android-studio - 通过导航从另一个片段移回后，在片段中动态添加视图不会持续存在

Question

我在片段中动态添加视图，效果很好，但是当我导航到另一个片段并返回到第一个片段时，所有布局都设置为初始布局（不存在动态添加的视图）。所以在这里我必须保存 UI 状态，直到我的片段的父活动没有关闭。

初始片段类代码

package com.hp.billingapp.ui.billfragment;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AutoCompleteTextView;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.LinearLayout;
import android.widget.TextView;
import androidx.constraintlayout.widget.ConstraintLayout;
import androidx.fragment.app.Fragment;
import androidx.navigation.Navigation;
import com.google.android.material.snackbar.Snackbar;
import com.google.android.material.textfield.TextInputEditText;
import com.hp.billingapp.R;
import com.hp.billingapp.ui.BillingActivity;
public class OrderFragment extends Fragment {
    Button pay, buttonAdd;
    LinearLayout itemLayout;
    Integer item = 1, emptyChk;
    Float total;
    ConstraintLayout constraintLayout;
    Integer layoutId;

    public OrderFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View root = inflater.inflate(R.layout.fragment_order, container, false);
        pay = root.findViewById(R.id.pay);
        pay.setOnClickListener(v -> {
            datafetch(root);
        });
        itemLayout = root.findViewById(R.id.itemLayout);
        constraintLayout = root.findViewById(R.id.constraintLayout);
        buttonAdd = root.findViewById(R.id.button);
        buttonAdd.setOnClickListener(v -> addView());
        return root;
    }

    private void datafetch(View root) {
        Log.i("heetcount", String.valueOf(itemLayout.getChildCount()));
        emptyChk = 0;
        total = (float) 0;
        for (int i = 0; i < itemLayout.getChildCount(); i++) {
            View itemView = itemLayout.getChildAt(i);
            TextView number = itemView.findViewById(R.id.number);
            AutoCompleteTextView name = itemView.findViewById(R.id.namet);
            TextInputEditText price = itemView.findViewById(R.id.pricet);
            AutoCompleteTextView type = itemView.findViewById(R.id.typet);
            if (name.getText().toString().isEmpty() || price.getText().toString().isEmpty() || 
            type.getText().toString().isEmpty()) {
                Snackbar.make(constraintLayout, "Please fill the required fields", 
            Snackbar.LENGTH_SHORT).show();
                emptyChk += 1;
            } else {
                total = total + Float.parseFloat(price.getText().toString().trim());
            }
        }
        if (emptyChk == 0) {
            Log.i("heettotal", total.toString());
            OrderFragmentDirections.ActionOrderFragmentToBillingFragment action = 
            OrderFragmentDirections.actionOrderFragmentToBillingFragment(total);
            Navigation.findNavController(root).navigate(action);
            
            ((BillingActivity) getActivity()).heading("b");
        }

    }

    private void addView() {
        item = item + 1;
        String text = "Item " + item;
        View itemView = getLayoutInflater().inflate(R.layout.item_layout, null, false);
        TextView number = itemView.findViewById(R.id.number);
        ImageButton remove = itemView.findViewById(R.id.remove);
        AutoCompleteTextView nametiet = itemView.findViewById(R.id.namet);
        AutoCompleteTextView typetiet = itemView.findViewById(R.id.typet);
        TextInputEditText pricetiet = itemView.findViewById(R.id.pricet);
        number.setText(text);
        remove.setOnClickListener(v -> removeView(itemView));
        itemLayout.addView(itemView);
    }

    private void removeView(View itemView) {
        Log.i("heetview", String.valueOf(itemView));
        itemLayout.removeView(itemView);
    }

}

初始片段布局代码

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/constraintLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/backdropcenter"
    android:theme="@style/Theme.MaterialComponents.NoActionBar"
    tools:context=".ui.billfragment.OrderFragment">

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="80dp"
        android:overScrollMode="never">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <LinearLayout
                android:id="@+id/itemLayout"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical">

                <include layout="@layout/item_layout" />
            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical">

                <Button
                    android:id="@+id/button"
                    android:layout_width="300dp"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center"
                    android:layout_marginTop="50dp"
                    android:background="@drawable/allcornerround"
                    android:fontFamily="@font/montserrat"
                    android:text="Add Item"
                    android:textAllCaps="false"
                    android:textSize="18sp"
                    android:textStyle="bold" />

                <Button
                    android:id="@+id/pay"
                    android:layout_width="300dp"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center"
                    android:layout_marginTop="20dp"
                    android:background="@drawable/allcornerround"
                    android:fontFamily="@font/montserrat"
                    android:text="Pay"
                    android:textAllCaps="false"
                    android:textSize="18sp"
                    android:textStyle="bold" />
            </LinearLayout>
        </LinearLayout>
    </ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>

动态添加的布局代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:theme="@style/Theme.MaterialComponents.NoActionBar">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/number"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:layout_weight="1"
            android:text="Item 1"
            android:textColor="#191b20"
            android:textSize="18sp"
            android:textStyle="bold" />

        <ImageButton
            android:id="@+id/remove"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="3"
            android:background="#00000000"
            android:src="@drawable/ic_close"
            app:tint="#191b20" />
    </LinearLayout>

    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/nametil"
        style="@style/InputDropDown"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="10dp"
        android:layout_marginTop="10dp"
        android:layout_marginEnd="10dp"
        android:elevation="5dp"
        android:hint="Item Name"
        app:boxBackgroundMode="filled"
        app:endIconMode="dropdown_menu"
        app:endIconTint="#AA191b20"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/nametil">

        <AutoCompleteTextView
            android:id="@+id/namet"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fontFamily="@font/montserrat"
            android:gravity="center_vertical"
            android:inputType="none"
            android:textColor="#191b20"
            android:textCursorDrawable="@drawable/cursor"
            android:textSize="18sp" />

    </com.google.android.material.textfield.TextInputLayout>

    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/typetil"
        style="@style/InputDropDown"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="10dp"
        android:layout_marginTop="10dp"
        android:layout_marginEnd="10dp"
        android:elevation="5dp"
        android:hint="Type"
        app:boxBackgroundMode="filled"
        app:endIconMode="dropdown_menu"
        app:endIconTint="#AA191b20"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/nametil">

        <AutoCompleteTextView
            android:id="@+id/typet"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fontFamily="@font/montserrat"
            android:gravity="center_vertical"
            android:inputType="none"
            android:textColor="#191b20"
            android:textCursorDrawable="@drawable/cursor"
            android:textSize="18sp" />

    </com.google.android.material.textfield.TextInputLayout>

    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/pricetil"
        style="@style/InputText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="10dp"
        android:layout_marginTop="10dp"
        android:layout_marginEnd="10dp"
        android:elevation="5dp"
        android:hint="Price"
        app:boxBackgroundMode="filled"
        app:endIconMode="clear_text"
        app:endIconTint="#AA191b20">

        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/pricet"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fontFamily="@font/montserrat"
            android:gravity="center_vertical"
            android:inputType="numberDecimal"
            android:textColor="#191b20"
            android:textCursorDrawable="@drawable/cursor"
            android:textSize="18sp" />
    </com.google.android.material.textfield.TextInputLayout>

</LinearLayout>

问题快照

第一个片段开始时的初始状态

动态查看添加和信息填充

从另一个片段返回后的第一个片段