1)

import java.util.*;

public class SetsUnion{
public static void main(String[] args){
Set a = new HashSet();
a.add(10);
a.add(20);
a.add(30);
a.add(40);

Set b = new HashSet();
b.add(15);
b.add(25);
b.add(35);

Set s=new HashSet(a);
s.addAll(b);
ArrayList l=new ArrayList(s);
System.out.println("Set A: "+a);
System.out.println("Set B: "+b);
System.out.println();
Collections.sort(l);
System.out.println("A U B is: "+l);
}
}

2)

import java.util.*;
class  ReverseWords{
    public static void main(String[] args)  {
        Scanner input=new Scanner(System.in);
        System.out.print("Enter String: ");
        String st=input.nextLine();
        StringBuffer buffer=new StringBuffer();
        String str[]=st.split(" ");
        for(int i=str.length-1;i>=0;i--){
        buffer.append(str[i]);
        buffer.append(" ");
        }
        System.out.println(buffer.toString());
    }
}