android recyclerview 只有第一条和最后一条样式不一样,怎么处理
时间: 2024-02-27 18:56:39 浏览: 18
你可以通过为RecyclerView添加一个装饰器(Decorator)来实现第一条和最后一条显示不同的样式。
具体步骤如下:
1. 定义一个类,继承自RecyclerView.ItemDecoration。
2. 在该类中,重写getItemOffsets()方法,通过position参数判断当前处理的是第一条或最后一条数据,然后为其添加对应的偏移量。
3. 在该类中,重写onDraw()方法,通过position参数判断当前处理的是第一条或最后一条数据,然后绘制对应的样式。
示例代码如下:
```java
public class MyItemDecoration extends RecyclerView.ItemDecoration {
private int mFirstItemOffset;
private int mLastItemOffset;
private Drawable mFirstItemDecoration;
private Drawable mLastItemDecoration;
public MyItemDecoration(int firstItemOffset, int lastItemOffset,
Drawable firstItemDecoration, Drawable lastItemDecoration) {
mFirstItemOffset = firstItemOffset;
mLastItemOffset = lastItemOffset;
mFirstItemDecoration = firstItemDecoration;
mLastItemDecoration = lastItemDecoration;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
int position = parent.getChildAdapterPosition(view);
if (position == 0) {
outRect.top = mFirstItemOffset;
} else if (position == parent.getAdapter().getItemCount() - 1) {
outRect.bottom = mLastItemOffset;
} else {
outRect.setEmpty();
}
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
super.onDraw(c, parent, state);
int childCount = parent.getChildCount();
int itemCount = parent.getAdapter().getItemCount();
for (int i = 0; i < childCount; i++) {
View child = parent.getChildAt(i);
int position = parent.getChildAdapterPosition(child);
if (position == 0 && mFirstItemDecoration != null) {
mFirstItemDecoration.setBounds(
parent.getPaddingLeft(),
parent.getPaddingTop(),
parent.getWidth() - parent.getPaddingRight(),
child.getTop());
mFirstItemDecoration.draw(c);
} else if (position == itemCount - 1 && mLastItemDecoration != null) {
mLastItemDecoration.setBounds(
parent.getPaddingLeft(),
child.getBottom(),
parent.getWidth() - parent.getPaddingRight(),
parent.getHeight() - parent.getPaddingBottom());
mLastItemDecoration.draw(c);
}
}
}
}
```
在使用RecyclerView时,通过以下方式为其添加上述装饰器:
```java
recyclerView.addItemDecoration(new MyItemDecoration(
getResources().getDimensionPixelSize(R.dimen.first_item_offset),
getResources().getDimensionPixelSize(R.dimen.last_item_offset),
getResources().getDrawable(R.drawable.first_item_decoration),
getResources().getDrawable(R.drawable.last_item_decoration)));
```
其中,R.dimen.first_item_offset和R.dimen.last_item_offset是分别定义第一条和最后一条数据的偏移量,R.drawable.first_item_decoration和R.drawable.last_item_decoration是分别定义第一条和最后一条数据的样式。