HashMap<String, String>map = new HashMap<String, String>()
map.put("name", "test")
map.put("age", "20")
看完这段代码，很多人都会觉得这么写太啰嗦了，文艺青年一般这么来了：
HashMap<String, String>map = new HashMap<String, String>() {
{
map.put("name", "test")
map.put("age", "20")
}
}
Portlet portlet = new Portlet() //Portlet 你的TestLzpJSONObject jsonObject = JSONObject.fromObject(portlet) // net.sf.json.JSONObject
Map map = new HashMap()
for (Object objectKey : jsonObject.keySet()){
String value = String.valueOf(jsonObject.get(objectKey))
map.put(objectKey,value)
}
System.out.println(map.toString())
这个问题可以跟踪一下HashMap的源码就知道了，根据输入的初始化容量（门槛？）的值（先了解HashMap中容量和负载因子的概念，其实这个和HashMap确定存储地址的算法有关），先判断是否大于最大容量，最大容量2的30次方，1<<30 =（1073741824），如果大于此数，初始化容量赋值为1<<30，如果小于此数，调用tableSizeFor方法 使用位运算将初始化容量修改为2的次方数，都是向大的方向运算，比如输入13，小于2的4次方，那面计算出来桶的初始容量就是16.
public HashMap(int initialCapacity) {this(initialCapacity, DEFAULT_LOAD_FACTOR)
}
/**
* Constructs an empty <tt>HashMap</tt> with the specified initial
* capacity and load factor.
*
* @param initialCapacity the initial capacity
* @param loadFactor the load factor
* @throws IllegalArgumentException if the initial capacity is negative
* or the load factor is nonpositive
*/
public HashMap(int initialCapacity, float loadFactor) {
if (initialCapacity < 0)
throw new IllegalArgumentException("Illegal initial capacity: " +
initialCapacity)
if (initialCapacity > MAXIMUM_CAPACITY)
initialCapacity = MAXIMUM_CAPACITY
if (loadFactor <= 0 || Float.isNaN(loadFactor))
throw new IllegalArgumentException("Illegal load factor: " +
loadFactor)
this.loadFactor = loadFactor
this.threshold = tableSizeFor(initialCapacity)
}
/**
* Returns a power of two size for the given target capacity.
*/
static final int tableSizeFor(int cap) {
int n = cap - 1
n |= n >>>1
n |= n >>>2
n |= n >>>4
n |= n >>>8
n |= n >>>16
return (n <0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1
}
