J2SE基础/字符串相关

 

/**
	 * 反转字符串
	 * eg:"abc" => "cba"
	 * @param str
	 */
	static void reverseString(String str) {
		// 目标字符串转换为字符数组
		char[] charArray = str.toCharArray();
		// 获取转换后的字符数组长度
		int charLength = charArray.length;
		char char_temp;// 临时字符变量
		// 反转后的字符串
		String newStr;
		// 循环反转字符
		for (int i = 0; i < charLength / 2; i++) {
			// 将索引[i]元素的值赋值临时字符
			char_temp = charArray[i];
			// 索引[charLength - 1 - i]元素的值赋值索引[i]
			charArray[i] = charArray[charLength - 1 - i];
			// 临时字符赋值索引[charLength - 1 - i]元素
			charArray[charLength - 1 - i] = char_temp;
		}
		// 获取反转后的字符串
		newStr = String.valueOf(charArray);
		// CSharp:newStr = new string(charArray);
		// js:newStr = str.split("").reverse().join("");
		System.out.println(newStr);
	}

	static void reverseString2(String str) {
		int length = str.length();
		StringBuilder sb = new StringBuilder(length);
		length--;
		for (int i = length; i >= 0; i--) {
			sb.append(str.charAt(i));
		}
		System.out.println(sb.toString());
	}

/**
	 * 两字符串求最长公共字符串
	 * 
	 * @param a
	 * @param b
	 */
	static void compareString(String a, String b) {
		int beginIndex = 0;
		int endIndex = 0;
		int maxLength = 0;
		String shortString = null;
		String longString = null;
		if (a.length() > b.length()) {
			shortString = b;
			longString = a;
		} else {
			shortString = a;
			longString = b;
		}
		String splitString = null;
		for (int i = 0; i <= shortString.length(); i++) {
			for (int j = i + 1; j <= shortString.length(); j++) {
				splitString = shortString.substring(i, j);
				if (longString.indexOf(splitString) > -1) {
					if (splitString.length() > maxLength) {
						maxLength = splitString.length();
						beginIndex = i;
						endIndex = j;
					}
				}
			}
		}
		System.out.println(String.format("The MaxLength:%d", maxLength));
		System.out.println(String.format("The BeginIndex:%d", beginIndex));
		System.out.println(String.format("The EndIndex:%d", endIndex));
		System.out.println(String.format("The MaxString:%s",
				a.substring(beginIndex, endIndex)));
	}

	/*
	 * 判断回文数
	 */
	static void isPalindrome(String str) {
		boolean sign = true;
		int length = str.length();
		int start = 0;
		int end = 0;
		if (length == 1)
			sign = false;
		for (int i = 0; i < length / 2; i++) {
			start = str.charAt(i);
			end = str.charAt(length - i - 1);
			if ((start ^ end) != 0)
				sign = false;
			// return
		}
		System.out.println(String.format("isPalindrome: %s", sign));
	}

	/*
	 * 判断某一字符串是否与另一字符串相同
	 */
	static void isAnagrams(String a, String b) {
		int aLength = a.length();
		int bLength = b.length();
		int aChar = 0;
		int bChar = 0;
		boolean sign = true;
		int result = 0;
		if (aLength != bLength)
			sign = false;
		// return
		for (int i = 0; i < aLength; i++) {
			aChar = a.charAt(i);
			bChar = b.charAt(i);
			result ^= aChar ^ bChar;
		}
		sign = result == 0;
		System.out.println(String.format("isAnagrams: %s", sign));
	}

	/*
	 * 截取中英文混合的字符串
	 */
	static void subString(String str, int maxLen) {
		int len = 0;
		char cha = '0';
		StringBuilder sb = new StringBuilder(maxLen);
		if (str == null || str.isEmpty())
			return;
		try {
			for (int i = 0; i < str.length(); i++) {
				cha = str.charAt(i);
				len += String.valueOf(cha).getBytes("GBK").length;
				if (len > maxLen)
					break;
				sb.append(cha);
			}
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		System.out.println(sb.toString());
	}

	/*
	 * 汉字九九乘法表
	 */
	static void multiplicationTable() {
		char[] chars = { '零', '一', '二', '三', '四', '五', '六', '七', '八', '九', '十' };
		int result = 0;
		for (int i = 1; i <= 9; i++) {
			for (int j = 1; j <= i; j++) {
				result = i * j;
				if (String.valueOf(result).length() == 1) {
					System.out.print(String.format("  %s×%s=%s  ", chars[i],
							chars[j], chars[result]));
				} else {
					if (result % 10 == 0) {
						System.out.print(String.format("  %s×%s=%s%s  ",
								chars[i], chars[j], chars[(result / 10)],
								chars[10]));
					} else {
						System.out.print(String.format("  %s×%s=%s%s%s  ",
								chars[i], chars[j], chars[(result / 10)],
								chars[10], chars[(result % 10)]));
					}
				}
			}
			System.out.println();
		}
	}

	/*
	 * 模拟手算加法实现大数字计算
	 */
	static String addString(String a, String b) {
		// 判断是否为null
		if (a == null || b == null)
			return null;
		String _a = a.trim();
		String _b = b.trim();
		// 判断是否为空
		if (_a.isEmpty() && _b.isEmpty())
			return null;
		// 判断是否为0
		if (_a.equals("0"))
			return _b;
		if (_b.equals("0"))
			return _a;
		// 判断是否为数字
		if (!(StringUtils.isNumber(a) && StringUtils.isNumber(b)))
			return null;
		// 不足位补零
		if (_a.length() > _b.length()) {
			String temp = _a;
			_a = _b;
			_b = temp;
		}
		_a = StringUtils.addZeroToFirst(_a, _b.length());
		// 定义返回值变量
		StringBuilder result = new StringBuilder(_a.length());
		// 循环模拟进位相加
		int sum = 0;
		int temp = 0;
		int num1 = 0;
		int num2 = 0;
		for (int i = _a.length() - 1; i >= 0; i--) {
			num1 = _a.charAt(i) - '0';
			num2 = _b.charAt(i) - '0';
			sum = num1 + num2 + temp;
			result.append(sum % 10);
			temp = sum / 10;
		}
		// 反转字符串
		result.reverse();
		// 判断最高位相加的和
		if (temp != 0)
			result.insert(0, temp);
		return result.toString();
	}