I have two problem

Question 1
ItemStack, how do I change, fill in the ID for the item, not the name of the item?
For example, STONE, I want to write 1:0

Question 2
How can I write to change this item in config.yml for material
The following is my error code

Code (Text):

ItemStack item1 = new ItemStack(Material.(Config.getString("Items1"));

Thank you for taking the time to solve my problem

 

I knew I could do this

Code (Text):

ItemStack item1 = new ItemStack(1);

The second question, how can I modify this value in the configuration file

 

Thanks