Null check in an enhanced for loop

Question

What is the best way to guard against null in a for loop in Java?

This seems ugly :

if (someList != null) {
    for (Object object : someList) {
            


        

Answer 1

Use ArrayUtils.nullToEmpty from the commons-lang library for Arrays

for( Object o : ArrayUtils.nullToEmpty(list) ) {
   // do whatever 
}

This functionality exists in the commons-lang library, which is included in most Java projects.

// ArrayUtils.nullToEmpty source code 
public static Object[] nullToEmpty(final Object[] array) {
    if (isEmpty(array)) {
        return EMPTY_OBJECT_ARRAY;
    }
    return array;
}

// ArrayUtils.isEmpty source code
public static boolean isEmpty(final Object[] array) {
    return array == null || array.length == 0;
}

This is the same as the answer given by @OscarRyz, but for the sake of the DRY mantra, I believe it is worth noting. See the commons-lang project page. Here is the nullToEmpty API documentation and source

Maven entry to include commons-lang in your project if it is not already.

    org.apache.commons
    commons-lang3
    3.4

Unfortunately, commons-lang doesn't provide this functionality for List types. In this case you would have to use a helper method as previously mentioned.

public static  List nullToEmpty(List list)
{
    if(list == null || list.isEmpty())
    {
        return Collections.emptyList();
    }
    return list;
}