小编Max*_*axB的帖子

由于两个片段之间的工具栏中的后退按钮的实现困难，我决定开始熟悉Navigation Graph。但我收到一个错误

Views added to a FragmentContainerView must be associated with a Fragment. View android.widget.RelativeLayout{...} is not associated with a Fragment.

这是 .xml 文件，其中包含nav_host_fragment：

<?xml version="1.0" encoding="utf-8"?>
<layout ...
    <fragment
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:name="androidx.navigation.fragment.NavHostFragment"
        app:navGraph="@navigation/nav_graph"
        app:defaultNavHost="true">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/colorBlack"
            android:clickable="@{viewModel.isSearching ? false : true}"
            android:focusable="@{viewModel.isSearching ? false : true}">

            <androidx.recyclerview.widget.RecyclerView
                android:id="@+id/recent_recyclerView"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginStart="4dp"
                android:layout_marginTop="4dp"
                android:layout_marginEnd="4dp"
                android:layout_marginBottom="4dp"
                android:background="@color/colorBlack"
                tools:itemCount="10"
                tools:listitem="@layout/search_user_layout" />

            <androidx.recyclerview.widget.RecyclerView
                android:id="@+id/search_recyclerView"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginStart="4dp"
                android:layout_marginTop="4dp"
                android:layout_marginEnd="4dp"
                android:layout_marginBottom="4dp"
                android:background="@color/colorBlack"
                android:visibility="gone"
                tools:itemCount="10"
                tools:listitem="@layout/search_user_layout" />

            <ProgressBar
                android:id="@+id/loading"
                android:layout_width="48dp"
                android:layout_height="48dp" …

当我使用

buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }

一切都很完美。

但如果改为

buildTypes {
        release {
            minifyEnabled true
            useProguard true
            shrinkResources true
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }

我收到解析错误。

我的解析类：

data class SearchItem(
    @SerializedName("position") val position: Long,
    @SerializedName("user") val user: String?
) {
    fun getId(): Long {
        return 0L
    }
}

data class SearchResponse(
    @SerializedName("list") val list: List<SearchItem>,
    @SerializedName("has_more") val has_more: Boolean,
    @SerializedName("rank_token") val rank_token: String,
    @SerializedName("status") val status: String
)

这里我使用gson：

val searchResponse = Gson().fromJson(jsonObject.toString(), SearchResponse::class.java)

在proguard-rules.pro …

我有两个片段，我想使用操作栏中的后退按钮在它们之间创建交互。理想情况下，我希望保存先前片段的状态。我只能找到有关活动的信息。

对于片段我发现了这个

private fun setupBackButton() {
        if (activity is AppCompatActivity) {
            (activity as AppCompatActivity?)?.supportActionBar?.setDisplayHomeAsUpEnabled(true)
        }
    }

但它只显示后退按钮，点击没有任何反应。

编辑

在第一个片段中，我将第二个片段称为：

val fragment = UserContentFragment()
fragment.setUser(item.user)

if (fragmentManager != null) {
    fragmentManager!!
      .beginTransaction()
      .replace(R.id.main_layout, fragment)
      .addToBackStack(null)
      .commit()
}

这是我的UserContentFragment第二个片段：

class UserContentFragment : Fragment() {

    private lateinit var user: SearchUser

    fun setUser(user: SearchUser) {
        this.user = user
    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        val root = inflater.inflate(R.layout.fragment_user_content, container, false)

        val userImage = root.findViewById(R.id.user_img) as ImageView
        if …

我创建了 stackView 并向其添加了三个标签。我还设置了这些限制

let nameLabel = UILabel()
//set .text, .mode and other for nameLabel
let ellipsisLabel = UILabel()
//set .text, .mode and other for ellipsisLabel
let amountAndMeasureLabel = UILabel()
//set .text, .mode and other for amountAndMeasureLabel

for label in [nameLabel, ellipsisLabel, amountAndMeasureLabel] {
                stackView.addArrangedSubview(label)
            }
NSLayoutConstraint.activate([
                nameLabel.leadingAnchor.constraint(equalTo: stackView.leadingAnchor, constant: 0.0),
                nameLabel.trailingAnchor.constraint(equalTo: ellipsisLabel.leadingAnchor, constant: 0.0),
                nameLabel.widthAnchor.constraint(equalToConstant: nameLabel.intrinsicContentSize.width),
                amountAndMeasureLabel.leadingAnchor.constraint(equalTo: ellipsisLabel.trailingAnchor, constant: 0.0),
                amountAndMeasureLabel.trailingAnchor.constraint(equalTo: stackView.trailingAnchor, constant: 0.0),
                amountAndMeasureLabel.widthAnchor.constraint(equalToConstant: amountAndMeasureLabel.intrinsicContentSize.width)
            ])

nameLabel.frame.width // 0
ellipsisLabel.frame.width // 0
amountAndMeasureLabel.frame.width // 0

我将在 .xib 上演示情况以便更好地理解（我不使用这个 .xib） …