Kotlin对象的懒加载方式by lazy 与 lateinit 异同详解

    private lateinit var name: String
    findViewById<Button>(R.id.btn_load).click {
        YYLogUtils.w("name:$name age:$age")
    }

    private lateinit var name: String
    findViewById<Button>(R.id.btn_load).click {
        if (this::name.isInitialized) {
           YYLogUtils.w("name:$name age:$age")
        }   
    }

   private var age: Int by Delegates.observable(18) { property, oldValue, newValue ->
        YYLogUtils.w("发生了回调 property:$property oldValue:$oldValue newValue：$newValue")
    }
    findViewById<Button>(R.id.btn_load).click {
        age = 25
        YYLogUtils.w("name:$name age:$age")
    }

public object Delegates {
    public fun <T : Any> notNull(): ReadWriteProperty<Any?, T> = NotNullVar()
    public inline fun <T> observable(initialValue: T, crossinline onChange: (property: KProperty<*>, oldValue: T, newValue: T) -> Unit):
            ReadWriteProperty<Any?, T> =
        object : ObservableProperty<T>(initialValue) {
            override fun afterChange(property: KProperty<*>, oldValue: T, newValue: T) = onChange(property, oldValue, newValue)
        }
    public inline fun <T> vetoable(initialValue: T, crossinline onChange: (property: KProperty<*>, oldValue: T, newValue: T) -> Boolean):
            ReadWriteProperty<Any?, T> =
        object : ObservableProperty<T>(initialValue) {
            override fun beforeChange(property: KProperty<*>, oldValue: T, newValue: T): Boolean = onChange(property, oldValue, newValue)
        }
}
private class NotNullVar<T : Any>() : ReadWriteProperty<Any?, T> {
    private var value: T? = null
    public override fun getValue(thisRef: Any?, property: KProperty<*>): T {
        return value ?: throw IllegalStateException("Property ${property.name} should be initialized before get.")
    }
    public override fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {
        this.value = value
    }
}

   private var age: Int  = 18
    findViewById<Button>(R.id.btn_load).click {
        age = 25
        YYLogUtils.w("name:$name age:$age")
    }

   private val age: Int by lazy { 18 / 2 }
    findViewById<Button>(R.id.btn_load).click {
        age = 25
        YYLogUtils.w("name:$name age:$age")
    }

public actual fun <T> lazy(initializer: () -> T): Lazy<T> = SynchronizedLazyImpl(initializer)
public actual fun <T> lazy(mode: LazyThreadSafetyMode, initializer: () -> T): Lazy<T> =
    when (mode) {
        LazyThreadSafetyMode.SYNCHRONIZED -> SynchronizedLazyImpl(initializer)
        LazyThreadSafetyMode.PUBLICATION -> SafePublicationLazyImpl(initializer)
        LazyThreadSafetyMode.NONE -> UnsafeLazyImpl(initializer)
    }
public actual fun <T> lazy(lock: Any?, initializer: () -> T): Lazy<T> = SynchronizedLazyImpl(initializer, lock)