Java (while statement) basic problem that beginners did first

Output of the first Java while statement problem

Question 1

Roll two dice, how many times do you get doublet?

[Execution example]

1st (2,3) 2nd (3,2) 3rd (4,4) 3rd doublet!

[Example answer] 
import java.util.*;
public class Main{
    public static void main(String[] args){
        Random rand=new Random();
        int count=0;
        while(true){
            count++;
            int dice1=rand.nextInt(6)+1;
            int dice2=rand.nextInt(6)+1;
            System.out.printf("%dth time(%d,%d)%n",count,dice1,dice2);
            if(dice1 == dice2){
                break;
            }
        }
        System.out.println(count+"The second time I got doublet!");
    }
}

Question 2

Realize the following processing.

[Execution example]

9 8 7 6 5 4 3 2 1 firing!

[Example answer] 
import java.util.*;
public class Main{
    public static void main(String[] args){
        int n=9;
        while(n>0){
            System.out.println(n);
            n--;
        }
        System.out.println("firing!");
    }
}

Question 3

Generate random numbers from 1 to 999 repeatedly and display the number of times until 777 appears for the first time.

[Execution example]

1:34 2:432 3:321 ..... 1034: 777 1034 The 777 came out for the third time!

[Example answer] 

import java.util.*;
public class Main{
    public static void main(String[] args){
        Random rand=new Random();
        int num=-1;
        int count=0;
        while(num !=777){
            count++;
            num=rand.nextInt(999)+1;
            System.out.printf("%d:%d%n",count,num);
        }
        System.out.println(count+"I got 777 for the second time!");
    }
}

Question 4

[Execution result] Positive integer> 20 1 2 Fizz 4 Buzz Fizz 7 8 Fizz Buzz 11 Fizz 13 14 FizzBuzz 16 17 Fizz 19 Buzz

[Example answer] 

import java.util.*;
public class Main{
public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        System.out.print("Positive integer>");
        int max=sc.nextInt();
        int i=1;
        String ans;
        while(i<=max){
            if(i %3 == 0 && i % 5== 0){
                ans="FizzBuzz";
            }else if(i % 3==0){
                ans="Fizz";
            }else if(i % 5==0){
                ans="Buzz";
            }else{
                ans=i+"";
            }
            System.out.println(ans);
            i++;
        }
    }
}

It is recognition.