Reversing a String by Word or by Character

You wish to reverse a string, a character, or a word at a time. You can reverse a string by character easily, using a StringBuilder. One natural way is to use a StringTokenizer and a stack. Stack is a class that implements an easy-to-use last-in, first-out (LIFO)

import java.util.Stack;
import java.util.StringTokenizer;

public class reverse {

    public static void main(String[] argv) {
        //Using StringBuilder reverse() 
        String sh = "Hello World 2020";
        System.out.println(sh + " -> " + new StringBuilder(sh).reverse());
        //Hello World 2020 -> 0202 dlroW olleH

        //Using Stack & StringTokenizer pushing and poping whole word
        String s = "Hello World 2020";

        Stack<String> myStack = new Stack<>();
        StringTokenizer st = new StringTokenizer(s);
        while (st.hasMoreTokens()) {
            myStack.push(st.nextToken());
        }

        // Print the stack backwards
        System.out.print('"' + s + '"' + " backwards by word is:\n\t\"");
        while (!myStack.empty()) {
            System.out.print(myStack.pop());
            System.out.print(' ');
        }
        System.out.println('"');
        //"Hello World 2020" backwards by word is:
 //"2020 World Hello "
    }
}

Converting Between Unicode Characters and Strings

Unicode is an international standard that aims to represent all known characters used by people in their various languages

public class UnicodeChars {

    public static void main(String[] argv) {

        StringBuffer b = new StringBuffer();
        for (char c = 'a'; c < 'd'; c++) {
            b.append(c);
        }
        b.append('\u00a5');// Japanese Yen symbol
        b.append('\u01FC');// Roman AE with acute accent
        b.append('\u0391');// GREEK Capital Alpha
        b.append('\u03A9');// GREEK Capital Omega
        b.append('\u00E1');// á

        for (int i = 0; i < b.length(); i++) {
            System.out.printf(
                    "Character #%d (%04x) is %c%n",
                    i, (int) b.charAt(i), b.charAt(i));
        }
        System.out.println("Accumulated characters are " + b);
    }
}
//Character #0 (0061) is a
//Character #1 (0062) is b
//Character #2 (0063) is c
//Character #3 (00a5) is ¥
//Character #4 (01fc) is Ǽ
//Character #5 (0391) is Α
//Character #6 (03a9) is Ω
//Character #7 (00e1) is á
//Accumulated characters are abc¥ǼΑΩá

Java Strings Part 3
Java Strings Part 2
Java Strings Part 1