仅当 minifyEnabled 和 LifeCycle v 2.1.0 时，应用程序在创建 ViewModel 时崩溃

Question

在使用 lazy{} 创建视图模型时，我的应用程序在启动时崩溃并显示 LinkageError。崩溃仅在以下情况下发生：

1. minifyEnabled 在 build.gradle 中设置为 true，并且
2. 我用的是 ver. 2.1.0 个生命周期组件。它适用于 lifecycle-2.0.0 和 minifyEnabled

    def lifecycle_version = '2.1.0'
    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version"
    implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version"

另外，崩溃只发生在其中一个视图模型上。在此之前触摸的同一 activity 中的其他视图模型不会导致应用程序崩溃。

---

崩溃发生在第二行：

    private val searchStackViewModel by lazy {
        ViewModelProviders.of(this)[SearchStateViewModel::class.java]
    }

SearchStateViewModel是：

class SearchStateViewModel : ViewModel() {

    // Live data that initialises to empty stack with SearchStack.init
    private val privateStack = MutableLiveData<SearchStack>().apply {
        value = SearchStack()
    }

    // Observable view of search stack so it can't be directly modified
    internal val stateStack : LiveData<SearchStack> = privateStack

    /**
     * Add state to stack
     */
    fun add(searchState: SearchState) {
        val current = privateStack.value ?: SearchStack()
        current.add(searchState)
        privateStack.value = current
    }

    /**
     * Clear stack
     */
    fun clear() {
        val current = privateStack.value ?: SearchStack()
        current.clear()
        privateStack.value = current
    }

    /**
     * Clear stack, then add current state as the only state
     */
    fun clearThenAdd(searchState: SearchState) {
        val current = privateStack.value ?: SearchStack()
        current.clear()
        current.add(searchState)
        privateStack.value = current
    }

    /**
     * Get currentState search state, without changing the stack
     */
    fun currentState(): SearchState {
        return privateStack.value?.last() ?: SearchState()
    }

    /**
     * Return currentState search state, and remove it from the stack
     */
    fun pop(): SearchState {
        val current = privateStack.value ?: SearchStack()
        val poppedState = current.pop()
        privateStack.value = current
        return poppedState
    }
}

SearchStack 只是一个 ArrayList:

class SearchStack : ArrayList<SearchState>() {

    init {
        add(SearchState())
    }


    fun pop(): SearchState = if (lastIndex > 0) removeAt(lastIndex) else last()


    override fun clear() {
        super.clear()
        add(SearchState())
    }


    override fun add(element: SearchState): Boolean {
        if (element == lastOrNull())
            return false
        return super.add(element)
    }
}

而SearchState是一个数据class:

@Parcelize
data class SearchState(
        val searchTerm: String = "",
        val isComplete: Boolean? = null,
        val dueOnly: Boolean = false,
        val aliveOnly: Boolean = true,
        val priority: Char? = null,
        val project: String? = null,
        val priorityMatchType: PriorityMatchType? = null,
        val name: String = "",
        val hideThresholdTasks: Boolean = true,
        val sortOrder: Int = -1,
        val sortOrderString: String? = null
                      ) : Parcelable {

    enum class PriorityMatchType {
        GREATOR,
        LESSOR,
        EXACT
    }

    enum class TaskState {
        DUE,
        PENDING,
        COMPLETED,
        ALL
    }

---

堆栈跟踪：

FATAL EXCEPTION: main
    Process: net.c306.ttsuper, PID: 7380
    java.lang.LinkageError: i.a.a.o.b
1 >>    at net.c306.ttsuper.view.ui.MainActivity$v.b(SourceFile:182)
        at net.c306.ttsuper.view.ui.MainActivity$v.b(SourceFile:159)
        at g.j.a(SourceFile:74)
        at net.c306.ttsuper.view.ui.MainActivity.F(SourceFile)
2 >>    at net.c306.ttsuper.view.ui.MainActivity.c(SourceFile:1839)
        at net.c306.ttsuper.view.ui.MainActivity.a(SourceFile:1993)
        at net.c306.ttsuper.view.ui.MainActivity.a(SourceFile:1967)
        at net.c306.ttsuper.view.ui.MainActivity.onCreate(SourceFile:386)
        at android.app.Activity.performCreate(Activity.java:6251)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
        at android.app.ActivityThread.-wrap11(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:148)
        at android.app.ActivityThread.main(ActivityThread.java:5417)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

标记为 (1) 的行是发生崩溃的 ViewModel 的惰性创建。
标记为 (2) 的行是启动惰性创建的 ViewModel 的第一次访问：

val lastState = searchStackViewModel.currentState()

Answer 1

我可能已经解决了这个问题。事实证明，在 lifecycle-2.0.0 中，ViewModel class 有一个 public 方法 clear():

    @MainThread
    final void clear() {
        mCleared = true;
        // Since clear() is final, this method is still called on mock objects
        // and in those cases, mBagOfTags is null. It'll always be empty though
        // because setTagIfAbsent and getTag are not final so we can skip
        // clearing it
        if (mBagOfTags != null) {
            synchronized (mBagOfTags) {
                for (Object value : mBagOfTags.values()) {
                    // see comment for the similar call in setTagIfAbsent
                    closeWithRuntimeException(value);
                }
            }
        }
        onCleared();
    }

我的SearchStackViewModel还有一个完全不相关的clear()方法。

    /**
     * Clear stack
     */
    fun clear() {
        val current = privateStack.value ?: SearchStack()
        current.clear()
        privateStack.value = current
    }

当minifyEnabled打开时，两者之间似乎存在冲突，因此出现链接错误。我重命名了我的方法，崩溃停止了。