Android AutoCompleteTextView使用

AutoCompleteTextView是一个android提供的可以补全输入的textview，效果类似于PC端百度一下那个输入框下面会带出来搜索历史。

先看下效果图：

我采用了自定义adapter的方式给他增加了删除的功能（单击x会删除那一条记录）
结合上SharedPerferences很容易就实现了输入历史记录提示功能。

实现步骤：
xml布局中添加AutoCompleteTextView

Activity中对其进行设置

		//我自定义的适配器下面有代码
        AutoAdapter adapter = new AutoAdapter(this,R.layout.rv_item_auto,list);
        //也可以使用系统自带的  
        //ArrayAdapter adapter = new ArrayAdapter(this,R.layout.support_simple_spinner_dropdown_item,list);
        acText.setAdapter(adapter);
        acText.setThreshold(1);//设置输入几个字符后开始出现提示 默认是2
        //我想在控件准备输入时直接弹出 所以设置了onFocusChange事件
        acText.setOnFocusChangeListener(new View.OnFocusChangeListener() {
            @Override
            public void onFocusChange(View v, boolean hasFocus) {
                if(hasFocus){//获取焦点时
                    acText.showDropDown();
                }
            }
        });

在写自定义适配器的时候一定要实现Filterable，要不然会失效。
其他地方和正常写Baseadapter是一样的

适配器的布局代码很简单 一个textview（显示提示内容）一个imageview（显示x）就不再贴代码了
AutoAdpater自定义适配器的代码

public class AutoAdapter extends BaseAdapter implements Filterable {

    Context mContext;
    List mList;
    List data;
    int mResource;


    public AutoAdapter(@NonNull Context context, int resource, List list) {
        mContext = context;
        mList = list;
        mResource = resource;
    }

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

    @Override
    public Object getItem(int position) {
        return mList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @NonNull
    @Override
    public View getView(final int position, @Nullable View convertView, @NonNull ViewGroup parent) {
        LayoutInflater inflater = LayoutInflater.from(mContext);
        View view = inflater.inflate(mResource,null);
        TextView tvAuto = view.findViewById(R.id.tv_auto);
        ImageView ivClose = view.findViewById(R.id.iv_delete);
        tvAuto.setText(mList.get(position));
        ivClose.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mList.remove(position);
                notifyDataSetChanged();
            }
        });
        return view;
    }

    @Override
    public Filter getFilter() {
        Filter filter = new Filter() {
            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                FilterResults results = new FilterResults();
                List list = new ArrayList<>();
                if(constraint != null){
                    for (String s:mList) {
                        list.add(s);
                    }
                }
                results.count = list.size();
                results.values = list;
                return results;
            }

            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {
                data = (List) results.values;
                notifyDataSetChanged();
            }
        };
        return filter;
    }
}