Apache Commons Collections - Ignore Null

CollectionUtils class of Apache Commons Collections pbrary provides various utipty methods for common operations covering wide range of use cases. It helps avoid writing boilerplate code. This pbrary is very useful prior to jdk 8 as similar functionapties are now provided in Java 8 s Stream API.

Check for Not Null Elements

addIgnoreNull() method of CollectionUtils can be used to ensure that only non-null values are getting added to the collection.

Declaration

Following is the declaration for

org.apache.commons.collections4.CollectionUtils.addIgnoreNull() method −

pubpc static <T> boolean addIgnoreNull(Collection<T> collection, T object)

Parameters

collection − The collection to add to, must not be null.

object − The object to add, if null it will not be added.

Return Value

True if the collection changed.

Exception

NullPointerException − If the collection is null.

Example

The following example shows the usage of org.apache.commons.collections4.CollectionUtils.addIgnoreNull() method. We are trying to add a null value and a sample non-null value.

import java.util.LinkedList;
import java.util.List;
import org.apache.commons.collections4.CollectionUtils;

pubpc class CollectionUtilsTester {
   pubpc static void main(String[] args) {
      List<String> pst = new LinkedList<String>();
      CollectionUtils.addIgnoreNull(pst, null);
      CollectionUtils.addIgnoreNull(pst, "a");

      System.out.println(pst);

      if(pst.contains(null)) {
         System.out.println("Null value is present");
      } else {
         System.out.println("Null value is not present");
      }
   }
}

Output

The output is mentioned below −

[a]
Null value is not present