Android RecyclerView 设置item间隔的方法

Posted 2020-10-04 星辰

RecyclerView大家常用，但是如何给加载出来的item增加间隔很多人都不知道，下面是方法，直接上代码了：

LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(layoutManager);
qujangAdapter = new QujiangAdapter(qujiangList, getActivity());
//设置item间距，30dp
recyclerView.addItemDecoration(new SpaceItemDecoration(30));
recyclerView.setAdapter(qujangAdapter);

上面的代码是用一个LinearLayoutManager 加载RecyclerView，和一般加载代码不一样的是多了  recyclerView.addItemDecoration(new SpaceItemDecoration(30)); 这一行代码。

 下面是SpaceItemDecoration类的实现：

class SpaceItemDecoration extends RecyclerView.ItemDecoration {
    int mSpace;
 
    /**
     * Retrieve any offsets for the given item. Each field of <code>outRect</code> specifies
     * the number of pixels that the item view should be inset by, similar to padding or margin.
     * The default implementation sets the bounds of outRect to 0 and returns.
     * <p>
     * <p>
     * If this ItemDecoration does not affect the positioning of item views, it should set
     * all four fields of <code>outRect</code> (left, top, right, bottom) to zero
     * before returning.
     * <p>
     * <p>
     * If you need to access Adapter for additional data, you can call
     * {@link RecyclerView#getChildAdapterPosition(View)} to get the adapter position of the
     * View.
     *
     * @param outRect Rect to receive the output.
     * @param view    The child view to decorate
     * @param parent  RecyclerView this ItemDecoration is decorating
     * @param state   The current state of RecyclerView.
     */
    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        outRect.left = mSpace;
        outRect.right = mSpace;
        outRect.bottom = mSpace;
        if (parent.getChildAdapterPosition(view) == 0) {
            outRect.top = mSpace;
        }
 
    }
 
    public SpaceItemDecoration(int space) {
        this.mSpace = space;
    }
}

　在该类的getItemOffsets方法中设置item各个方向的间距。这里面加入了如果是RecyclerView的第一个子项，则设置该子项上方的间距。

     运行出来之后就会发现每个item四周都有间距了。