCopy2);

        return workingCopy1.equals(workingCopy2);
    }

    /**
     * Removes punctuation, spaces -- everything except letters
     * and digits from the passed-in string.
     * 
     * @return a stripped copy of the passed-in string
     */
    protected static String removeJunk(String string) {
        int i, len = string.length();
  	StringBuffer dest = new StringBuffer(len);
	char c;

	for (i = (len - 1); i >= 0; i--) {
	    c = string.charAt(i);
	    if (Character.isLetterOrDigit(c)) {
		dest.append(c);
	    }
	}

        return dest.toString();
    }

    /** 
     * Sorts the passed-in string.  Reimplement this method
     * if you want to use this class in pre-Java-2 versions
     * of the platform.
     * 
     * @return a sorted copy of the passed-in string
     */
    protected static String sort(String string) {
	int length = string.length();
        char[] charArray = new char[length];

	string.getChars(0, length, charArray, 0);

	//NOTE: The following line of code causes pre-1.2
	//compilers to choke.
	java.util.Arrays.sort(charArray);

        return new String(charArray);
    }

    public static void main(String[] args) {
        String string1 = "Cosmo and Laine:";
        String string2 = "Maid, clean soon!";

        System.out.println();
        System.out.println("Testing whether the following "
                         + "strings are anagrams:");
        System.out.println("    String 1: " + string1);
        System.out.println("    String 2: " + string2);
        System.out.println();

        if (areAnagrams(string1, string2)) {
            System.out.println("They ARE anagrams!");
        } else {
            System.out.println("They are NOT anagrams!");
        }
        System.out.println();
    }
}