在 do while 循环中我的 if else 语句出现问题

Question

My do-while loop is supposed to print out numbers from 1 - 106 (including 1 and 106)

whats supposed to happen: multiples of 3 are supposed to print out Big, multiples of 5 are supposed to print out Mean, multiples of 7 are supposed to print out Bugs, multiples of 3 and 5 are supposed to print out BigMean, multiples of 3 and 7 are supposed to print out BigBugs, multiples of 5 and 7 are supposed to print out MeanBugs, multiples of 3, 5 and 7 are supposed to print out BigMeanBugs.

What actually happens: my do-while loop only runs the first "if" statement. Any help?

My code:

public static void main(String [] args){
      
    int i = 0;      
    do{
        ++i;
        if(i %3 == 0){
            System.out.print("Big, ");
             
            if(i %5 ==0){
                System.out.print("Mean, ");
            }
            if(i %7 ==0){
                System.out.print("Bugs, "); 
            }
            if((i %3 == 0) && (i %5 == 0)){
                System.out.print("BigMean, ");
            }
            if((i %3 == 0) && (i %7 == 0)){
                System.out.print("BigBugs, ");
            }
               
        }else if((i %5 == 0) && (i %7 == 0)){
            System.out.print("MeanBugs, ");
               
        }else if((i %3 == 0) && (i %5 == 0) && (i %7 ==0)){
            System.out.print("BigMeanBugs, ");
                     
        }else{
            System.out.print(i + " ");
        }               
    }while(i<=106);   
            
}//closing main

Answer 1

As I could see your problem is probably that your if-statements are inside of first if-statement , so maybe you want this:

public class BigMeanBugsDoWhileLoop
{
  public static void main(String [] args)
  {
  
    int i = 0;  
    
    do
    {
        ++i;
        boolean bug = false;
        String result = "";

        if(i %3 == 0)
        {
            result += "Big";
            bug = true;
        }
        
        if(i %5 ==0)
        {
            result += "Mean";
            bug = true;
        }
        
        if(i %7 ==0)
        {
            result += "Bugs";
            bug = true;
        }
        
        if(!bug)
        {
           System.out.println(i + "");
        }
        else
        {
           System.out.println(result);
        }
    }while(i<106);   
        
  }//closing main
 
} // closing class

You don't need other if-statements because you don't use break so other expressions will be evaluated before next iteration.

Answer 2

• First, if something is divisible by 3 and 7 it is divisible by 21.
• Second, if you reverse the order, you will catch divisible by 3 and 5 before divisible by 3 or 5 separately (assuming that is what you want). If you do it the other way you may print the values prematurely or miss them altogether before checking the other possible factors. This behavior is also dependent on if vs if/else if statements.

I have limited the printout to 25 to avoid a long list. Modify as you see fit.

public class BigMeanBugsDoWhileLoop {
    public static void main(String[] args) {
        int i = 1;
        do {
            String bugType = "";
            if (i % 105 == 0) {
                bugType = "BigMeanBugs";  // 3 5 7
            } else if (i % 35 == 0) {
                bugType = "MeanBugs";     // 5 7 
            } else if (i % 21 == 0) {   
                bugType = "BigBugs";      // 3 7
            } else if (i % 15 == 0) {
                bugType = "BigMean";      // 3 5
            } else if (i % 7 == 0) {       
                bugType = "Bugs";         // 7
            } else if (i % 5 == 0) {
                bugType = "Mean";         // 5
            } else if (i % 3 == 0) {
                bugType = "Big";          // 3
            }
            System.out.println(bugType.isEmpty() ? i : bugType);
            i++;
        } while (i <= 25);
        
    }// closing main
    
} // closing class

Prints this.

1
2
Big
4
Mean
Big
Bugs
8
Big
Mean
11
Big
13
Bugs
BigMean
16
17
Big
19
Mean
BigBugs
22
23
Big
Mean

Answer 3

You have to increment the value of i in the end of loop

public static void main(String [] args){
  
     int i = 1;
     
     do{   
        
        if(i %3 == 0){
          System.out.print("Big, ");
         
           if(i %5 ==0){
             System.out.print("Mean, ");
           }
              if(i %7 ==0){
                System.out.print("Bugs, "); 
              }
                 if((i %3 == 0) && (i %5 == 0)){
                   System.out.print("BigMean, ");
                 }
                    if((i %3 == 0) && (i %7 == 0)){
                      System.out.print("BigBugs, ");
                    }
           
                    }else if((i %5 == 0) && (i %7 == 0)){
                      System.out.print("MeanBugs, ");
           
                 }else if((i %3 == 0) && (i %5 == 0) && (i %7 ==0)){
                   System.out.print("BigMeanBugs, ");
                 
           }else{
             System.out.print(i + " ");
           }
           i++;
        }while(i<=106);

        
     }//closing main
 
  } // closing class