Remove Null Value from String array in java

Question

How to remove null value from String array in java   String   firstArray     test1      test2   test4         I need the  firstArray  without null   empty  values like this  String   firstArray     test1   test2   test4

User · Answer

Quite similar approve as already posted above  However it s easier to read         Remove all empty spaces from array a string array     param arr array     return array without  quot  quot      public static String   removeAllEmpty String   arr        if  arr    null          return arr       String   result   new String arr length       int amountOfValidStrings   0       for  int i   0  i  lt  arr length  i              if   arr i  equals  quot  quot                result amountOfValidStrings      arr i              result   Arrays copyOf result  amountOfValidStrings        return result

User · Answer

If you want to avoid fencepost errors and avoid moving and deleting items in an array  here is a somewhat verbose solution that uses List   import java util ArrayList  import java util List   public class RemoveNullValue     public static void main  String args           String   firstArray     test1        test2    test4       null        List lt String gt  list   new ArrayList lt String gt          for String s   firstArray           if s    null  amp  amp  s length    gt  0              list add s                       firstArray   list toArray new String list size              Added null to show the difference between an empty String instance      and null   Since this answer is around 4 5 years old  I m adding a Java 8 example   import java util Arrays  import java util stream Collectors   public class RemoveNullValue       public static void main  String args               String   firstArray     test1        test2    test4       null            firstArray   Arrays stream firstArray                        filter s - gt   s    null  amp  amp  s length    gt  0                         toArray String    new

User · Answer

This is the code that I use to remove null values from an array which does not use array lists   String   array     abc    def   null   g   null      Your array String   refinedArray   new String array length      A temporary placeholder array int count   -1  for String s   array        if s    null       Skips over null values  Add        equals s   if you want to exclude empty strings         refinedArray   count    s     Increments count and sets a value in the refined array             Returns an array with the same data but refits it to a new length array   Arrays copyOf refinedArray  count   1

User · Answer

Using Google s guava library  String   firstArray     test1      test2   test4     null    Iterable lt String gt  st Iterables filter Arrays asList firstArray  new Predicate lt String gt           Override     public boolean apply String arg0            if arg0  null    avoid null strings              return false          if arg0 length    0    avoid empty strings              return false          return true     else true

User · Answer

It seems no one has mentioned about using nonNull method which also can be used with streams in Java 8 to remove null  but not empty  as   String   origArray     Apple        Cat    Dog       null   String   cleanedArray   Arrays stream firstArray  filter Objects  nonNull  toArray String    new   System out println Arrays toString origArray    System out println Arrays toString cleanedArray      And the output is       Apple    Cat  Dog    null        Apple    Cat  Dog      If we want to incorporate empty also then we can define a utility method  in class Utils say     public static boolean isEmpty String string            return  string    null  amp  amp  string isEmpty             And then use it to filter the items as   Arrays stream firstArray  filter Utils  isEmpty  toArray String    new     I believe Apache common also provides a utility method StringUtils isNotEmpty which can also be used

User · Answer

If you actually want to add remove items from an array  may I suggest a List instead   String   firstArray     test1      test2   test4       ArrayList lt String gt  list   new ArrayList lt String gt     for  String s   firstArray      if   s equals              list add s     Then  if you really need to put that back into an array   firstArray   list toArray new String list size

User · Answer

A gc-friendly piece of code   public static lt X gt  X   arrayOfNotNull X   array        for  int p 0  N array length  p lt N    p            if  array p     null                int m p  for  int i p 1  i lt N    i  if  array i   null    m              X   res   Arrays copyOf array  m               for  int i p 1  i lt N    i  if  array i   null  res p      array i               return res                      return array      It returns the original array if it contains no nulls  It does not modify the original array

User · Answer

Those are zero-length strings  not null  But if you want to remove them   firstArray 0  refers to the first element firstArray 1  refers to the second element   You can move the second into the first thusly   firstArray 0     firstArray 1    If you were to do this for elements  1 2   then  2 3   etc  you would eventually shift the entire contents of the array to the left  eliminating element 0  Can you see how that would apply

[java] Remove Null Value from String array in java

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