Question

我正在尝试创建一个待办事项列表，就像“谷歌保持”Android应用程序一样。基本上，我需要一个带有2个列表的滚动布局：一个选中的项目，以及一个未选中的项目。未选中的列表应该有一个选项来拖动和放大放下物品以改变它们的位置。我唯一的问题是我不能在recyclerview中使用width = wrap_content，而我发现的layoutManager实现在我尝试拖动时会让应用程序崩溃。下降。

对于阻力＆amp;我使用this library.

我的布局：

<ScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true"
tools:context="views.fragments.ItemsFragment">

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

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

        <AutoCompleteTextView
            android:id="@+id/fragment_items_atv_name"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="wrap_content" />

        <Button
            android:id="@+id/fragment_items_btn_add"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="8dp"
            android:text="@string/add" />

    </LinearLayout>

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

        <android.support.v7.widget.RecyclerView
            android:id="@+id/fragment_items_lv_unchecked_list"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <android.support.v7.widget.RecyclerView
            android:id="@+id/fragment_items_lv_checked_list"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <TextView
            android:id="@+id/fragment_items_tv_empty"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="Empty list"
            android:visibility="gone" />

    </LinearLayout>
</LinearLayout>
</ScrollView>

我使用的布局管理器

public class MyLinearLayoutManager extends LinearLayoutManager {

public MyLinearLayoutManager(Context context)    {
    super(context, VERTICAL, false);
}

private int[] mMeasuredDimension = new int[2];

@Override
public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
                      int widthSpec, int heightSpec) {
    final int widthMode = View.MeasureSpec.getMode(widthSpec);
    final int heightMode = View.MeasureSpec.getMode(heightSpec);
    final int widthSize = View.MeasureSpec.getSize(widthSpec);
    final int heightSize = View.MeasureSpec.getSize(heightSpec);
    int width = 0;
    int height = 0;
    for (int i = 0; i < getItemCount(); i++) {
        measureScrapChild(recycler, i,
                View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                mMeasuredDimension);

        if (getOrientation() == HORIZONTAL) {
            width = width + mMeasuredDimension[0];
            if (i == 0) {
                height = mMeasuredDimension[1];
            }
        } else {
            height = height + mMeasuredDimension[1];
            if (i == 0) {
                width = mMeasuredDimension[0];
            }
        }
    }
    switch (widthMode) {
        case View.MeasureSpec.EXACTLY:
            width = widthSize;
        case View.MeasureSpec.AT_MOST:
        case View.MeasureSpec.UNSPECIFIED:
    }

    switch (heightMode) {
        case View.MeasureSpec.EXACTLY:
            height = heightSize;
        case View.MeasureSpec.AT_MOST:
        case View.MeasureSpec.UNSPECIFIED:
    }

    setMeasuredDimension(width, height);
}

private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                               int heightSpec, int[] measuredDimension) {
    View view = recycler.getViewForPosition(position);
    if (view != null) {
        RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
        int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                getPaddingLeft() + getPaddingRight(), p.width);
        int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                getPaddingTop() + getPaddingBottom(), p.height);
        view.measure(childWidthSpec, childHeightSpec);
        measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
        measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
        recycler.recycleView(view);
    }
}
}

Answer 1

您可以在supportv7中使用ItemTouchHelper，并实现simplecallback，如下所示：

        mSimpleCallback = new ItemTouchHelper.SimpleCallback(
            ItemTouchHelper.LEFT|ItemTouchHelper.RIGHT|ItemTouchHelper.UP|ItemTouchHelper.DOWN, 0) {
        @Override
        public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
            int fromPosition = viewHolder.getAdapterPosition();//得到拖动ViewHolder的position
            int toPosition = target.getAdapterPosition();//得到目标ViewHolder的position
            List<NHUser.DescriptionEntity> datas = mItemAdapter.getData();
            if (fromPosition < toPosition) {
                //分别把中间所有的item的位置重新交换
                for (int i = fromPosition; i < toPosition; i++) {
                    Collections.swap(datas, i, i + 1);
                }
            } else {
                for (int i = fromPosition; i > toPosition; i--) {
                    Collections.swap(datas, i, i - 1);
                }
            }
            mItemAdapter.notifyItemMoved(fromPosition, toPosition);
            return true;
        }

        @Override
        public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {

        }

    };

Recycler查看wrap_content与拖放

1 个答案: