RecyclerView學習筆記整理（4）item的點選添加和删除

我們來學習一下item的點選添加和删除

源代碼可以上這裡擷取Github：https://github.com/307572384/recycleitemnew

我們先來看一下如何新增item和删除

首先我們需要在Adapter中新增這一段代碼

/**
	 * 添加新的Item
	 */
	public void addNewItem() {
		if (mData == null) {
			mData = new ArrayList<>();
		}
		mData.add(0, "new item");
		notifyItemInserted(0);
	}

	//删除item
	public void deleteItem() {
		if (mData == null || mData.isEmpty()) {
			return;
		}
		mData.remove(0);
		notifyItemRemoved(0);
	}

然後我們再看看activity裡面需要做些什麼

我們先在布局管理器下面設定一下添加和移除的動畫

//設定item添加和移除的動畫
		mRecyclerView.setItemAnimator(new DefaultItemAnimator());

然後再給添加和删除的item的那個按鈕新增一個點選事件

這裡新增點選事件以後後面你可以根據自己想要的進行修改

@Override
	public void onClick(View v) {
		int id = v.getId();
		if (id == R.id.rv_add_item_btn) {
			mAdapter.addNewItem();
			mLayoutManager.scrollToPosition(0);
		} else if (id == R.id.rv_del_item_btn) {
			mAdapter.deleteItem();
			mLayoutManager.scrollToPosition(0);
		}
	}

然後我給主的Recyclerview做分支的item跳轉到其他的activity也是recyclerview布局的時候發現

Adapter需要放在oncreate裡面，我寫了initview放在裡面好像無法調用和識别到。

@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_rv_linear);
		initView();
		initData();
		initAction();
		mRecyclerView.setAdapter(mAdapter);//設定adapter
	}

我們來看看完整的代碼

DLActivity

**
 * 添加和删除item的Recyclerdemo
 */

public class DLActivity extends MDBaseActivity implements View.OnClickListener {
	private TextView                   mTextViewadd;
	private TextView                   mTextViewdel;
	private RecyclerView               mRecyclerView;
	private MDRvAdapter                mAdapter;
	private RecyclerView.LayoutManager mLayoutManager;


	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_rv_linear);
		initView();
		initData();
		initAction();
		mRecyclerView.setAdapter(mAdapter);//設定adpter
	}

	private void initAction() {
		mTextViewadd.setOnClickListener(this);
		mTextViewdel.setOnClickListener(this);
	}

	private void initData() {

		mAdapter = new MDRvAdapter(getData());
		mAdapter.setOnItemClickListener(new MDRvAdapter.OnItemClickListener() {
			@Override
			public void onItemClick(View view, int position) {
				Toast.makeText(DLActivity.this, "click " + position + " item", Toast.LENGTH_SHORT).show();//單點選事件
			}

			@Override
			public void onItemLongClick(View view, int position) {
				Toast.makeText(DLActivity.this, "long click " + position + " item", Toast.LENGTH_SHORT).show();//長按點選事件
			}
		});
	}

	private void initView() {
		mTextViewadd = (TextView) findViewById(R.id.rv_add_item_btn);
		mTextViewdel = (TextView) findViewById(R.id.rv_del_item_btn);
		mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
		mLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
		//設定布局管理器
		mRecyclerView.setLayoutManager(mLayoutManager);


		//設定item添加和移除的動畫
		mRecyclerView.setItemAnimator(new DefaultItemAnimator());
		// 設定Item之間間隔樣式
		mRecyclerView.addItemDecoration(new MDLinearRvDividerDecoration(this, LinearLayoutManager.VERTICAL));
	}

	@Override
	public void onClick(View v) {
		int id = v.getId();
		if (id == R.id.rv_add_item_btn) {
			mAdapter.addNewItem();
			mLayoutManager.scrollToPosition(0);
		} else if (id == R.id.rv_del_item_btn) {
			mAdapter.deleteItem();
			mLayoutManager.scrollToPosition(0);
		}
	}

	private ArrayList<String> getData() {
		ArrayList<String> data = new ArrayList<>();
		String temp = " item";
		for (int i = 0; i < 20; i++) {
			data.add(i + temp);
		}

		return data;
	}

}

MDRvAdapter

public class MDRvAdapter extends RecyclerView.Adapter<MDRvAdapter.ViewHolder> {
    	//展示資料
    	private ArrayList<String>               mData;
    	//事件回調監聽
    	private MDRvAdapter.OnItemClickListener onItemClickListener;
    
    	public MDRvAdapter(ArrayList<String> data) {
    		this.mData = data;
    	}
    
    	public void updateData(ArrayList<String> data) {
    		this.mData = data;
    		notifyDataSetChanged();
    	}
    
    	/**
    	 * 添加新的Item
    	 */
    	public void addNewItem() {
    		if (mData == null) {
    			mData = new ArrayList<>();
    		}
    		mData.add(0, "new item");
    		notifyItemInserted(0);
    	}
    
