How do I remove objects from an array in Java?

Question

Given an array of n Objects, let\'s say it is an array of strings, and it has the following values:

foo[0] = \"a\";
foo[1]          


        

Answer 1

If it doesn't matter the order of the elements. you can swap between the elements foo[x] and foo[0], then call foo.drop(1).

foo.drop(n) removes (n) first elements from the array.

I guess this is the simplest and resource efficient way to do.

PS: indexOf can be implemented in many ways, this is my version.

Integer indexOf(String[] arr, String value){
    for(Integer i = 0 ; i < arr.length; i++ )
        if(arr[i] == value)
            return i;         // return the index of the element
    return -1                 // otherwise -1
}

while (true) {
   Integer i;
   i = indexOf(foo,"a")
   if (i == -1) break;
   foo[i] = foo[0];           // preserve foo[0]
   foo.drop(1);
}

Answer 2

Initial array

   int[] array = {5,6,51,4,3,2};

if you want remove 51 that is index 2, use following

 for(int i = 2; i < array.length -1; i++){
    array[i] = array[i + 1];
  }

Answer 3

In an array of Strings like

String name = 'a b c d e a f b d e' // could be like String name = 'aa bb c d e aa f bb d e'

I build the following class

class clearname{
def parts
def tv
public def str = ''
String name
clearname(String name){
    this.name = name
    this.parts = this.name.split(" ")
    this.tv = this.parts.size()
}
public String cleared(){

        int i
        int k
        int j=0        
    for(i=0;i<tv;i++){
        for(k=0;k<tv;k++){
            if(this.parts[k] == this.parts[i] && k!=i){
               this.parts[k] = '';
                j++
            }
        }
    }
    def str = ''
    for(i=0;i<tv;i++){
        if(this.parts[i]!='')

           this.str += this.parts[i].trim()+' '
    } 
    return this.str    
}}



return new clearname(name).cleared()

getting this result

a b c d e f

hope this code help anyone Regards

Answer 4

You can always do:

int i, j;
for (i = j = 0; j < foo.length; ++j)
  if (!"a".equals(foo[j])) foo[i++] = foo[j];
foo = Arrays.copyOf(foo, i);

Answer 5

Something about the make a list of it then remove then back to an array strikes me as wrong. Haven't tested, but I think the following will perform better. Yes I'm probably unduly pre-optimizing.

boolean [] deleteItem = new boolean[arr.length];
int size=0;
for(int i=0;i<arr.length;i==){
   if(arr[i].equals("a")){
      deleteItem[i]=true;
   }
   else{
      deleteItem[i]=false;
      size++;
   }
}
String[] newArr=new String[size];
int index=0;
for(int i=0;i<arr.length;i++){
   if(!deleteItem[i]){
      newArr[index++]=arr[i];
   }
}

Answer 6

Assign null to the array locations.