RecyclerView网格布局

最新推荐文章于 2024-08-12 20:12:46 发布

原创最新推荐文章于 2024-08-12 20:12:46 发布 · 3.4k 阅读

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本文主要介绍了如何在Android中利用RecyclerView的GridLayoutManager来创建网格布局，以解决线性布局扩展性不足的问题。通过定义itemType并填充不同布局，实现动态适配各行的item，从而达到更好的扩展性。

GridLayoutManager

一、引入问题

在这里插入图片描述

要实现这个布局，我们需要怎么做呢？

用线性布局画各种长度尺寸的button?
可行，但扩展性不够，假如将第二行和第三行互换位置呢再增加几行呢再增加几种类型的item呢？
我们可以试下recyclerview的网格布局，进行动态适配各行的item
可行，扩展性够

二、解决问题

方案：使用recyclerview的网格布局

定义itemType，针对不同的类型填充不同的布局

这里我们用不同itemType，之后可以在任意位置扩展这些类型的item

核心代码

public class MainActivity extends AppCompatActivity {
    private RecyclerView mRecyclerView;
    private RecyAdapter mAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRecyclerView = findViewById(R.id.recycler_view);
        init();
    }

    public void init() {
        GridLayoutManager gridLayoutManager = new GridLayoutManager(getApplicationContext(), 3);
        mRecyclerView.setLayoutManager(gridLayoutManager);
        mAdapter = new RecyAdapter();
        mRecyclerView.setAdapter(mAdapter);
        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                int itemViewType = mAdapter.getItemViewType(position);
                switch (itemViewType) {
                    case Constant.THREE_COLUME_ITEM_TYPE:
                        return 3;
                    case Constant.TWO_COLUME_ITEM_TYPE:
                        return 2;
                    default:
                        return 1;
                }
            }
        });
        mRecyclerView.addItemDecoration(new RecyclerView.ItemDecoration() {
            @Override
            public void getItemOffsets(@NonNull Rect outRect, @NonNull View view, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {
                super.getItemOffsets(outRect, view, parent, state);
                outRect.bottom = 30;
                outRect.left = 30;
            }
        });
    }
}

public class RecyAdapter extends RecyclerView.Adapter {
    private List<Integer> mData = new ArrayList<>();

    public RecyAdapter() {
        mData.add(0);
        mData.add(1);
        mData.add(2);
        mData.add(3);
        mData.add(4);
        mData.add(5);
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view;
        int layoutId;
        switch (viewType) {
            case Constant.THREE_COLUME_ITEM_TYPE:
                layoutId = R.layout.item_three_view_layout;
                break;
            case Constant.TWO_COLUME_ITEM_TYPE:
                layoutId = R.layout.item_two_view_layout;
                break;
            default:
                layoutId = R.layout.item_view_layout;
                break;
        }
        view = LayoutInflater.from(parent.getContext()).inflate(layoutId, parent, false);
        return new VH(view);
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
        VH vh = (VH) holder;
        vh.mText.setText(mData.get(position) + "");
    }

    @Override
    public int getItemCount() {
        return mData.size();
    }

    @Override
    public int getItemViewType(int position) {
        switch (position) {
            case 0:
                return Constant.THREE_COLUME_ITEM_TYPE;
            case 5:
                return Constant.TWO_COLUME_ITEM_TYPE;
            default:
                return Constant.ONE_COLUME_ITEM_TYPE;
        }
    }

    class VH extends RecyclerView.ViewHolder {
        TextView mText;

        public VH(@NonNull View itemView) {
            super(itemView);
            mText = itemView.findViewById(R.id.text);
        }
    }
}

public class Constant {
    public static final int THREE_COLUME_ITEM_TYPE = 0;
    public static final int ONE_COLUME_ITEM_TYPE = 1;
    public static final int TWO_COLUME_ITEM_TYPE = 2;
}