Java long object null

How to check a long for null in java?

When working with Java, it is possible to encounter a scenario where you need to check if a Long variable is null. A Long is a wrapper class for the primitive type long, and unlike a primitive type, it can be assigned a null value. It is important to check for a null value when working with Long objects to avoid a NullPointerException.

Method 1: Using == operator

To check if a Long variable is null in Java using the == operator, you can simply compare it with the null value. Here is an example code snippet:

Long myLong = null; if (myLong == null)  System.out.println("myLong is null"); > else  System.out.println("myLong is not null"); >

This code checks if the myLong variable is null by comparing it with the null value using the == operator. If it is null, it prints «myLong is null», otherwise it prints «myLong is not null».

You can also use the ternary operator to do the same check in a more concise way:

Long myLong = null; String result = (myLong == null) ? "myLong is null" : "myLong is not null"; System.out.println(result);

This code assigns the result of the ternary operator to the result variable, which is either «myLong is null» or «myLong is not null» depending on the value of myLong .

In summary, to check if a Long variable is null in Java using the == operator, you can simply compare it with the null value. The ternary operator can also be used to do the same check in a more concise way.

Method 2: Using equals() method

To check if a Long variable is null in Java using the equals() method, you can compare it with the null reference. Here is an example code:

Long myLong = null; if (myLong == null || myLong.equals(null))  System.out.println("myLong is null"); > else  System.out.println("myLong is not null"); >

In this code, we first check if myLong is null using the == operator. If it is null, then we know that it is indeed null and we print a message saying so. If it is not null, we call the equals() method on it and pass in the null reference. The equals() method returns true if the object being compared to null is also null , so if myLong is null, the equals() method will return true and we print a message saying so. If myLong is not null, the equals() method will return false and we know that myLong is not null.

Long myLong = 123L; if (myLong == null || myLong.equals(null))  System.out.println("myLong is null"); > else  System.out.println("myLong is not null"); >

In this code, we assign a non-null value to myLong and then check if it is null using the same method as before. Since myLong is not null, the equals() method will return false and we print a message saying that myLong is not null.

In summary, to check if a Long variable is null in Java using the equals() method, you can compare it with the null reference using either the == operator or the equals() method itself.

Method 3: Using Objects.isNull() method

To check if a Long variable is null in Java, you can use the Objects.isNull() method. This method returns true if the specified object is null , otherwise false . Here’s an example code snippet that demonstrates how to use this method:

Long value = null; if (Objects.isNull(value))  System.out.println("The value is null"); > else  System.out.println("The value is not null"); >

In this example, we declare a Long variable named value and initialize it to null . We then use the Objects.isNull() method to check if the value is null . Since the value is indeed null , the output of this code will be «The value is null».

Here’s another example that shows how to check if a Long variable is not null:

Long value = 10L; if (!Objects.isNull(value))  System.out.println("The value is not null"); > else  System.out.println("The value is null"); >

In this example, we initialize the value variable to 10L . We then use the negation operator ( ! ) to check if the value is not null . Since the value is not null , the output of this code will be «The value is not null».

That’s it! By using the Objects.isNull() method, you can easily check if a Long variable is null or not in Java.

Method 4: Using Optional.ofNullable() method

To check if a Long value is null in Java, we can use the Optional.ofNullable() method. This method returns an Optional object that contains the specified value if it is not null, or an empty Optional if the value is null. We can then use the isPresent() method to check if the Optional contains a value.

Here’s an example code snippet that demonstrates how to use the Optional.ofNullable() method to check if a Long value is null:

Long value = null; OptionalLong> optionalValue = Optional.ofNullable(value); if (optionalValue.isPresent())  System.out.println("Value is not null: " + optionalValue.get()); > else  System.out.println("Value is null"); >

In this example, we first declare a Long variable value and initialize it to null. We then create an Optional object optionalValue using the Optional.ofNullable() method and pass in the value variable. Since value is null, optionalValue will be an empty Optional .

We then use the isPresent() method to check if optionalValue contains a value. Since it is empty, the isPresent() method will return false and we print out «Value is null».

Here’s another example that demonstrates how to use the Optional.ofNullable() method with a non-null Long value:

Long value = 123L; OptionalLong> optionalValue = Optional.ofNullable(value); if (optionalValue.isPresent())  System.out.println("Value is not null: " + optionalValue.get()); > else  System.out.println("Value is null"); >

In this example, we initialize the value variable to a non-null Long value of 123L. When we create the Optional object optionalValue using the Optional.ofNullable() method, optionalValue will contain the value 123L.

We then use the isPresent() method to check if optionalValue contains a value. Since it does, the isPresent() method will return true and we print out «Value is not null: 123».

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