char - > String
char c = 'c';
String cc = ""+c;
String->char 这里一般是转成char[] 如果你就一个可以用
char c = StringName.charAt(0);
char[] carray = StringName.toCharArray();
String str=“abcdef”;
char[] ch=st.toCharArray();
char c = 'a';
String str = String.valueOf(c);