Java SE (Java Platform, Standard Edition)

I am trying to use char like I usually use doble but doesnt work

Here is using double:

lb = JOptionPane.showInputDialog("Enter the pounds: ");
    			pounds = Double.parseDouble(lb);

Here is using char:

message = JOptionPane.showInputDialog("Welcome to Converting Weight System!\n"
    					+ "Please enter P to convert your kilograms weight to Pounds "
    					+ "or K to convert your pounds weight to Kilograms: ");
    	choice = Character.parseChar(message);

Probably when you use char is different but I dont know how, can some one help me please.