Empty an array in Java processing

Question

Other than looping through each element in an array and setting each one to null  is there a native function in Java   processing to simply empty an array  or destroy it  to be able to redeclare it as a new array

User · Answer

I just want to add something to Mark s comment   If you want to reuse array without additional allocation  just use it again and override existing values with new ones  It will work if you fill the array sequentially  In this case just remember the last initialized element and use array until this index  It is does not matter that there is some garbage in the end of the array

User · Answer

If Array xco is not final then a simple reassignment would work   i e   xco   new Float xco  length     This assumes you need the Array xco to remain the same size  If that s not necessary then create an empty array   xco  new Float 0

User · Answer

I was able to do that with the following 2 lines  I had an array called selected items used to get all selected items on a dataTable   selected items   null  selected items

User · Answer

There s  Arrays fill myArray  null     Not that it does anything different than you d do on your own  it just loops through every element and sets it to null    It s not native in that it s pure Java code that performs this  but it is a library function if maybe that s what you meant   This of course doesn t allow you to resize the array  to zero   if that s what you meant by   empty    Array sizes are fixed  so if you want the  new  array to have different dimensions you re best to just reassign the reference to a new array as the other answers demonstrate   Better yet  use a List type like an ArrayList which can have variable size

User · Answer

Faster clearing than Arrays fill is with this  From Fast Serialization Lib   I just use arrayCopy  is native  to clear the array   static Object   EmptyObjArray   new Object 10000    public static void clear Object   arr        final int arrlen   arr length      clear arr  arrlen      public static void clear Object   arr  int arrlen        int count   0      final int length   EmptyObjArray length      while  arrlen - count  gt  length            System arraycopy EmptyObjArray 0 arr count  length           count    length            System arraycopy EmptyObjArray 0 arr count  arrlen -count

User · Answer

Take double array as an example  if the initial input values array is not empty  the following code snippet is superior to traditional direct for-loop in time complexity   public static void resetValues double   values      int len   values length    if  len  gt  0        values 0    0 0        for  int i   1  i  lt  len  i    i        System arraycopy values  0  values  i    len - i   lt  i     len - i    i

User · Answer

array   new String array length

User · Answer

You can simply assign null to the reference   This will work for any type of array  not just ints   int   arr   new int   1  2  3  4   arr   null    This will  clear out  the array   You can also assign a new array to that reference if you like   int   arr   new int   1  2  3  4   arr   new int   6  7  8  9     If you are worried about memory leaks  don t be   The garbage collector will clean up any references left by the array   Another example   float   arr       some array that you want to clear arr   new float arr length     This will create a new float   initialized to the default value for float

[java] Empty an array in Java / processing

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