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I'm trying to convert a string filled with 16 digits into an array of ints where each index holds the digit of its respective index in the string. I'm writing a program where I need to do math on individual ints in the string, but all of the methods I've tried don't seem to work. I can't split by a character, either, because the user is inputting the number.

Here's what I have tried.

//Directly converting from char to int 
//(returns different values like 49 instead of 1?)    
//I also tried converting to an array of char, which worked, 
//but then when I converted
//the array of char to an array of ints, it still gave me weird numbers.

for (int count = 0; count <=15; count++)
{
   intArray[count] = UserInput.charAt(count);
}

//Converting the string to an int and then using division to grab each digit,
//but it throws the following error (perhaps it's too long?):
// "java.lang.NumberFormatException: For input string: "1234567890123456""

int varX = Integer.parseInt(UserInput);
int varY = 1;
for (count=0; count<=15; count++)
{
    intArray[count]= (varX / varY * 10);
}

Any idea what I should do?

share|improve this question
1  
Yes, that number (1234567890123456) is too big for an int, which has a max value of (2^32-1) – Keyser May 13 '12 at 11:33
Delete the question if you think it should be, don't edit it with a thousand x'es... Other users might find useful information in the original question, even if it is stupid. – Hidde May 14 '12 at 19:40

2 Answers

up vote 3 down vote

how about this:

for (int count = 0; count < userInput.length; ++count)
   intArray[count] = userInput.charAt(count)-'0';
share|improve this answer
That worked perfectly! Thank you so much :) Can I ask what the changes did? I noticed you changed it to ++count and added - '0' to the end. – user1392072 May 13 '12 at 11:56
1  
the "++" is a super tiny performance tip that came from the C++ days , i think java compiler is good enough to recognize it can optimize it too . the '0' makes it easier to understand how to convert from a char to a number , since '0'-'0' ==0 , '1'-'0'==1 , and so on ... – android developer May 13 '12 at 12:18
up vote 0 down vote

I think that the thing that is a bit confusing here is that ints and chars can be interpited as eachother. The int value for the character '1' is actually 49.

Here is a solution:

for (int i = 0; i < 16; i++) {
    intArray[i] = Integer.valueOf(userInput.substring(i, i + 1));
}

The substring method returns a part of the string as another string, not a character, and this can be parsed to an int.

Some tips:

  • I changed <= 15 to < 16. This is the convetion and will tell you how many loop interations you will actually go throug (16)
  • I changed "count" to "i". Another convention...
share|improve this answer
Thanks for that explanation :) I am very bad with conventions ;( I appreciate the suggestions and I will try to be more conventional from now on! – user1392072 May 13 '12 at 12:06

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