Java: How to Check If Object Is Null

How to check if object is null or not except == null

The easiest way to check is entity == null. There is no shorter way to do that.

Note that there is a method for this in the standard lib:

Objects.isNull(Object obj)

And another one which is the opposite of the above one:

Objects.nonNull(Object obj)

And there is yet another one which can be used to force a value to be not null, it throws a NullPointerException otherwise:

T Objects.requireNonNull(T obj);

Note: The Objects class was added in Java 7, but the isNull() and nonNull() methods were added only in Java 8.

Java: How to check if object is null?

Edited Java 8 Solution:

final Drawable drawable = 
    Optional.ofNullable(Common.getDrawableFromUrl(this, product.getMapPath()))
        .orElseGet(() -> getRandomDrawable());

You can declare drawable final in this case.

As Chasmo pointed out, Android doesn't support Java 8 at the moment. So this solution is only possible in other contexts.

How check if an Attribute(object) is null in Java

You code breaks Demeter's law. That's why it's better to refactor the design itself.
As a workaround, you can use Optional

   var = Optional.ofNullable(object1)
    .map(o -> o.getIdObject11())
    .map(o -> o.getIdObject111())
    .map(o -> o.getDescription())
    .orElse("")

shorter way to check if an object is null?

No.

Java requires the expression of a conditional statement has to be of type boolean, or something automatically convertible to a boolean; the only type which can be so converted is Boolean, via unboxing.

Unless you define a method with a meaninglessly short name, you can't do this with fewer characters:

if (n(str)) {   // "n()" requires 3 characters
if (str == null) {  // " == null" requires 8 characters
                    // (remove the whitespace if you want to do it in 6...)

But those 5 extra characters save an awful lot of cognitive burden, of wondering "what on earth is n?!", not to mention the additional characters of defining and/or importing that method. On the other hand, anybody who has written any Java (or, likely, some other language) instantly understands == null.

str == null precisely conveys what you're testing for: that the reference is null, as opposed to empty, or convertible to a number whose value is zero, or something else.

== null also has beneficial compile-time properties, for example that it will stop you using a primitive operand, for example int i = 0; if (i == null) {} is a compile-time error, because i is primitive and thus cannot be null, whereas if (n(i)) {} would be allowed (provided the formal parameter type is Object, which you'd want it to be, for maximum reuse), because i would be boxed.

Java is a reasonably verbose language; there are many things that are more verbose than this. Personally, I wouldn't even notice writing == null, it is that conditioned into my muscle memory.

Stop worrying, and learn to love the syntax.

Easiest way to check if property is null or empty in java

Write a method isNullOrEmpty(String):

static boolean isNullOrEmpty(String s) {
  return s == null || s.trim().isEmpty()
  // Or return s == null || s.isBlank(); in Java 11+
}

So you can write:

return isNullOrEmpty(account.getAccesskeyid())
    || isNullOrEmpty(account.getAccount())
    /* etc */;

I consider this preferable to doing something that involves constructing streams or lists, because it's just simple: it's using very basic language features that are easily understandable by even a novice programmer.

In addition, it avoids evaluating all of the fields (e.g. passing String... ss to isNullOrEmpty, and then doing something on the array) because it short-circuits, in that it will stop as soon as it finds the first null or empty string.

It also does not require creation of any objects (like the implicit array, or a List in the case of Arrays.asList(...)) that are simply artefacts of invoking the method: trim() does potentially create objects, but this is "useful" work, insofar as this is necessary to evaluate the condition.

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