CODEWITHSUNDEEP
javastringarraylist
Kibbles
Kibbles

Reputation: 3

Why is this if statement always returning true?

Suppose: list = ["be", "be", "is", "not", "or", "question", "that", "the", "to", "to"]

public static void removeDuplicates(ArrayList<String> list) {
    for(int i = 0; i < list.size(); i++) {
        String s = list.get(i);
        for(int j = 0; j < list.size() - 1; j++) {
            String s2 = list.get(j);
            if(s2.equals(s)); {
                list.remove(j + 1);
            }
        }
    }
}

When I debug it, s2.equals(s) seems to be returning true all the time when s2 and s does not equal to each other at all. What am I doing wrong?

Upvotes: 0

Views: 95

Answers (4)

Deepak Bhatia
Deepak Bhatia

Reputation: 6276

You should start your second loop from i+1, because in every iteration for j loop the i value will be equal to j and it will satisfy the equals condition .... 

public static void removeDuplicates(ArrayList<String> list) 
{
  for(int i = 0; i < list.size(); i++) 
  {
    String s = list.get(i);
    for(int j = i+1; j < list.size(); j++) 
    {
        String s2 = list.get(j);
        if(s2.equals(s))             
        {   
           list.remove(j + 1);
           j--; //Subtract one as j+1 element is removed from list and index changes
        }

    }
  }
}

Upvotes: 1

Denys S&#233;guret
Denys S&#233;guret

Reputation: 382150

You're testing elements against themselves too and you have a semicolon effectively removing the if. You probably want

if (i!=j && s2.equals(s)) {

Upvotes: 1

Axel
Axel

Reputation: 14159

Remove the semicolon:

        if(s2.equals(s)); {

Should be 

        if(s2.equals(s)) {

EDIT: Explanantion: In your code, you have an empty statement after the if, and so the block will be executed regardless of the comparison result:

public static void removeDuplicates(ArrayList<String> list) {
    for(int i = 0; i < list.size(); i++) {
        String s = list.get(i);
        for(int j = 0; j < list.size() - 1; j++) {
            String s2 = list.get(j);
            if(s2.equals(s))
                ; // <-- conditional
            {     // <-- unconditional
                list.remove(j + 1);
            }
        }
    }
}

Upvotes: 3

Shrikant Kakani
Shrikant Kakani

Reputation: 1561

You have an extra semicolon. Do as follows:

if(s2.equals(s))             
    list.remove(j + 1);

and this change should work.

Upvotes: 1

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