找出给定字符串中第一个重复的字符串

方法一：

public class DiYiChongFu {public static void main(String[] args) {String s="abacghfgbba";System.out.println(getChar(s));}public  static char getChar(String s){int[] Ans = new int[128];for (int i = 0; i < s.length(); i++) {if (Ans[s.charAt(i)] == 0) {Ans[s.charAt(i)] = 1;}else {return s.charAt(i);}}return '无';}}

方法二：

import java.util.HashMap;public class DiYiChongFu {public static void main(String[] args) {String s="abcghfgbba";System.out.println(getFirstRepeat(s));}public static char getFirstRepeat(String s){char c=0;HashMap<Character, Integer> map=new HashMap<>();for(int i=0;i<s.length();i++){c=s.charAt(i);if(map.containsKey(c)){return  c;}else {map.put(s.charAt(i), 1);}}return c;}}