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General Discussion

chris salvi
chris salvi
7,584 Points
Posted by chris salvi
chris salvi
7,584 Points

question on JAVA example (more of a general question on coding with nested while loops)

I understand this site doesn't have lessons on Java, but my question really pertains more to how to understand these nested while loops below. This is from straight from a textbook, so I know the code is correct, but I don't understand the placement of the increment values of the var i and j. From what I gather, the code takes two strings of arbitrary length, lets call s1=food, s2=brood, and then starts checking the values.

Am I thinking of this correctly? If so, then why does the j++ increment stay outside the nested loop? I think the program is locking into place the first character of s1 while s2 cycles through all of its characters to see if there is a potential match, but then if there is no match, the j++ goes to the 2nd character in s2. Yet I don't see why the j++ should be outside the nested loop in this case.

boolean nothingInCommon;
nothingInCommon=true;

int i,j;

 i=0;

bigloop:while (i<s1.length()){

      j=0;
      while(j<s2.length()){
              if(s1.charAt(i)==s2.charAt(j))
                 nothingInCommon=false;
                 break bigloop;  
                 }
             j++;
}
     i++;
}

2 Answers

chris salvi
chris salvi
7,584 Points
chris salvi
chris salvi
7,584 Points

also how does the j variable know to reset at the beginning of s2 once it has cycles through the initial character set and then the i++ is implemented?

John W
John W
21,558 Points
John W
John W
21,558 Points

If you matched your indentation level, i++ is indeed within the bigloop :) That's why proper indentation is so valuable.

boolean nothingInCommon;
nothingInCommon=true;

int i,j;

 i=0;

bigloop:while (i<s1.length()){

         j=0;
         while(j<s2.length()){     // <-- Beginning of inner loop
                  if(s1.charAt(i)==s2.charAt(j)) {
                           nothingInCommon=false;
                           break bigloop;  
                  }
                   j++;                            // Increment inner loop counter
         }                        // <-- End of inner loop

         i++;                                     // Increment bigloop counter
}          // <-- End of big loop