Best way to check for null values in Java?

Question

Before calling a function of an object, I need to check if the object is null, to avoid throwing a NullPointerException.

What is the best way to go abou

Answer 1

You also can use StringUtils.isNoneEmpty("") for check is null or empty.

Answer 2

In Java 8, the best way to check for null is:

Objects.isNull(obj) //returns true if the object is null

Objects.nonNull(obj) //returns true if object is not-null

if(Objects.nonNull(foo) && foo.something()) // Uses short-circuit as well. No Null-pointer Exceptions are thrown.

Apart from this... You can also go with Guava's Optional Class

Answer 3

Method 4 is best.

if(foo != null && foo.bar()) {
   someStuff();
}

will use short-circuit evaluation, meaning it ends if the first condition of a logical AND is false.

Answer 4

In Java 7, you can use Objects.requireNonNull(). Add an import of Objects class from java.util.

public class FooClass {
    //...
    public void acceptFoo(Foo obj) {
        //If obj is null, NPE is thrown
        Objects.requireNonNull(obj).bar(); //or better requireNonNull(obj, "obj is null");
    }
    //...
}

Answer 5

if you do not have an access to the commons apache library, the following probably will work ok

if(null != foo && foo.bar()) {
//do something
}

Answer 6

Method 4 is far and away the best as it clearly indicates what will happen and uses the minimum of code.

Method 3 is just wrong on every level. You know the item may be null so it's not an exceptional situation it's something you should check for.

Method 2 is just making it more complicated than it needs to be.

Method 1 is just method 4 with an extra line of code.