Converting a String into a array.

[taraxgoesxboom]

Hi,

I'm working on a program right now where I need to convert a String into an array. I thought I got it working, but I keep having runtime errors.

This is the coding I have so far:

String phrase;

phrase = keyboard.next();

String[] userPhrase = new String[80];


userPhrase = phrase.split("");



If the "user" enters something without spaces (for ex. ABA) it works fine, but if it has spaces I keep getting errors.

I'm assuming I don't have the correct parameters when calling the split method? But I'm having a hard time figuring out what I need to put in place of the quotation marks. If someone could point me in the right direction I would appreciate it.

[Steve11235]

First, don't create an array when you define userPhrase. That array gets thrown away immediately. Use "null" instead.

The expression used in split("") must be a regular expression. If you want to split on blanks, use " +".

Here's a good regular expression site.

[taraxgoesxboom]

I'm still a little confused. I realized what I was trying to do wouldn't even make logical sense if it had worked.

Let me explain what I'm trying to do better. We're working on a palindrome program that checks to see if a word if the same frontwards as backwards. But, it's required we use at least one array to check. What I need to do is take a string the user enters and turn it into an array of characters (that includes spaces as characters as well.)

Am I even on the right track with the string method or is there something else I should be looking into?

-Thanks.

[Steve11235]

First, use String.toCharArray().

Second, think about how you would practically define a palindrome. Using only plain English words, describe the steps you would follow to manually test an entry. Turn those steps into code.

Here's a thought about an "elegant" solution. An array can be accessed from both ends by using two indexes.

[CJSLMAN]

... and adding to the above what Steve said, it can all be done with one "while" loop !!!

Luck,
CJSL

[Steve11235]

We should have a Java Challenge to see who can cram all the code into a single "for" statement while using as few letters as possible. Or is that a C Challenge? ;-)

[emceenugget]

it can be done in java, but i always imagine c being used for the impractical challenges.

[CJSLMAN]

yeah... sounds fun ... did it with "for" loop, two variables and 4 lines of code (made it as a method).

CJSL

[angryboy]

ah ha! i've done it in 108 characters. not very readable though...

// "as few letters as possible."
public boolean p(char[] c){
for([B]/*...*/[/B])if([B]/*...*/[/B])return false;
return true;
}

[emceenugget]

after trying it out, if this were c, you would be able to cut more corners, since booleans are just ints. and it would be a lot easier to do in c if you actually require something that'll compile

[angryboy]

less effective, but i wrote a palindrome method using StringBuffer.reverse() and String.compareTo(). max is 93 chars and no for loop.

[Steve11235]

I like the StringBuffer solution a lot better...

[angryboy]

Its better in readibility, but not performance. I ran it on a list of palindromes for 100,000 loops.

String[] sArray = {"aibohphobia","alula","cammac","civic","deified","deleveled","detartrated","devoved","dewed","evitative","Hannah","kayak","kinnikinnik","lemel","level","madam","Malayalam","minim","murdrum","peeweep","racecar","radar","redder","refer","reifier","repaper","reviver","rotator","rotavator","rotor","sagas","solos","sexes","stats","tenet","terret","testset" };

//String.toCharArray() solution
Time:   1.181 secs

//StringBuffer.reverse() solution
Time:   4.366 secs

for(int i=0; i<100000; i++)
  for(String s : sArray){
    Word.isPalindrome(s);
  }

and the timing for String.toCharArray() solution would be even less if it's a mixed list.