lateinit: lazy initialization
java：
private LoginPresenter loginPresenter;
kotlin：
private lateinit var loginPresenter: LoginPresenter
by lazy: lazy initialization
Lazy initialization is a common pattern where parts of the object are not created on demand until the property is first accessed, when the initialization process consumes a lot of resources and the data is not always needed when using the object , this is very useful
val nameB: String by lazy {
println("getLazy")
"123"
}
println(nameB)
println(nameB)
Enter the result:
System.out: getLazy
System.out: 123
System.out: 123
The first thing to note is:
- by lazy can only act on properties marked with the val keyword
- The contents of "lazy{}" will be initialized when the property is used
- And when the property is called again, only the result will be obtained, and the running process of lazy{} will not be executed again