安卓recyclerview的基本使用

Posted 2020-10-20 layfork

1.先在布局文件中写

 <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_view"
        android:scrollbars="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

2.mainactivity

public class MainActivity extends AppCompatActivity {
    private RecyclerView mRecyclerView;
    private ArrayList<String> mDatas=new ArrayList<>();
    private MyAdapter myAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRecyclerView = findViewById(R.id.my_recycler_view);
        initDatas();
        myAdapter =new MyAdapter(mDatas);
        mRecyclerView.setAdapter(myAdapter);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        //mRecyclerView.setLayoutManager(new GridLayoutManager(this,4));
       // mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(4,StaggeredGridLayoutManager.HORIZONTAL));
        //配置分割线
        mRecyclerView.addItemDecoration(new DividerItemDecoration(this,DividerItemDecoration.VERTICAL_LIST));
        //事件监听

        myAdapter.setOnItemClickListener(new MyAdapter.OnItemClickListener() {
            @Override
            public void onClick(View v, int position, String city) {
                Toast.makeText(MainActivity.this,city,Toast.LENGTH_SHORT).show();
            }
        });

        int size =mDatas.size();
        //添加数据到头部
        myAdapter.addData(size,"adddddddddd");

        //删除数据
        myAdapter.removeData(0);
    }

    private static final String TAG = "MainActivity";
    private void initDatas(){
        mDatas.add("aa");
        mDatas.add("cv");
        mDatas.add("cv1");
        mDatas.add("cv112");
        mDatas.add("cv112");
        mDatas.add("cv112");
        mDatas.add("cv112");
        mDatas.add("cv112");
        mDatas.add("cv112");
        mDatas.add("cv112");
        mDatas.add("cv112");
        mDatas.add("cv112");
        mDatas.add("cv112");
        mDatas.add("cv112");
    }


}

3.adpter

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
    private static List<String> mData;
    private static OnItemClickListener mListener;
    public void setOnItemClickListener (OnItemClickListener listener){
        mListener=listener;
    }


    public MyAdapter(List<String> data) {
        mData = data;
    }



    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        // 实例化展示的view
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.view_rv_item, parent, false);
        // 实例化viewholder
        ViewHolder viewHolder = new ViewHolder(v);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        // 绑定数据
        holder.mTv.setText(mData.get(position));
    }

    @Override
    public int getItemCount() {
        return mData == null ? 0 : mData.size();
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {

        TextView mTv;

        public ViewHolder(View itemView) {
            super(itemView);
            mTv = (TextView) itemView.findViewById(R.id.item_tv);

            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    if(mListener!=null){
                        mListener.onClick(view,getLayoutPosition(),mData.get(getLayoutPosition()));
                    }
                }
            });
        }
    }


    interface OnItemClickListener{
        void onClick(View v,int position,String city);

    }


    /*
    *  @param 添加的位置
    *  @param 添加的数据
    * */
    public void addData(int position,String city){
        mData.add(position,city);
        notifyItemInserted(position);
    }


    public void removeData(int position){
        mData.remove(position);
        notifyItemRemoved(position);
    }
}

单独创建item的布局，view_rv_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="45dp">

    <TextView
        android:id="@+id/item_tv"
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        />
</LinearLayout>

item的下划线，要自己写一个类，有点麻烦，直接抄了网上

public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    private static final int[] ATTRS = new int[]{
            android.R.attr.listDivider
    };

    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;

    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;

    private Drawable mDivider;

    private int mOrientation;

    public DividerItemDecoration(Context context, int orientation) {
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        a.recycle();
        setOrientation(orientation);
    }

    public void setOrientation(int orientation) {
        if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
            throw new IllegalArgumentException("invalid orientation");
        }
        mOrientation = orientation;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent) {
//        Log.v("recyclerview - itemdecoration", "onDraw()");

        if (mOrientation == VERTICAL_LIST) {
            drawVertical(c, parent);
        } else {
            drawHorizontal(c, parent);
        }

    }

    public void drawVertical(Canvas c, RecyclerView parent) {
        final int left = parent.getPaddingLeft();
        final int right = parent.getWidth() - parent.getPaddingRight();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            android.support.v7.widget.RecyclerView v = new android.support.v7.widget.RecyclerView(parent.getContext());
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int top = child.getBottom() + params.bottomMargin;
            final int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    public void drawHorizontal(Canvas c, RecyclerView parent) {
        final int top = parent.getPaddingTop();
        final int bottom = parent.getHeight() - parent.getPaddingBottom();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int left = child.getRight() + params.rightMargin;
            final int right = left + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
        if (mOrientation == VERTICAL_LIST) {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        }
    }
}

对了，使用之前要配置先的

   api ‘com.android.support:recyclerview-v7:26.1.0‘

 

这里写了展示和点击事件,比较简单，