package com.test.zhipengs;/*** A Question* 给定一个字符串str，将str中连续两个字符为a的字符替换为b * 如：*  a 不替换*  b 不替换 *  ab 不替换*  ba 不替换*  aba 不替换 *  aab 替换为 bbb *  baa 替换为 bbb *  abaabaaabaa 替换为 abbbbaaabbb 中间三个a不作替换* * @author zhipengs* */
public class ReplaceTest {/*** main方法* @param args*/public static void main(String[] args) {// 测试替换方法String str1 = "aachaadaaacaaaaaaaefgaa";System.out.println("-------------------------------");System.out.println("替换前：" + str1);System.out.println("替换后：" + replace(str1));String str2 = "aaachaadaaacaaaaaaaefgaaa";System.out.println("-------------------------------");System.out.println("替换前：" + str2);System.out.println("替换后：" + replace(str2));String str3 = "ajaayaaakaac";System.out.println("-------------------------------");System.out.println("替换前：" + str3);System.out.println("替换后：" + replace(str3));String str4 = "a";System.out.println("-------------------------------");System.out.println("替换前：" + str4);System.out.println("替换后：" + replace(str4));String str5 = "b";System.out.println("-------------------------------");System.out.println("替换前：" + str5);System.out.println("替换后：" + replace(str5));String str6 = "ab";System.out.println("-------------------------------");System.out.println("替换前：" + str6);System.out.println("替换后：" + replace(str6));String str7 = "ba";System.out.println("-------------------------------");System.out.println("替换前：" + str7);System.out.println("替换后：" + replace(str7));String str8 = "aa";System.out.println("-------------------------------");System.out.println("替换前：" + str8);System.out.println("替换后：" + replace(str8));String str9 = "aaa";System.out.println("-------------------------------");System.out.println("替换前：" + str9);System.out.println("替换后：" + replace(str9));String str10 = "kjgnknk";System.out.println("-------------------------------");System.out.println("替换前：" + str10);System.out.println("替换后：" + replace(str10));}/*** 具体替换方法* @param str* @return String*/private static String replace(String str) {int len = str.length();if (null == str || len <= 1) {// str为null或只有一个时直接返回return str;}char[] charArray = str.toCharArray();// 将str转为字符数组int num = 0;// 记录字符 a 的个数 for (int i = 0; i < len; i++) {if ('a' == str.charAt(i)) {num++;} else {num = 0;// 一旦第i个字符不是 a 则num值立即清零
            }if ((num == 2 && (i + 1) < len && 'a' != charArray[i + 1])|| (num == 2 && (i + 1) == len)) {// 下一个字符存在时num值为2且下一个字符不是a;遍历到字符串末尾即没有下一个字符了时num值为2即可 charArray[i - 1] = 'b';// 把当前位置和上一个位置的字符a替换为b charArray[i] = 'b';}}return new String(charArray);// 返回结果
    }}