关于android:Android-RecyclerView的使用

Android RecyclerView的应用

一:RecyclerView是什么
从Android5.0开始，谷歌推出一个用于大量数据展现的新控件RecyclerView,能够代替传统的ListView,更加弱小和灵便。
在AndroidX我的项目中增加依赖：implementation ‘androidx.recyclerview:recyclerview:1.1.0’
在非AndroidX我的项目中增加依赖：implementation ‘com.android.support:recyclerview-v7:26.1.0’//对应的是compileSdkVersion的版本

//Android布局应用
<android.support.v7.widget.RecyclerView
    android:layout_width="match_parent"
    android:layout_height="match_parent" />
    
    //AndroidX布局应用
    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

RecyclerView的长处
1.反对部分刷新
2.能够自定义Item增删时的动画
3.可能实现Item拖拽和侧滑删除等性能
二：RecyclerView应用

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/tv_recycler"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

1.创立布局管理器
LinearLayoutManager:线性布局，以垂直或程度滚动形式显示列表
GridLayoutManager:网格布局，在网格中显示我的项目
StaggeredGridLayoutManager：瀑布流布局，在扩散对齐网格中显示我的项目

LinearLayoutManager layoutManager=new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false);//线性布局管理器

  GridLayoutManager gridLayoutManager=new GridLayoutManager(this,3);//网格布局管理器
  
  StaggeredGridLayoutManager staggeredGridLayoutManager=new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL);//瀑布流布局

2.适配器应用

public class MyRecycleViewAdapter extends RecyclerView.Adapter<MyRecycleViewAdapter.MyHolder> {
    private List<String> mDatas;//数据源
    private Context context;
    
      private OnItemClickListener onItemClickListener;
    /**向内部提供调用设置监听*/
    public void setOnItemClickListener(OnItemClickListener onItemClickListener){
        this.onItemClickListener=onItemClickListener;
    }

    public MyRecycleViewAdapter(Context context,List<String> mDatas) {
        this.context=context;
        this.mDatas = mDatas;
    }

    /**
     * 创立ViewHolder并返回，后续item布局里控件都是从ViewHolder中取出
     */

    @NonNull
    @Override
    public MyHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        //将咱们自定义的item布局转成View
        View view = LayoutInflater.from(context).inflate(R.layout.item_one, parent, false);
        //将View传递给咱们自定义ViewHolder
        return new MyHolder(view);
    }
    /**通过办法提供的ViewHolder,将数据绑定到的ViewHolder中*/

    @Override
    public void onBindViewHolder(@NonNull MyHolder holder, int position) {
        holder.tv_content.setText(mDatas.get(position));
        
         holder.tv_content.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (onItemClickListener!=null){
                    onItemClickListener.onItemClick(v,holder.getAdapterPosition()+1);
                }
            }
        });


    }

    /**
     * 获取数据源总的条目
     */
    @Override
    public int getItemCount() {
        return mDatas.size();
    }

   static class MyHolder extends RecyclerView.ViewHolder {
        TextView tv_content;

        public MyHolder(@NonNull View itemView) {
            super(itemView);
            tv_content=itemView.findViewById(R.id.tv_content);
        }
    }
    
     /**自定义的接口*/
    public interface OnItemClickListener{
        void onItemClick(View view,int position);
    }
}

RecyclerView 封装了viewholder的回收复用，标准化了ViewHolder，编写Adapter面向的是ViewHolder而不是View,复用的逻辑封装了
创立适配器步骤：
1.创立Adapter：创立一个继承RecyclerView.Adapter<VH>的Adapter类（VH是ViewHolder的类名）
2.创立ViewHolder：在Adapter中创立一个继承RecyclerView.ViewHolder的动态外部类，记为VH。ViewHolder的实现和ListView的ViewHolder实现简直一样。
三个办法：
onCreateViewHolder：创立ViewHolder并返回，后续item布局里控件都是从ViewHolder中取出。
onBindViewHolder：通过办法提供的ViewHolder，将数据绑定到ViewHolder中。
getItemCount：获取数据源总的条数。
下面2个适配器和布局管理器是必须设置的

3.Item Decoration(可选)设置分割线

 //增加分割线
        tv_recycler.addItemDecoration(new DividerItemDecoration(this,DividerItemDecoration.VERTICAL));//默认的分割线

能够自定义距离款式须要继承RecyclerView.ItemDecoration类，该类是抽象类

public class MyItemDecoration extends RecyclerView.ItemDecoration {
    private final Drawable mLine;
    private final int orientation;
    public MyItemDecoration(Context context, int orientation) {
        this.orientation = orientation;
        int[] attrs = new int[]{android.R.attr.listDivider};//零碎的分割线色彩
        TypedArray a = context.obtainStyledAttributes(attrs);
        mLine = a.getDrawable(0);
        a.recycle();
    }

    /**在Item绘制之前被调用，用于绘制距离款式*/
    @Override
    public void onDraw(@NonNull Canvas c, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {
        super.onDraw(c, parent, state);
        if (orientation==RecyclerView.HORIZONTAL){
            drawVertical(c, parent, state);
        }else if (orientation==RecyclerView.VERTICAL){
            drawHorizontal(c, parent, state);
        }
    }
    /**onDraw和onDrawOver2个其中一个就行*/