    	//删除item
    	public void deleteItem() {
    		if (mData == null || mData.isEmpty()) {
    			return;
    		}
    		mData.remove(0);
    		notifyItemRemoved(0);
    	}
    
    	/**
    	 * 設定回調監聽
    	 *
    	 * @param listener
    	 */
    	public void setOnItemClickListener(MDRvAdapter.OnItemClickListener listener) {
    		this.onItemClickListener = listener;
    	}
    
    	@Override
    	public MDRvAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    		// 執行個體化展示的view
    		View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.view_rv_item, parent, false);
    		// 執行個體化viewholder
    		ViewHolder viewHolder = new ViewHolder(v);
    		return viewHolder;
    	}
    
    	@Override
    	public void onBindViewHolder(final MDRvAdapter.ViewHolder holder, int position) {
    		//綁定資料
    		holder.mTv.setText(mData.get(position));
    		holder.itemView.setOnClickListener(new View.OnClickListener() {
    			@Override
    			public void onClick(View v) {
    				if (onItemClickListener != null) {
    					int pos = holder.getLayoutPosition();
    					onItemClickListener.onItemClick(holder.itemView, pos);
    				}
    			}
    		});
    		holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
    			@Override
    			public boolean onLongClick(View v) {
    				if (onItemClickListener != null) {
    					int pos = holder.getLayoutPosition();
    					onItemClickListener.onItemLongClick(holder.itemView, pos);
    				}
    				return true;
    			}
    
    
    		});
    	}
    
    	@Override
    	public int getItemCount() {
    		return mData.size();
    	}
    
    	public interface OnItemClickListener {
    		void onItemClick(View view, int position);
    
    		void onItemLongClick(View view, int position);
    	}
    
    	public static class ViewHolder extends RecyclerView.ViewHolder {
    
    		TextView mTv;
    
    		public ViewHolder(View itemView) {
    			super(itemView);
    			mTv = (TextView) itemView.findViewById(R.id.item_tv1);
    		}
    	}
    }

MDLinearRvDividerDecoration

這個是分隔線

public class MDLinearRvDividerDecoration extends RecyclerView.ItemDecoration {

	public static final  int   HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
	public static final  int   VERTICAL_LIST   = LinearLayoutManager.VERTICAL;
	private static final int[] ATTRS           = new int[]{
			android.R.attr.listDivider
	};
	/**
	 * 用于繪制間隔樣式
	 */
	private Drawable mDivider;
	/**
	 * 清單的方向，水準/豎直
	 */
	private int      mOrientation;


	public MDLinearRvDividerDecoration(Context context, int orientation) {
		// 擷取預設主題的屬性
		final TypedArray a = context.obtainStyledAttributes(ATTRS);
		mDivider = a.getDrawable(0);
		a.recycle();
		setOrientation(orientation);
	}

	@Override
	public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
		// 繪制間隔
		if (mOrientation == VERTICAL_LIST) {
			drawVertical(c, parent);
		} else {
			drawHorizontal(c, parent);
		}
	}

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

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

	/**
	 * 繪制間隔
	 */
	private void drawVertical(Canvas c, RecyclerView parent) {
		final int left = parent.getPaddingLeft();
		final int right = parent.getWidth() - parent.getPaddingRight();
		final int childCount = parent.getChildCount();
		// 周遊
		for (int i = 0; i < childCount; i++) {
			final View child = parent.getChildAt(i);
			final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
					.getLayoutParams();
			final int top = child.getBottom() + params.bottomMargin +
					Math.round(ViewCompat.getTranslationY(child));
			final int bottom = top + mDivider.getIntrinsicHeight();
			mDivider.setBounds(left, top, right, bottom);
			mDivider.draw(c);
		}
	}

	/**
	 * 繪制間隔
	 */
	private 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 +
					Math.round(ViewCompat.getTranslationX(child));
			final int right = left + mDivider.getIntrinsicHeight();
			mDivider.setBounds(left, top, right, bottom);
			mDivider.draw(c);
		}
	}
}

下面是layout布局

activity_rv_linear

<?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="match_parent"
    android:orientation="vertical">
    <TextView
        android:id="@+id/rv_add_item_btn"
        android:layout_width="match_parent"
        android:layout_height="@dimen/md_common_btn_height"
        android:gravity="center"
        android:text="@string/md_add_item"/>
    <TextView
        android:id="@+id/rv_del_item_btn"
        android:layout_width="match_parent"
        android:layout_height="@dimen/md_common_btn_height"
        android:background="@android:color/darker_gray"
        android:gravity="center"
        android:text="@string/md_del_item"/>

    <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:fadeScrollbars="true" />
</LinearLayout>

view_rv_item

<?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="match_parent">
<TextView
    android:id="@+id/item_tv1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="center"
    android:text="item"/>
</LinearLayout>

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