为什么BufferedReader read()会拾取额外字符

我正在创建一种哈夫曼编码方法,该方法使用缓冲读取器读取文件,将新的字符值添加到名为“characters[128]”的数组中,如果字符已经存在于“characters[128]”中,则将1添加到该字符的频率/计数(我将其存储在charCount[128]中,与该字符的索引相同)。我将附加我的代码,但当我运行它时,它会为最后一个字符打印出一个未知的字符(),这意味着它会比应该的时间晚一次停止while循环。你知道为什么吗?我怎样才能解决这个问题?

public Playground() {
    char c;
    int size = 0;
    char[] characters = new char[128];
    int[] charCount = new int[128];
    BufferedReader br = null;
    try {   
        br = new BufferedReader(new FileReader("input.txt"));
        while ((c = (char)br.read()) != -1) {
            for (int i = 0; i <= size; ++i) {
                if (size == 0) {
                    characters[i] = c;
                    charCount[i]++;
                    size++;
                    System.out.println("Letter/Count: " + characters[i] + "/" + charCount[i]);
                    break;
                }
                if (characters[i] == c) {
                    charCount[i]++;
                    break;
                } else if (i == size) {
                    characters[i] = c;
                    charCount[i]++;
                    size++;
                    System.out.println("Letter/Count:"+characters[i]+"/" + charCount[i]);
                    break;
                }
            }
        }
        br.close();
    } catch (IOException e){
        System.out.println("IOEXCEPTION: " + e);
    }
}
public static void main(String args[]) {
    System.out.println("Main Is Working");
    Playground p = new Playground();
    System.out.println("Constructor is not");
}