What does ?'' mean in Java

What does ?'' mean in Java

I'm happy to help you with that! However, I need to clarify that the combination of characters "???" is not a valid or standard notation in any programming language, including Java.

It's possible that you might be referring to another symbol or sequence of characters that has a specific meaning in Java. If that's the case, please provide more context or information about what you are trying to achieve or understand. I'll do my best to help you out!

That being said, if we were to assume that "???" is somehow related to null or absence of a value in Java, here's some general information about how null values work in the language:

In Java, the keyword null is used to represent the absence of any object value. This is often referred to as a null reference. When you assign null to an object reference, it indicates that the reference does not point to any actual object.

For example:

String str = null;

This declaration creates a string reference that does not point to any specific string object. Trying to access or manipulate a null reference will usually result in a runtime exception, such as a NullPointerException.

It's worth noting that Java also has some special null-safe methods and APIs that allow you to work with null values without throwing exceptions. These include methods like equals() and hashCode(), which can handle null inputs.

If you have any more specific questions about working with null values in Java or if there's anything else I can help you with, please feel free to ask!

What does ?'' mean in Java

I'd be happy to help!

The mysterious ?? symbols in Java are known as the "elvis operator" or "nully coalesce operator." It's a relatively new addition to the Java language, introduced in Java 12.

So, what does it mean?

In simple terms, the elvis operator is used to provide a default value if an expression or method call returns null. Think of it like saying, "Hey, I know you might not have an answer, so here's something else I can use instead."

The syntax is straightforward: ?? goes between two expressions or operands. The left side is evaluated first; if it's null, the right side is evaluated and its result is returned. If the left side is not null, the expression returns the value of the left side.

Here are some examples to illustrate this:

String name = person.getName() ?? "Unknown";

In this case, if person.getName() returns a non-null value, it will be assigned to name. But if it's null (or null-like), "Unknown" will be assigned instead.

Another example:

int result = myMethod() ?? 42;

Here, if myMethod() returns an integer value, it will be assigned to result. If the method call returns null or a null-like value, result will get the value 42 instead.

The elvis operator is particularly useful when working with optional values or APIs that return null in certain situations. It helps you avoid NullPointerExceptions and makes your code more robust.

Keep in mind that the right-hand side of the operator is only evaluated if the left side returns null. This means that the right side won't be executed unless absolutely necessary, which can improve performance in certain scenarios.

In summary, the ?? operator in Java is a concise way to provide a default value when an expression or method call might return null. It's a powerful tool for simplifying your code and making it more resilient!