what is the lateinit modifier for

Full Answer

See more

lateinit modifier

Normally, all non-nullable properties in Kotlin classes must be properly initialized. You can do it in several ways:

Lateinits vs nullables

The described possibility, despite being a great feature, may also be tempting to overuse in places where the initialization is not so certain (e.g. conditional or just too late ), making the code less null-aware, less predictable and more like Java, thus - naturally - you might be doubtful if certain usages are right or not.

How not to fool yourself?

Make the property nullable if it makes better sense and improves null safety. lateinit might be good if used properly but it has its cons as well. Don't make it a replacement for NullPointerException.

What is the lateinit keyword?

The lateinit keyword is used for late initialization of variables.

Why don't you initialize a variable?

There are many cases when you need to create a variable but you don't want to initialize it at the time of declaration/creation of the variable because you are sure that the variable will be initialized before its access/usage. One way of achieving this is by making the variable nullable like this:

What is the benefit of using lazy?

Now, the benefit of using lazy is that the object will be created only when it is called otherwise it will not be created. The other benefit of using lazy is that once the object is initialized, you will use the same object again when called. For example:

Can a lateinit variable be null?

NOTE: To use a lateinit variable, your variable should use var and NOT val. Lateinit is allowed for non-primitive data types only and the variable can't be of null type. Also, lateinit variable can be declared either inside the class or it can be a top-level property. For late initialization of variables.