java.lang.RuntimeException：調用觀察者方法失敗

Question

請幫我解決我的問題。 具有這些相同代碼的應用程序運行良好，但現在每當我嘗試從概覽片段導航到詳細信息片段時，應用程序就會崩潰。

我沒有更改任何代碼行，應用程序仍然崩潰。 請幫我解決一下這個。

這是日志：

    Process: com.example.marsrealestate, PID: 4158
    java.lang.RuntimeException: Failed to call observer method
        at androidx.lifecycle.ClassesInfoCache$MethodReference.invokeCallback(ClassesInfoCache.java:226)
        at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeMethodsForEvent(ClassesInfoCache.java:194)
        at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeCallbacks(ClassesInfoCache.java:185)
        at androidx.lifecycle.ReflectiveGenericLifecycleObserver.onStateChanged(ReflectiveGenericLifecycleObserver.java:37)
        at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361)
        at androidx.lifecycle.LifecycleRegistry.forwardPass(LifecycleRegistry.java:300)
        at androidx.lifecycle.LifecycleRegistry.sync(LifecycleRegistry.java:339)
        at androidx.lifecycle.LifecycleRegistry.moveToState(LifecycleRegistry.java:145)
        at androidx.lifecycle.LifecycleRegistry.handleLifecycleEvent(LifecycleRegistry.java:131)
        at androidx.fragment.app.Fragment.performStart(Fragment.java:2735)
        at androidx.fragment.app.FragmentStateManager.start(FragmentStateManager.java:365)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1194)
        at androidx.fragment.app.FragmentManager.addAddedFragments(FragmentManager.java:2224)
        at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1997)
        at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1953)
        at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1849)
        at androidx.fragment.app.FragmentManager$4.run(FragmentManager.java:413)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:201)
        at android.app.ActivityThread.main(ActivityThread.java:6806)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)
     Caused by: java.util.IllegalFormatPrecisionException: 79
        at java.util.Formatter$FormatSpecifierParser.<init>(Formatter.java:2613)
        at java.util.Formatter.parse(Formatter.java:2557)
        at java.util.Formatter.format(Formatter.java:2504)
        at java.util.Formatter.format(Formatter.java:2458)
        at java.lang.String.format(String.java:2883)
        at android.content.res.Resources.getString(Resources.java:478)
        at android.content.Context.getString(Context.java:603)
        at com.example.marsrealestate.detail.DetailViewModel$displayPropertyPrice$1.apply(DetailViewModel.kt:26)
        at com.example.marsrealestate.detail.DetailViewModel$displayPropertyPrice$1.apply(DetailViewModel.kt:11)
        at androidx.lifecycle.Transformations$1.onChanged(Transformations.java:76)
        at androidx.lifecycle.MediatorLiveData$Source.onChanged(MediatorLiveData.java:152)
        at androidx.lifecycle.LiveData.considerNotify(LiveData.java:131)
        at androidx.lifecycle.LiveData.dispatchingValue(LiveData.java:144)
        at androidx.lifecycle.LiveData$ObserverWrapper.activeStateChanged(LiveData.java:443)
        at androidx.lifecycle.LiveData.observeForever(LiveData.java:232)
        at androidx.lifecycle.MediatorLiveData$Source.plug(MediatorLiveData.java:141)
        at androidx.lifecycle.MediatorLiveData.onActive(MediatorLiveData.java:118)
        at androidx.lifecycle.LiveData$ObserverWrapper.activeStateChanged(LiveData.java:437)
        at androidx.lifecycle.LiveData$LifecycleBoundObserver.onStateChanged(LiveData.java:395)
        at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361)
        at androidx.lifecycle.LifecycleRegistry.addObserver(LifecycleRegistry.java:188)
        at androidx.lifecycle.LiveData.observe(LiveData.java:203)
        at androidx.databinding.ViewDataBinding$LiveDataListener.addListener(ViewDataBinding.java:1626)
        at androidx.databinding.ViewDataBinding$LiveDataListener.addListener(ViewDataBinding.java:1574)
        at androidx.databinding.WeakListener.setTarget(WeakListener.java:85)
2022-02-05 15:43:34.998 4158-4158/com.example.marsrealestate E/AndroidRuntime:     at androidx.databinding.ViewDataBinding.registerTo(ViewDataBinding.java:729)
        at androidx.databinding.ViewDataBinding.updateRegistration(ViewDataBinding.java:653)
        at androidx.databinding.ViewDataBinding.updateLiveDataRegistration(ViewDataBinding.java:691)
        at com.example.marsrealestate.databinding.FragmentDetailBindingImpl.executeBindings(FragmentDetailBindingImpl.java:183)
        at androidx.databinding.ViewDataBinding.executeBindingsInternal(ViewDataBinding.java:512)
        at androidx.databinding.ViewDataBinding.executePendingBindings(ViewDataBinding.java:484)
        at androidx.databinding.ViewDataBinding$OnStartListener.onStart(ViewDataBinding.java:1706)
        at java.lang.reflect.Method.invoke(Native Method)
        at androidx.lifecycle.ClassesInfoCache$MethodReference.invokeCallback(ClassesInfoCache.java:216)
            ... 23 more

這是 DetailViewModel class：

class DetailViewModel(marsProperty: MarsProperty, app: Application) : AndroidViewModel(app) {

    private val _selectedProperty = MutableLiveData<MarsProperty>()
    val selectedProperty : LiveData<MarsProperty>
    get() = _selectedProperty

    init {
        _selectedProperty.value = marsProperty
    }

    /**
     * This transformation tests whether the selected property is a rental.If the property is a rental,
     * the transformation chooses the appropriate string from the resources with a Kotlin when {} switch.
     */
    val displayPropertyPrice = Transformations.map(selectedProperty){
        app.applicationContext.getString(
            when(it.isRental){
                true -> R.string.display_price_monthly_rental
                false -> R.string.display_price
            }, it.price)
    }

    /**
     * This transformation concatenates multiple string resources,
     * based on whether the property type is a rental.
     */
    val displayPropertyType = Transformations.map(selectedProperty){
        app.applicationContext.getString(R.string.display_type,
        app.applicationContext.getString(
            when(it.isRental){
                true -> R.string.type_rent
                false -> R.string.type_sale
            }))
    }
}

錯誤在這部分：

app.applicationContext.getString(
            when(it.isRental){
                true -> R.string.display_price_monthly_rental
                false -> R.string.display_price
            }, it.price)

這是上面的兩個字符串：

<string name="display_price_monthly_rental">$%,.Of/month</string>
    <string name="display_price">$%,.Of</string>

我研究了 StackOverflow 中的所有示例，但沒有解決我的問題。 請幫忙。

Answer 1

我做了同樣的代碼實驗室，我發現價格必須是 Float 類型，所以我有這樣的修復

        app.applicationContext.getString(
            when (it.isRental) {
                true -> R.string.display_price_monthly_rental
                false -> R.string.display_price
            }, it.price.toFloat())