is it correct to compare like if(null == object) or if(object == null) in java [closed]

Question

I am working in a project there is a statement like below

if(null == object)
{
//do something
}

is it same as

if(object == null){
// do something 
}

Give some example so that both are same or different .

Answer 1

There is no difference in this specific case. Matter of style. The first style is Yoda style of coding usually write to avoid null pointer. But this case, it's the same.

The example from wiki

String myString = null;
if (myString.equals("foobar")) { /* ... */ }
// This causes a NullPointerException in Java

With Yoda conditions:

String myString = null;
if ("foobar".equals(myString)) { /* ... */ }
// This is false, as expected

Note that avoiding NullPointerException is not always an advantage. Covering them may cause other bugs or eat more time to debug your code.

Answer 2

The operator == is symmetric.

x == null is equalent to null == x. But using the first way is more readable and habitually.

There are other ways to check for null value in the object:

1. boolean Objects.nonNull(Object obj) // obj != null
2. T Objects.requireNonNull(T obj) // checks out obj and returns it if it isn't null

---

Example:

String v = "value";

System.out.println(v == null ? null : v);
System.out.println(null == v ? null : v);

Output:

value
value