lateinit属性尚未初始化

Question

我有一个自定义linearlayout类,当我想创建这个类的实例时,我得到一个错误lateinit属性尚未初始化 我正在使用最新版本的butterknife库

这是我的kotlin课程

class MenuItemView : LinearLayout {

@BindView(R.id.menu_title_text_view_id)
lateinit var menuTitleTextView : CTextBasic

constructor(ctx: Context) : super(ctx) {
}

init {
    val view = LayoutInflater.from(context).inflate(R.layout.menu_item,this)
    ButterKnife.bind(this,view)
}

constructor(ctx: Context, attrs: AttributeSet) : super(ctx, attrs) {
    val menuAttrs = context.theme.obtainStyledAttributes(attrs, R.styleable.MenuItemView, 0, 0)
    try {
        val title: String = menuAttrs.getString(R.styleable.MenuItemView_menu_title)
        menuTitleTextView.text = title
    }catch (e : Exception){
        e.printStackTrace()
    }finally {
        menuAttrs.recycle()
    }
}
fun setTitle( title : String){
    menuTitleTextView.text = title
}
}

这是错误日志

    kotlin.UninitializedPropertyAccessException: lateinit property menuTitleTextView has not been initialized
at com.leavigstone.liberali.ui.custom.menu.MenuItemView.setTitle(MenuItemView.kt:48)
at com.leavigstone.liberali.ui.activities.MainActivity.onAddButtonClick(MainActivity.java:142)
at com.leavigstone.liberali.ui.activities.MainActivity_ViewBinding$3.doClick(MainActivity_ViewBinding.java:54)
at butterknife.internal.DebouncingOnClickListener.onClick(DebouncingOnClickListener.java:22)
at android.view.View.performClick(View.java:4780)
at android.view.View$PerformClick.run(View.java:19866)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

Answer 1

如果你不想使用任何第三方库,你可以添加这些扩展函数(我倾向于有一个ContextExtensions.kt或ViewExtensions.kt用于Context或View相关的扩展函数),然后放入它

inline fun <reified T : View> View.find(id: Int): T = findViewById(id) as T
inline fun <reified T : View> Activity.find(id: Int): T = findViewById(id) as T
inline fun <reified T : View> Fragment.find(id: Int): T = view?.findViewById(id) as T

这些让你调用find从内Activity,Fragment和View秒.所以在你的班级而不是

@BindView(R.id.menu_title_text_view_id) lateinit var menuTitleTextView : CTextBasic

你可以有

val menuTitleTextView by lazy { find<CTextBasic>(R.id.menu_title_text_view_id) }

对于像UI这样的东西,最好val不要var在他们不需要改变的时候.作为编程的一般规则,尽量使事物尽可能不变,你会得到更少的错误.

Answer 2

使用Kotterknife为 Kotlin 进行黄油刀式视图绑定。

然后你可以绑定你的视图

val menuTitleTextView: CTextBasic by bindView(R.id.menu_title_text_view_id)