Using anonymous internal classes in Java for simple double arc Initialization

Java Collection frameworks such as set, map, and list do not provide any simple method for initialization. Each time a set is created, values must be added one by one. For example

CopyCode The Code is as follows: Set <character> letter = new hashset <character> ();
Letter. Add ('A ');
Letter. Add ('B ');
//...

Very tedious.

But use an anonymous internal class. It can be slightly simpler.

Copy code The Code is as follows: Set <character> letter = new hashset <character> ()
{
{
Add ('A'); add ('B'); add ('C'); add ('D ');
Add ('E'); add ('F'); add ('G'); add ('H ');
Add ('I'); add ('J'); add ('k'); add ('l ');
Add ('M'); add ('n'); add ('O'); add ('P ');
Add ('q'); add ('R'); add ('s'); add ('T ');
Add ('U'); add ('V'); add ('W'); add ('x ');
Add ('y'); add ('Z ');
Add ('A'); add ('B'); add ('C'); add ('D ');
Add ('E'); add ('F'); add ('G'); add ('H ');
Add ('I'); add ('J'); add ('k'); add ('l ');
Add ('M'); add ('n'); add ('O'); add ('P ');
Add ('q'); add ('R'); add ('s'); add ('T ');
Add ('U'); add ('V'); add ('W'); add ('x ');
Add ('y'); add ('Z ');
}
}; // The first layer of brackets defines the anonymous internal class, and the second layer is the initialization module.