Getting rid of null in array. Java

Question

I'm not quite sure, where the problem is. Code is working properly but, after I type few words i.e:

Cat

Cats

End

It shows me:

Cat

Cats

null.

My guessing is on String k or with size of array. So I think, I need to input somehow "end" work, am i right ?

public static void main(String[] args) {
  Scanner sc = new Scanner(System. in );


  String type;
  String word;
  String words[] = new String[100];
  int i = 1;

  String k = "end";
  System.out.println("Type a word: ");
  word = sc.next();


  while (word.compareToIgnoreCase(k) != 0) {

    words[i] = word;
    i = i + 1;
    word = sc.next();
  }

  System.out.println("What type A,B,C:");
  typ = sc.next();

  if (typ.equals("B")) {
    int lenght = words.length;
    lenght = i + 1;
    i = 1;
    while (i < lenght) {
      System.out.print(words[i]);
      System.out.println();

      i = i + 1;
    }
  }
}
}

Of course, there are two more options to format text A and C. But i want to focus on that "null" thing now. — Fokuz
– Fokuz, Commented Jan 13, 2013 at 23:27
A suggestion: Try to cleanup code before posting int lenght = words.lenght; does nothing (lenght is overwritten at the very next line). And the correct spelling is length (although this is not related to programming) — SJuan76
– SJuan76, Commented Jan 13, 2013 at 23:39

StriplingWarrior · Accepted Answer · 2013-01-13 23:33:23Z

2

You just need to add that last word to the array:

while (word.compareToIgnoreCase(k) != 0) {

  words[i] = word;
  i = i + 1;
  word = sc.next();
}
words[i] = word; // Add the last item entered

By the way, I'd advise using a List<String> instead of a String[], and calling words.add(word). For one thing, this means you won't have to keep track of your index (i). More importantly, the list can get as long as you like, and you will only use as much memory as you need.

answered Jan 13, 2013 at 23:33

StriplingWarrior

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Comments

paulsm4 · Accepted Answer · 2013-01-13 23:34:21Z

0

Arrays start at "0", not "1".

// Better
int i = 0
...
while (word.compareToIgnoreCase(k) != 0) {
    words[i++] = word;
    word = sc.next();
}

i = 0;
while (i < length) {
  System.out.print(words[i++]);
  System.out.println();
}

There are several things about your logic I don't understand, but I assume you probably want to add one "word" each time.

And I'm almost certain you probably want to start at index "0", and stop at "length-1". Because "array[length]" and all subsequent elements will default to "null".

answered Jan 13, 2013 at 23:34

paulsm4

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Comments

Scott Neville · Accepted Answer · 2013-01-13 23:36:22Z

0

Your problem is that in the first loop where your adding things to the array you increment the counter after you do the assignment. This means that your index at the end represents the length + 1.

So you start at 1 (though Java arrays start at 0, so you never assign a value to the first entry in the array, not sure if thats intentional).

So when you add Cat the index becomes 2.

Further down you then add 1 to the length, with

lenght = i + 1;

The most simplest answer would be to remove this one line, though there is a lot of other re-factoring you could do to reduce the amount of code in this.

answered Jan 13, 2013 at 23:36

Scott Neville

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Comments

Raghavan · Accepted Answer · 2013-01-13 23:54:10Z

0

String type;
  String word;
  String words[] = new String[100];
  int i = 0;

  String k = "end";
  System.out.println("Type a word: ");
  word = sc.next();
words[i] = word;

  while (word.compareToIgnoreCase(k) != 0) {    
    i = i + 1;
    word = sc.next();
    words[i] = word;
  }

  System.out.println("What type A,B,C:");
  typ = sc.next();

  if (typ.equals("B")) {
    int lenght = words.length;
    i = 0;
    while (i < lenght-1) {
      System.out.print(words[i]);
      System.out.println();

      i = i + 1;
    }
  }
}

}

answered Jan 13, 2013 at 23:54

Raghavan

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