java – Hashtable的值不会增加

public class TestCSVDataToMap {

    public static Hashtable<String,Integer> testTable = new Hashtable<>();

    public static void main (String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new FileReader("test.csv"));
        String line;
        while ((line = reader.readLine()) != null) {
            String symbol = "0";
            if(testTable.contains(symbol)) {
                int value = testTable.get(symbol);
                value++;
                testTable.put(symbol,value);
            }
            else {
                System.out.println("dash!");
                testTable.put(symbol,1);
            }
        }
        System.out.println(testTable);
    }
}

有输出：

dash!
dash!
dash!
dash!
{0=1}

为什么在解析.csv文件时密钥’0’的值没有增长？在testTable(Hashtable)中,它用(0,1)初始化,并且值应该保持增长,因为符号总是被检测为’0’的键.