1、arraylist
默认大小为10
|
1
2
3
4
|
/** * default initial capacity.*/private static final int default_capacity = 10; |
最大容量为2^30 - 8
|
1
2
3
4
5
6
7
8
9
10
11
12
|
/** * the maximum size of array to allocate. * some vms reserve some header words in an array. * attempts to allocate larger arrays may result in * outofmemoryerror: requested array size exceeds vm limit */private static final int max_array_size = integer.max_value - 8;/** * a constant holding the maximum value an {@code int} can * have, 2<sup>31</sup>-1.*/public static final int max_value = 0x7fffffff; |
扩容规则为：oldcapacity*1.5
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
|
/** * increases the capacity to ensure that it can hold at least the * number of elements specified by the minimum capacity argument. * @param mincapacity the desired minimum capacity */private void grow(int mincapacity) { // overflow-conscious code int oldcapacity = elementdata.length; int newcapacity = oldcapacity + (oldcapacity >> 1); if (newcapacity - mincapacity < 0) newcapacity = mincapacity; if (newcapacity - max_array_size > 0) newcapacity = hugecapacity(mincapacity); // mincapacity is usually close to size, so this is a win: elementdata = arrays.copyof(elementdata, newcapacity);} |
2、hashmap
默认大小： 16
|
1
2
3
4
|
/** * the default initial capacity - must be a power of two.*/static final int default_initial_capacity = 1 << 4; // aka 16 |
最大容量为：2^30
|
1
2
3
4
5
6
|
/** * the maximum capacity, used if a higher value is implicitly specified * by either of the constructors with arguments. * must be a power of two <= 1<<30.*/static final int maximum_capacity = 1 << 30; |
扩容规则为：大于oldcapacity的最小的2的n次方整数
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
|
/** * adds a new entry with the specified key, value and hash code to * the specified bucket. it is the responsibility of this * method to resize the table if appropriate. * subclass overrides this to alter the behavior of put method. */void addentry(int hash, k key, v value, int bucketindex) { if ((size >= threshold) && (null != table[bucketindex])) { resize(2 * table.length); hash = (null != key) ? hash(key) : 0; bucketindex = indexfor(hash, table.length); } createentry(hash, key, value, bucketindex);} |
总结
以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作具有一定的参考学习价值，谢谢大家对服务器之家的支持。如果你想了解更多相关内容请查看下面相关链接
原文链接：https://blog.csdn.net/u012099869/article/details/50411767
