回收器滑动刷新布局中的视图未"wrap_content"

Question

我有一个RecyclerView作为SwipeRefreshLayout的唯一孩子，我想要RecyClerview wrap_content。当我设置两个wrap_content时，它不起作用。RecyclerView较少的项目也match_parent。当我删除SwipeRefreshLayout时，RecyclerView将wrap_content。谁能帮我？我的英语很差，也许您无法理解。有人可以帮我吗？非常感谢。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/container_v"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.v4.widget.SwipeRefreshLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#00ffff">
        <android.support.v7.widget.RecyclerView
            android:id="@+id/recycler_view"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="#ff00ff">
    </android.support.v7.widget.RecyclerView>
</android.support.v4.widget.SwipeRefreshLayout>

Answer 1

最后，我解决了。从这个答案

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/container_v"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.v4.widget.SwipeRefreshLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#00ffff">
        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="vertical">
            <android.support.v7.widget.RecyclerView
                android:id="@+id/recycler_view"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="#ff00ff"/>
        </LinearLayout>
    </android.support.v4.widget.SwipeRefreshLayout>
</LinearLayout>

Answer 2

关键是使用布局包装循环。swiperefreshlayout的bacause使用 MeasureSpec.EXACTLY模式测量mtarget size当onmeasure（）：

    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (mTarget == null) {
            ensureTarget();
        }
        if (mTarget == null) {
            return;
        }
        mTarget.measure(MeasureSpec.makeMeasureSpec(
                getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),
                MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(
                getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), MeasureSpec.EXACTLY));
        ......
    }

和mtarget是SwipereFreshlayout的第一个孩子视图。因此，这将导致mtarget始终与父母匹配。

    private void ensureTarget() {
        // Don't bother getting the parent height if the parent hasn't been laid
        // out yet.
        if (mTarget == null) {
            for (int i = 0; i < getChildCount(); i++) {
                View child = getChildAt(i);
                if (!child.equals(mCircleView)) {
                    mTarget = child;
                    break;
                }
            }
        }
    }

framelayout之所以使用，是因为它更轻巧。

    <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <FrameLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">
            <androidx.recyclerview.widget.RecyclerView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:paddingTop="10dp"
                android:paddingBottom="10dp"
                tools:itemCount="2"
                tools:listitem="@layout/item_msg_detail_text_style" />
        </FrameLayout>
    </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>