String,number,String+number的Comparator排序

    这个比较器写的比较好,多种数据形式也能比对排序。

package code;

import java.util.*;

public class IntuitiveStringComparator<T extends CharSequence> implements
		Comparator<T> {
	private T str1, str2;
	private int pos1, pos2, len1, len2;

	public int compare(T s1, T s2) {
		str1 = s1;
		str2 = s2;
		len1 = str1.length();
		len2 = str2.length();
		pos1 = pos2 = 0;

		if (len1 == 0) {
			return len2 == 0 ? 0 : -1;
		} else if (len2 == 0) {
			return 1;
		}

		if (isNumeric(str1.toString()) && isNumeric(str2.toString())) {
			// System.out.println("test ");
			if (Double.parseDouble(str1.toString()) > Double.parseDouble(str2
					.toString())) {
				return 1;
			} else {
				return -1;
			}

		}else {
			while (pos1 < len1 && pos2 < len2) {
				char ch1 = str1.charAt(pos1);
				char ch2 = str2.charAt(pos2);
				int result = 0;

				if (Character.isDigit(ch1)) {
					result = Character.isDigit(ch2) ? compareNumbers() : -1;
				} else if (Character.isLetter(ch1)) {
					result = Character.isLetter(ch2) ? compareOther(true) : 1;
				} else {
					result = Character.isDigit(ch2) ? 1 : Character
							.isLetter(ch2) ? -1 : compareOther(false);
				}

				if (result != 0) {
					return result;
				}
			}

		}

		return len1 - len2;
	}

	private int compareNumbers() {
		int delta = 0;
		int zeroes1 = 0, zeroes2 = 0;
		char ch1 = (char) 0, ch2 = (char) 0;

		// Skip leading zeroes, but keep a count of them.
		while (pos1 < len1 && (ch1 = str1.charAt(pos1++)) == '0') {
			zeroes1++;
		}
		while (pos2 < len2 && (ch2 = str2.charAt(pos2++)) == '0') {
			zeroes2++;
		}

		// If one sequence contains more significant digits than the
		// other, it's a larger number. In case they turn out to have
		// equal lengths, we compare digits at each position; the first
		// unequal pair determines which is the bigger number.
		while (true) {
			boolean noMoreDigits1 = (ch1 == 0) || !Character.isDigit(ch1);
			boolean noMoreDigits2 = (ch2 == 0) || !Character.isDigit(ch2);

			if (noMoreDigits1 && noMoreDigits2) {
				return delta != 0 ? delta : zeroes1 - zeroes2;
			} else if (noMoreDigits1) {
				return -1;
			} else if (noMoreDigits2) {
				return 1;
			} else if (delta == 0 && ch1 != ch2) {
				delta = ch1 - ch2;
			}

			ch1 = pos1 < len1 ? str1.charAt(pos1++) : (char) 0;
			ch2 = pos2 < len2 ? str2.charAt(pos2++) : (char) 0;
		}
	}

	private int compareOther(boolean isLetters) {
		char ch1 = str1.charAt(pos1++);
		char ch2 = str2.charAt(pos2++);

		if (ch1 == ch2) {
			return 0;
		}

		if (isLetters) {
			ch1 = Character.toUpperCase(ch1);
			ch2 = Character.toUpperCase(ch2);
			if (ch1 != ch2) {
				ch1 = Character.toLowerCase(ch1);
				ch2 = Character.toLowerCase(ch2);
			}
		}

		return ch1 - ch2;
	}

	public boolean isNumeric(String str12) {
		// String str12 = str1.toString();
		try {
			double d = Double.parseDouble(str12);
		} catch (NumberFormatException nfe) {
			return false;
		}
		return true;

		// return str12.matches("-?\\d+(\\.\\d+)?"); //match a number with
		// optional '-' and decimal.
	}

	public static void main(String[] args) {
		String[] list = { "foo 03", "foo 00003", "foo 5", "foo 003", "foo~03",
				"foo 10far", "foo 10boo", "2", "0.5", "foo 10", "-20", "1.1", "foo!03",
					 "1.0", "10000", "20", ".7","-40"

		};

		Arrays.sort(list, new IntuitiveStringComparator<String>());
		for (String s : list) {
			System.out.println(s);
		}
	}
}

运行结果如下：

-40
-20
0.5
.7
1.0
1.1
2
20
10000
foo 03
foo 003
foo 00003
foo 5
foo 10
foo 10far
foo 10boo
foo!03
foo~03

即使小数点前没有零也能正常排序。