Remove Null Value from String array in java

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 && 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.

Using Google's guava library

String[] firstArray = {"test1","","test2","test4","",null};

Iterable<String> st=Iterables.filter(Arrays.asList(firstArray),new Predicate<String>() {
    @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
    }
});

If you actually want to add/remove items from an array, may I suggest a List instead?

String[] firstArray = {"test1","","test2","test4",""};
ArrayList<String> list = new ArrayList<String>();
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()]);

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<String> list = new ArrayList<String>();

    for(String s : firstArray) {
       if(s != null && s.length() > 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 -> (s != null && s.length() > 0))
                     .toArray(String[]::new);    

    }
}