Convert String to int array in java

Question

I have one string   String arr    1 2      ie   1 2   is like a single string  How do convert this arr to int array in java

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Using Java 8 s stream library  we can make this a one-liner  albeit a long line    String str     1  2  3  4  5  6  7  8  9  0    int   arr   Arrays stream str substring 1  str length  -1  split            map String  trim  mapToInt Integer  parseInt  toArray    System out println Arrays toString arr      substring removes the brackets  split separates the array elements  trim removes any whitespace around the number  parseInt parses each number  and we dump the result in an array   I ve included trim to make this the inverse of Arrays toString int     but this will also parse strings without whitespace  as in the question   If you only needed to parse strings from Arrays toString  you could omit trim and use split        note the space

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String arr    1 2    List lt Integer gt  arrList  JSON parseArray arr Integer class  stream   collect Collectors toList     Integer   intArr   ArrayUtils toObject arrList stream   mapToInt Integer  intValue  toArray

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In tight loops or on mobile devices it s not a good idea to generate lots of garbage through short-lived String objects  especially when parsing long arrays   The method in my answer parses data without generating garbage  but it does not deal with invalid data gracefully and cannot parse negative numbers  If your data comes from untrusted source  you should be doing some additional validation or use one of the alternatives provided in other answers   public static void readToArray String line  int   resultArray        int index   0      int number   0       for  int i   0  n   line length    i  lt  n  i              char c   line charAt i           if  c                       resultArray index    number              index                number   0                    else if  Character isDigit c                 int digit   Character getNumericValue c               number   number   10   digit                       if  index  lt  resultArray length            resultArray index    number           public static int   toArray String line        int   result   new int countOccurrences line         1       readToArray line  result       return result     public static int countOccurrences String haystack  char needle        int count   0      for  int i 0  i  lt  haystack length    i              if  haystack charAt i     needle                count                        return count      countOccurrences implementation was shamelessly stolen from John Skeet

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try this one  it might be helpful for you  String arr    1 2    int   arr Stream of str replaceAll                     split      mapToInt Integer  parseInt  toArray

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final String   strings     1    2        final int   ints   new int strings length       for  int i 0  i  lt  strings length  i              ints i    Integer parseInt strings i

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String str    1 2 3 4 5 6 7 8 9 0       String items     str split           int ent     new int items length       for i 0 i lt items length i             try              ent i    Integer parseInt items i                System out println     i      ent i     Para probar          catch NumberFormatException e                 Error

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It looks like JSON - it might be overkill  depending on the situation  but you could consider using a JSON library  e g  http   json org java   to parse it       String arr     1 2         JSONArray jsonArray    JSONArray  new JSONObject new JSONTokener   data   arr       get  data         int   outArr   new int jsonArray length           for int i 0  i lt jsonArray length    i              outArr i    jsonArray getInt i

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String arr     1 2    String   items   arr replaceAll            replaceAll            replaceAll    s       split        int   results   new int items length    for  int i   0  i  lt  items length  i          try           results i    Integer parseInt items i          catch  NumberFormatException nfe              NOTE  write something here if you need to recover from formatting errors

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If you prefer an Integer   instead array of an int   array   Integer    String str     1 2    String plainStr   str substring 1  str length  -1      clear braces    String   parts   plainStr split        Integer   result   Stream of parts  mapToInt Integer  parseInt  boxed   toArray Integer    new     int    String str     1 2    String plainStr   str substring 1  str length  -1      clear braces    String   parts   plainStr split        int   result   Stream of parts  mapToInt Integer  parseInt  toArray     This works for Java 8 and higher

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Saul s answer can be better implemented splitting the string like this   string   string replaceAll     p Z   s          String   array   string substring 1  string length   - 1  split

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You can do it easily by using StringTokenizer class defined in java util package   void main             int i 0      int n   new int 2    for integer array of numbers     String st   1 2        StringTokenizer stk new StringTokenizer st                 is the delimeter     String s   new String 2    for String array of numbers      while stk hasMoreTokens                   s i  stk nextToken            n i  Integer parseInt s i     Converting into Integer        i             for i 0 i lt 2 i      System out println  number   i      n i        Output  -number 0  1           number 1  2

[java] Convert String to int array in java

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