    @Override
    public void onDrawOver(@NonNull Canvas c, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {
        super.onDrawOver(c, parent, state);
    }
    /**设置item的偏移量，偏移的局部用于填充距离款式，即设置分割线的宽、高；在RecyclerView的onMesure()中会调用该办法。*/

    @Override
    public void getItemOffsets(@NonNull Rect outRect, @NonNull View view, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        if (orientation == RecyclerView.HORIZONTAL) {
            //画垂直线
            outRect.set(0, 0, mLine.getIntrinsicWidth(), 0);
        } else if (orientation == RecyclerView.VERTICAL) {
            //画水平线
            outRect.set(0, 0, 0, mLine.getIntrinsicHeight());
        }
    }

    /**
     * 画垂直分割线
     */
    private void drawVertical(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);
            int left = child.getRight();
            int top = child.getTop();
            int right = left + mLine.getIntrinsicWidth();
            int bottom = child.getBottom();
            mLine.setBounds(left, top, right, bottom);
            mLine.draw(c);
        }
    }


    /**
     * 画程度分割线
     */
    private void drawHorizontal(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);
            int left = child.getLeft();
            int top = child.getBottom();
            int right = child.getRight();
            int bottom = top + mLine.getIntrinsicHeight();
            mLine.setBounds(left, top, right, bottom);
            mLine.draw(c);
        }
    }

}

咱们能够批改零碎自定义分割线色彩
在res下values下theme主题中
<!–自定义零碎分割线色彩–>
<item name=”android:listDivider”>@drawable/customizelistdivider </item>
在res/drawable中设置customizelistdivider

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient
        android:endColor="#ff0000ff"
        android:startColor="#ffff0000"
        android:type="linear" />
    <size android:height="4dp"
        android:width="4dp"/>
</shape>

应用设置自定义分割线
tv_recycler.addItemDecoration(new MyItemDecoration(this,RecyclerView.VERTICAL));

4.ItemAnimator动画（可选）
tv_recycler.setItemAnimator(new DefaultItemAnimator());//设置默认动画
默认动画继承DefaultItemAnimator来实现自定义动画

相干实现

public class SecondActivity extends AppCompatActivity {
    private RecyclerView tv_recycler;
    private MyRecycleViewAdapter myRecycleViewAdapter;
    private List<String> mDatas=new ArrayList<>();
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        initData();//初始化数据
        tv_recycler=findViewById(R.id.tv_recycler);
        //创立布局管理器
        LinearLayoutManager layoutManager=new LinearLayoutManager(this);//默认垂直排列
        //GridLayoutManager gridLayoutManager=new GridLayoutManager(this,3);
        //StaggeredGridLayoutManager staggeredGridLayoutManager=new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL);
        layoutManager.setOrientation(RecyclerView.HORIZONTAL);//设置程度排列
        //LinearLayoutManager layoutManager1=new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false);
        //设置布局管理器
        tv_recycler.setLayoutManager(layoutManager);
        //增加分割线
        tv_recycler.addItemDecoration(new MyItemDecoration(this,RecyclerView.VERTICAL));//自定义分割线
        tv_recycler.setItemAnimator(new DefaultItemAnimator());
        //tv_recycler.addItemDecoration(new DividerItemDecoration(this,DividerItemDecoration.VERTICAL));//默认的分割线
        //创立数据适配器
        myRecycleViewAdapter=new MyRecycleViewAdapter(this,mDatas);
        //设置数据适配器
        tv_recycler.setAdapter(myRecycleViewAdapter);
        //内部适配器数据监听条目点击
        myRecycleViewAdapter.setOnItemClickListener(new MyRecycleViewAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(View view, int position) {
                Toast.makeText(SecondActivity.this, "第"+position+"条数据", Toast.LENGTH_SHORT).show();
            }
        });
    }

    private void initData() {
        for (int i=0;i<40;i++){
            mDatas.add("我是item"+i);
        }
    }
}

5.Item条目监听，点击事件监听

  /**向内部提供调用设置监听*/
    public void setOnItemClickListener(OnItemClickListener onItemClickListener){
        this.onItemClickListener=onItemClickListener;
    }

    public MyRecycleViewAdapter(Context context,List<String> mDatas) {
        this.context=context;
        this.mDatas = mDatas;
    }

   /**自定义的接口*/
    public interface OnItemClickListener{
        void onItemClick(View view,int position);
    }
    
        @Override
    public void onBindViewHolder(@NonNull MyHolder holder, int position) {
        holder.tv_content.setText(mDatas.get(position));
        
         holder.tv_content.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (onItemClickListener!=null){
                    onItemClickListener.onItemClick(v,holder.getAdapterPosition()+1);//在绑定数据的时候给内部传递得postion从1开始
                }
            }
        });


    }
    
    //内部调用开始
    myRecycleViewAdapter.setOnItemClickListener(new MyRecycleViewAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(View view, int position) {
                Toast.makeText(SecondActivity.this, "第"+position+"条数据", Toast.LENGTH_SHORT).show();
            }
        });

END:只愿年过半百，归来仍是少年

关于android:Android-RecyclerView的使用

Android RecyclerView的应用

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关于android:Android-RecyclerView的使用

Android RecyclerView的应用

评论

发表回复 取消回复

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