Map 的初始容量是多少（hashMap）

  static final int DEFAULT_INITIAL_CAPACITY = 1 << 4; // aka 16

    /**
     * Constructs an empty <tt>HashMap</tt> with the default initial capacity
     * (16) and the default load factor (0.75).
     */
    public HashMap() {
        this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR);
    }