如何在 BaseAdapter 上实现 getFilter？答案

【问题标题】：How to implement getFilter on a BaseAdapter?如何在 BaseAdapter 上实现 getFilter？
【发布时间】：2012-07-22 02:56:05
【问题描述】：

我正在尝试在基本适配器上实现 getFilter() 以过滤掉列表上的搜索结果。有没有如何实现 getFilter() 的示例？

MainActivity.java

   final AppInfoAdapter adapter = new AppInfoAdapter(this, Utilities.getSystemFilteredApplication(this), getPackageManager());


        public void onTextChanged(CharSequence s, int start, int before,
                int count) {
           adapter.getFilter().filter(s); //Filter from my adapter
           adapter.notifyDataSetChanged(); //Update my view
        }

AppInfoAdapter.java

package com.example.permission;

import java.util.List;

import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.Filter;
import android.widget.Filterable;
import android.widget.ImageView;
import android.widget.TextView;

public class AppInfoAdapter extends BaseAdapter implements Filterable{
    private Context mContext;
    private List mListAppInfo;
    PackageManager mPackManager;

    public AppInfoAdapter(Context c, List list, PackageManager pm) {
        mContext = c;
        mListAppInfo = list;
        mPackManager = pm;
    }

    public int getCount() {
        return mListAppInfo.size();
    }


    public Object getItem(int position) {
        return mListAppInfo.get(position);
    }


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

    public View getView(int position, View convertView, ViewGroup parent) {
        // get the selected entry
        ApplicationInfo entry = (ApplicationInfo) mListAppInfo.get(position);

        // reference to convertView
        View v = convertView;

        // inflate new layout if null
        if(v == null) {
            LayoutInflater inflater = LayoutInflater.from(mContext);
            v = inflater.inflate(R.layout.layout_appinfo, null);
        }

        // load controls from layout resources
        ImageView ivAppIcon = (ImageView)v.findViewById(R.id.ivIcon);
        TextView tvAppName = (TextView)v.findViewById(R.id.tvName);
        TextView tvPkgName = (TextView)v.findViewById(R.id.tvPack);

        // set data to display
        ivAppIcon.setImageDrawable(entry.loadIcon(mPackManager));
        tvAppName.setText(entry.loadLabel(mPackManager));
        tvPkgName.setText(entry.packageName);

        // return view
        return v;
    }

    public Filter getFilter() {
        // TODO Auto-generated method stub
        return null;
    }


}

编辑：编辑代码并添加完整的 AppInfoAdapter.java

【问题讨论】：

标签： android listview filter baseadapter

【解决方案1】：

在你的适配器中放入这个类以在 getfilter 方法中使用它

//this is a simple class that filtering the ArrayList of strings used in adapter

public class filter_here extends Filter{

        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            // TODO Auto-generated method stub

            FilterResults Result = new FilterResults();
            // if constraint is empty return the original names
            if(constraint.length() == 0 ){
                Result.values = Original_Names;
                Result.count = Original_Names.size();
                return Result;
            }

            ArrayList<String> Filtered_Names = new ArrayList<String>();
            String filterString = constraint.toString().toLowerCase();
            String filterableString;

            for(int i = 0; i<Original_Names.size(); i++){
                filterableString = Original_Names.get(i);
                if(filterableString.toLowerCase().contains(filterString)){
                    Filtered_Names.add(filterableString);
                }
            }
            Result.values = Filtered_Names;
            Result.count = Filtered_Names.size();

            return Result;
        }

        @Override
        protected void publishResults(CharSequence constraint,FilterResults results) {
            // TODO Auto-generated method stub
            Names = (ArrayList<String>) results.values;
            notifyDataSetChanged();
        }

    }

在 getfilter 中从中返回实例

@Override
    public Filter getFilter() {
        // TODO Auto-generated method stub
        return filter;
    }

full example

【讨论】：

【解决方案2】：

这差点让我死了:)

像这样实现您的 BaseAdapter：

在您的公共适配器类中定义一个 List 的 ArrayList，它将包含原始列表的临时项目。

public class MyAdapter extends BaseAdapter implements Filterable{

    public static ArrayList<String> temporarylist;
    public static ArrayList<String> OriginalList;
    private Activity activity;

    public MyAdapter(Activity activity, ArrayList<String> OriginalList) {
         super();
         this.activity=activity;
         this.OriginalList = OriginalList;
         temporarylist=OriginalList;

    }
    .
    .
    .

