共同学习Java源代码-数据结构-HashSet（二）

    private void writeObject(java.io.ObjectOutputStream s)
        throws java.io.IOException {
        // Write out any hidden serialization magic
        s.defaultWriteObject();


        // Write out HashMap capacity and load factor
        s.writeInt(map.capacity());
        s.writeFloat(map.loadFactor());


        // Write out size
        s.writeInt(map.size());


        // Write out all elements in the proper order.
        for (E e : map.keySet())
            s.writeObject(e);

    }

这个方法是序列化输出方法，就是调用参数输出流的方法依次输出默认对象，输出底层map的容量，输出底层map的载荷，输出底层map的大小，输出每个元素。

    private void readObject(java.io.ObjectInputStream s)
        throws java.io.IOException, ClassNotFoundException {
        // Read in any hidden serialization magic
        s.defaultReadObject();


        // Read capacity and verify non-negative.
        int capacity = s.readInt();
        if (capacity < 0) {
            throw new InvalidObjectException("Illegal capacity: " +
                                             capacity);
        }


        // Read load factor and verify positive and non NaN.
        float loadFactor = s.readFloat();
        if (loadFactor <= 0 || Float.isNaN(loadFactor)) {
            throw new InvalidObjectException("Illegal load factor: " +
                                             loadFactor);
        }


        // Read size and verify non-negative.
        int size = s.readInt();
        if (size < 0) {
            throw new InvalidObjectException("Illegal size: " +
                                             size);
        }


        // Set the capacity according to the size and load factor ensuring that
        // the HashMap is at least 25% full but clamping to maximum capacity.
        capacity = (int) Math.min(size * Math.min(1 / loadFactor, 4.0f),
                HashMap.MAXIMUM_CAPACITY);


        // Create backing HashMap
        map = (((HashSet<?>)this) instanceof LinkedHashSet ?
               new LinkedHashMap<E,Object>(capacity, loadFactor) :
               new HashMap<E,Object>(capacity, loadFactor));


        // Read in all elements in the proper order.
        for (int i=0; i<size; i++) {
            @SuppressWarnings("unchecked")
                E e = (E) s.readObject();
            map.put(e, PRESENT);
        }
    }

这个是序列化输入的方法，步骤其实和上面类似，就是生成底层map的时候会判断是否是linkedhashmap还是hashmap。