RecyclerView基础

单纯的笔记,需深入请研究其他大神的博客,谢谢!

效果:

1.引入 依赖:  compile 'com.android.support:recyclerview-v7:25.3.1'

2.activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.demo.demo10.MainActivity">

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

    </android.support.v7.widget.RecyclerView>

</RelativeLayout>

3.每条item布局(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="50dp">

    <TextView
        android:id="@+id/temp_item"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:gravity="center"
        android:text="temp"/>

</LinearLayout>

4.基本分割线(DividerItemDecoration.java):

public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;
    private Drawable mDivider;
    private int mOrientation;
    private static final int[] ATTRS = new int[]{
            android.R.attr.listDivider
    };

    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) {

        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);
        }
    }
}

5.MyAdapter.java:

class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
    private Context mContext;
    private List<String> mDatas;

    public MyAdapter(Context context) {
        this.mContext = context;
        mDatas = new ArrayList<>();
        initData();
    }

    private void initData() {
        for (int i = 'a'; i <= 'z'; i++) {
            mDatas.add((char) i + "");
        }
    }

    /**
     * 点击和长按监听
     */
    public interface OnItemClickListener {
        void onItemClick(View view, int position);

        void onItemLongClick(View view, int position);
    }

    private OnItemClickListener mOnItemClickListener;

    public void setOnItemClickListener(OnItemClickListener listener) {
        this.mOnItemClickListener = listener;
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        MyViewHolder holder = new MyViewHolder(LayoutInflater.from(mContext).inflate(R.layout.item, parent, false));
        return holder;
    }

    @Override
    public void onBindViewHolder(final MyViewHolder holder, final int position) {
        String str = mDatas.get(position);
        holder.textView.setText(str);
        //自定义点击事件和长按事件
        if (mOnItemClickListener != null) {
            holder.itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    int layoutPosition = holder.getLayoutPosition();//避免添加item时不刷新item索引
                    mOnItemClickListener.onItemClick(holder.itemView, layoutPosition);
                }
            });
            holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                    int layoutPosition = holder.getLayoutPosition();//避免添加item时不刷新item索引
                    mOnItemClickListener.onItemLongClick(holder.itemView, layoutPosition);
                    return true;
                }
            });
        }
    }

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

    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView textView;

        public MyViewHolder(View itemView) {
            super(itemView);
            textView = (TextView) itemView.findViewById(R.id.temp_item);
        }
    }

    /**
     * 添加 item
     */
    public void addItem(int position) {
        mDatas.add(position, "添加了数据");
        notifyItemInserted(position);//切记不要写成notifyDataSetChanged()
    }

    /**
     * 删除item
     */
    public void removeItem(int position) {
        mDatas.remove(position);
        Toast.makeText(mContext, "删除成功", Toast.LENGTH_SHORT).show();
        notifyItemRemoved(position);//切记不要写成notifyDataSetChanged()
    }
}

6.MainActivity.java:

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private MyAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerview);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        adapter = new MyAdapter(this);
        mRecyclerView.setAdapter(adapter);
        mRecyclerView.setItemAnimator(new DefaultItemAnimator());//设置自动增删动画
        mRecyclerView.addItemDecoration(new DividerItemDecoration(this, LinearLayoutManager.VERTICAL));
        adapter.setOnItemClickListener(new MyAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(View view, int position) {
                Toast.makeText(MainActivity.this, "单击了第" + (position + 1) + "条item", Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onItemLongClick(View view, int position) {
                adapter.removeItem(position);//长按删除
            }
        });
    }
}

项目中根据实际需求更改分割线和每个item样式.