Question

我在将respondlerview添加到constraintlayout然后从片段TestDriveFragment执行android.app.FragmentTransaction.replace到片段Experiment2Fragment我的下一个片段丢失了它的约束时遇到了问题，但是当我不使用recylerview时，一切都很好。

layout fragment_test_drive.XML：

<?xml version="1.0" encoding="utf-8"?>

    <layout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools">

        <android.support.constraint.ConstraintLayout
            android:id="@+id/drawer"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            tools:openDrawer="start">

            <android.support.v7.widget.RecyclerView
                android:id="@+id/rvAccount"
                android:layout_width="0dp"
                android:layout_height="0dp"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintHorizontal_bias="0.0"
                app:layout_constraintLeft_toLeftOf="parent"
                app:layout_constraintRight_toRightOf="parent"
                app:layout_constraintTop_toTopOf="parent"
                app:layout_constraintVertical_bias="0.0" />

            <android.support.design.widget.FloatingActionButton
                android:id="@+id/fabAccount"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginBottom="8dp"
                android:layout_marginEnd="8dp"
                android:layout_marginRight="8dp"
                android:clickable="true"
                app:backgroundTint="@color/colorAccent"
                app:fabSize="mini"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintRight_toRightOf="parent"
                app:srcCompat="@drawable/ic_add" />

        </android.support.constraint.ConstraintLayout>
    </layout>

然后我将此代码放在fab onclick上以更改为片段b：

MaintActivity.Java

public void fragmentTrans(Fragment a, boolean b){
    private Fragment fragment = a;
    private android.app.FragmentManager fragmentManager = getFragmentManager();
    private android.app.FragmentTransaction ft = fragmentManager.beginTransaction();
    ft.replace(R.id.fragment_frame,fragment);
    String backStateName = fragment.getClass().getName();
    if (b == true) {
        ft.addToBackStack(backStateName);
        Log.d(Tag, String.valueOf(b));
    }
    ft.commit();
}

TestDriveFragment.java

binding.fabAccount.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        private MainActivity activity = (MainActivity) getActivity();
    activity.fragmentTrans(new Experiment2Fragment(), true);
    }
});

两个结果屏幕截图：

Result fragment_experiment2 when Recycerview Removed from fragment_test_drive:

Result fragment_experiment2 when Recycerview used at fragment_test_drive

现在我通过将Recyclerview的可见性设置为Inivisbile来获得临时解决方案。但我仍然很好奇为什么会发生这种情况

recyclerview使约束布局失去它的约束

0 个答案: