一、构造方法

public HashMap(int initialCapacity, float loadFactor) {
    if (initialCapacity < 0)
        throw new IllegalArgumentException("Illegal initial capacity: " +
                                           initialCapacity);
                                           
      //当初始容量太大，大于了允许的最大值时，使用最大值                                     
    if (initialCapacity > MAXIMUM_CAPACITY)
        initialCapacity = MAXIMUM_CAPACITY;
        //判断加载因子必须是大于0,而且必须是数字
    if (loadFactor <= 0 || Float.isNaN(loadFactor))
        throw new IllegalArgumentException("Illegal load factor: " +
                                           loadFactor);

    this.loadFactor = loadFactor;
    threshold = initialCapacity;
    init();
}
public HashMap(int initialCapacity) {
    this(initialCapacity, DEFAUL