str_prbsol.java

import java.util.Scanner;


public class str_prbsol {
    public static void main(String[] args) {
        
    Scanner sr = new Scanner(System.in);

    // qns-01
    System.out.println("Enter your string:");
    String str = sr.nextLine();
    // String name = "Ragul";
    System.out.println(str.toLowerCase());

    //qns-02
    System.out.println("Enter your String:");
    String text = sr.nextLine();
    System.out.println(text.replace(" ","_"));

    // qns-03
    System.out.println("Enter your name:");
    String name = sr.nextLine();
    System.out.println("Dear,"+name+" thanks a lot");

    // qns-04
    System.out.println("Enter your string:");
    String detect = sr.nextLine();
    System.out.println(detect.indexOf("  "));
    System.out.println(detect.indexOf("   "));
    // if compiler gives -1 as ans then it means there is no double or triple space

    // qns-05
    String letter = "Dear Harry,\n\t This course id nice.\n\t\tThanks!";
    System.out.println(letter);
    



 }
}