Android String.split（“”）返回额外的元素

Question

I am trying to split a word into its individual letters.

I tried both String.split("") and String.split("|") however when I split a word it is creating a extra empty element. Example:

    word = "word";
    int n = word.length();
    Log.i("20",Integer.toString(n));
    String[] letters = word.split("|");
    Log.i("25",Integer.toString(letters.length));

The output in the Android Monitor is:

07-21 15:50:23.084 5711-5711/com.strizhevskiy.movetester I/20: 4
07-21 15:50:23.085 5711-5711/com.strizhevskiy.movetester I/25: 5

I put the individual letters into TextView blocks and I can actually see an extra empty TextView.

When I test these methods in my regular Java it outputs the expected answer: 4.

I am almost tempted to think this is an actual bug in Android's implementation of the method.

Answer 1

I am thinking you want to do this:

public Character[] toCharacterArray( String s ) {

   if ( s == null ) {
       return null;
   }

   int len = s.length();
   Character[] array = new Character[len];
   for (int i = 0; i < len ; i++) {
      array[i] = new Character(s.charAt(i));
   }

   return array;
}

Instead of splitting a word without delimiters?

I hope this helps!

Answer 2

It's hard to say if it's bug or expected behavior, because what are you doing doesn't make sense. You are trying to split string with logical OR ( split is waiting for Regular expression , not just a string), so as result it could be different result in Android comparing with normal java, and I don't see there any issue.

Anyway, there is many ways to achieve what you want in a normal way, eg just iterating over word by each char in a cycle or just use toCharArray String's method.

Answer 3

Thank you for the suggestions. My current work-around is to use a mock array and copying over into a fresh array using System.arraycopy().

String[] mockLetters = word.split("");
int n = word.length();
String[] letters = new String[n];

System.arraycopy(mockLetters,1,letters,0,n);

I appreciate the suggestions to use toCharArray(). However, these letters then get put into TextViews and TextView doesnt seem to accept char. I could, of coarse, make it work but I've decided to stick with what I currently have.

Tom, in a comment to my question, answered my underlying issue: Why String.split() worked differently in Android than it does in Java?

Apparently the rules for String.split() changed with Java 8.

Answer 4

Try passing a 0 as the limit per the documentation below so that the trailing spaces are discarded.

String[] split (String regex, int limit)

If n is zero then the pattern will be applied as many times as possible, the array can have any length, and trailing empty strings will be discarded.