字符流中第一个不重复的字符 java

题目描述

如果当前字符流没有存在出现一次的字符，返回#字符。

package niuke.easy;

import java.util.ArrayList;
import java.util.HashMap;

public class FirstAppearingOnce {
HashMap<Character, Integer> map = new HashMap<Character, Integer>();// 存放字符和其出现的次数
ArrayList<Character> list = new ArrayList<Character>();// 存放字符

public static void main(String[] args) {

}

// Insert one char from stringstream
public void Insert(char ch) {
if (map.containsKey(ch)) {
map.put(ch, map.get(ch) + 1);
} else {
map.put(ch, 1);
}
list.add(ch);
}

// return the first appearence once char in current stringstream
public char FirstAppearingOnce() {
for (int i = 0; i < list.size(); i++) {
if (map.get(list.get(i)) == 1) {
return list.get(i);
}
}
return '#';
}
}