Android 小技巧之 RecyclerView

1. 导入 v7 包

implementation 'com.android.support:recyclerview-v7:28.0.0'

2. 使用 RecyclerView

MainActivity.java

public class MainActivity extends AppCompatActivity {
    private RecyclerView mRecyclerView;
    private List<String> mList = new ArrayList<>();
    private HomeAdapter mAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initData();
        mRecyclerView = findViewById(R.id.recycler_view);
        LinearLayoutManager manager = new LinearLayoutManager(this);
        manager.setOrientation(LinearLayoutManager.VERTICAL);
        mRecyclerView.setLayoutManager(manager);
        mRecyclerView.setAdapter(mAdapter);

        mAdapter.setOnItemClickListener(new HomeAdapter.OnItemClickListener() {
            @Override
            public void onClick(int position) {
                Toast.makeText(MainActivity.this,"点击了"+position,Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onLongClick(final int position) {
                new AlertDialog.Builder(MainActivity.this)
                        .setTitle("确认删除嘛")
                        .setNegativeButton("取消",null)
                        .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialogInterface, int i) {
                                mAdapter.removeData(position);
                            }
                        })
                        .show();
            }
        });
    }

    private void initData() {
        for (int index = 0;index < 10;index++){
            mList.add("android");
        }
        mAdapter = new HomeAdapter();
        mAdapter.setData(mList);
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

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

</android.support.constraint.ConstraintLayout>

3. 适配器

item_recycler.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="5dp">
    <ImageView
        android:id="@+id/iv_icon"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:src="@drawable/ic_logo"
        android:layout_gravity="center_vertical"/>

    <TextView
        android:id="@+id/tv_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="android"
        android:textSize="18sp"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="10dp"/>
</LinearLayout>

HomeAdapter.java

/**
 * Created on 2019/6/13 11:45 AM
 *
 * @author Scarf Gong
 */
public class HomeAdapter extends RecyclerView.Adapter<HomeAdapter.ViewHolder> {
    private List<String> mList = new ArrayList<>();

    static class ViewHolder extends RecyclerView.ViewHolder {
        ImageView fruitImage;
        TextView fruitName;
        public ViewHolder(View itemView) {
            super(itemView);
            fruitImage = itemView.findViewById(R.id.iv_icon);
            fruitName = itemView.findViewById(R.id.tv_title);
        }
    }

    public void setData(List<String> list) {
        this.mList.clear();
        this.mList.addAll(list);
        notifyDataSetChanged();
    }

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

    public void addData(int position) {
        mList.add(position,"ios");
        notifyItemInserted(position);
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int position) {
        return new ViewHolder(LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item_recycler, parent, false));
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, final int position) {
        if (position % 2 == 0) {
            holder.itemView.setBackgroundColor(Color.parseColor("#191977d3"));
        } else {
            holder.itemView.setBackgroundColor(Color.parseColor("#fafafa"));
        }

        if (mOnItemClickListener != null) {
            holder.fruitImage.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    mOnItemClickListener.onClick(position);
                }
            });

            holder.fruitImage.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                    mOnItemClickListener.onLongClick(position);
                    return true;
                }
            });
        }


    }

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

    public interface OnItemClickListener {
        void onClick(int position);
        void onLongClick(int position);
    }

    private OnItemClickListener mOnItemClickListener;

    public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
        mOnItemClickListener = onItemClickListener;
    }

}

4. 设置分割线

用 mRecyclerView.addItemDecoration() 来加入分割线，谷歌没有提供默认的分割线需要我们继承 RecyclerView.ItemDecoration 来自定义分割线：

/**
 * Created on 2019/6/13 1:50 PM
 *
 * @author Scarf Gong
 */
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) {
        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. 效果图

rv.jpg