StringBuilder capacity()

Question

I noticed that the capacity method returns StringBuilder capacity without a logic way ... sometime its value is equals to the string length other t

Answer 1

Here's the logic: If you define a new instance of the StringBuilder class without a constructor, like so new StringBuilder(); the default capacity is 16. A constructor can be either an int or a String. For a String constructor, the default capacity is calculated like this

int newCapacity = string.length() + 16;

For an int constructor, the capacity is calculated like this

int newCapacity = intSpecified + 16;

If a new String is appended to the StringBuilder and the new length of the String is greater than the current capacity, then the capacity is calculated like this:

int newCapacity = (oldCapacity + 1) * 2;