Help understanding this file

Question

import BreezyGUI.*;
public class CharTest
public static void main(String args[])
char letter = 'a', digit = '4';
System.out.println(Character.isLetter(letter)); //displays true
System.out.println(Character.digit(digit,10)); //displays 4
System.out.println(Character.digit(letter,16)); //displays 10
int i = letter;
System.out.println(i); //displays 97
GBFrame.pause();
String str = "Hey Joe!";
System.out.println(str.length());
System.out.println(str.charAt(4));
System.out.println(str.indexOf('J'));
System.out.println(str.toUpperCase());
GBFrame.pause();
I am having problems understanding the first section of this file.
ie
1. System.out.println(Character.isLetter(letter)); //displays true
....this displays true because 'a' is a letter - right, so
2. System.out.println(Character.digit(digit,10)); //displays 4
....why is 4 displayed? - I don't really understand the function of (Character.digit(digit,10)
3. System.out.println(Character.digit(letter,16)); //displays 10
....same Q as 2. why is 10 displayed, and what is the function of (letter,16)?
4. int i = letter;
System.out.println(i); //displays 97
....why is 97 displayed and not 'a'?

Answer 1

1. System.out.println(Character.isLetter(letter));
//displays true
....this displays true because 'a' is a letter -
right, soRight
2. System.out.println(Character.digit(digit,10));
//displays 4
....why is 4 displayed? - I don't really understand
the function of (Character.digit(digit,10)the method is printing a char numeric value taking the value in digit as a base 10 representation.
3. System.out.println(Character.digit(letter,16));
//displays 10
....same Q as 2. why is 10 displayed, and what is the
function of (letter,16)?This prints the char value taking the value in letter as a base 16 value (hex).
1 = 1
2 = 2
etc.
a = 10
b = 11
c = 12
d = 13
e = 14
f = 15
4. int i = letter;
System.out.println(i); //displays 97
....why is 97 displayed and not 'a'?This is basically printing the ascii value of letter.
Since char is actually an unsigned numeric data type you can easily pass a char value into an int. You can set a char by assigning it a number or a char literal
You could replace the line
char letter='a' with
char letter=97