用以下代码创建getFilter()方法[作为例子]：

public Filter getFilter() {
    Filter filter = new Filter() {

    @SuppressWarnings("unchecked")
    @Override
    protected void publishResults(CharSequence constraint, FilterResults results) {
        temporarylist=(ArrayList<String>)results.values;
        notifyDataSetChanged();
    }

    @Override
    protected FilterResults performFiltering(CharSequence constraint) {
        FilterResults results = new FilterResults();
        ArrayList<String> FilteredList= new ArrayList<String>();
        if (constraint == null || constraint.length() == 0) {
            // No filter implemented we return all the list
            results.values = OriginalList;
            results.count = OriginalList.size();
        }
        else {
            for (int i = 0; i < OriginalList.size(); i++) {
                String data = OriginalList.get(i);
                if (data.toLowerCase().contains(constraint.toString()))  {
                    FilteredList.add(data);
                }
            }
            results.values = FilteredList;
            results.count = FilteredList.size();
        }
        return results;
    }
};
return filter;
}

最后在您的 EditText 活动中：

MyAdapter adapter;
ArrayList<String> items;


ListView list = (ListView) findViewById(R.id.list);
items = new ArrayList<String>();
for (int i=0;i<30;i++){
     items.add("Hello world "+String.valueof(i));
}
adapter = new GameAdapter(this, items);
list.setAdapter(adapter);


EditText inputSearch = (EditText) findViewById(R.id.Search_txt);
     inputSearch.addTextChangedListener(new TextWatcher() {

            @Override
            public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
                // When user changed the Text
                MyActivity.this.adapter.getFilter().filter(cs);
            }

            @Override
            public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                    int arg3) {
                // TODO Auto-generated method stub

            }

            @Override
            public void afterTextChanged(Editable arg0) {
                // TODO Auto-generated method stub                          
            }
        });

【讨论】：

【解决方案3】：

你能发布你的完整AppInfoAdapter吗？还有任何理由从BaseAdapter 延伸而不是ArrayAdapter？如果你有ArrayList的对象，使用ArrayAdapter，它已经实现了Filterable接口。

实际上您使用的是List，您的适配器可以重写为扩展ArrayAdapter，它已经是Filterable。

public class AppInfoAdapter extends ArrayAdapter<ApplicationInfo> {

    private Context mContext;
    PackageManager mPackManager;

    public AppInfoAdapter(Context c, List<ApplicationInfo> list, PackageManager pm) {
        super(c, 0, new ArrayList<ApplicationInfo>());
        mContext = c;
        mPackManager = pm;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // get the selected entry
        ApplicationInfo entry = (ApplicationInfo) getItem(position);

        // reference to convertView
        View v = convertView;

        // inflate new layout if null
        if(v == null) {
            LayoutInflater inflater = LayoutInflater.from(mContext);
            v = inflater.inflate(R.layout.layout_appinfo, null);
        }

        // load controls from layout resources
        ImageView ivAppIcon = (ImageView)v.findViewById(R.id.ivIcon);
        TextView tvAppName = (TextView)v.findViewById(R.id.tvName);
        TextView tvPkgName = (TextView)v.findViewById(R.id.tvPack);

        // set data to display
        ivAppIcon.setImageDrawable(entry.loadIcon(mPackManager));
        tvAppName.setText(entry.loadLabel(mPackManager));
        tvPkgName.setText(entry.packageName);

        // return view
        return v;
    }
}

【讨论】：

我编辑了答案，所以你的适配器extends Filterable ArrayAdapter。
您的代码没有错误，但现在我看不到已安装应用程序的列表，只有 EditText
把super(c, 0, new ArrayList<ApplicationInfo>());换成super(c, 0, list);是我的错。
搜索部分工作，无法真正理解它是如何工作的，现在它有点错误，到目前为止它只适用于关键字'android'
查看ArrayAdapter 来源以了解ArrayFilter 的工作原理github.com/android/platform_frameworks_base/blob/master/core/… 或者这也可能有助于stackoverflow.com/a/4027085/1300995

【解决方案4】：

您需要返回一个Filter 的实例。要编写过滤器，请继承 Filter 并实现 performFiltering 和 publishResults。请参阅docs。

【讨论】：

【解决方案5】：

一般程序

在您的 ListView 上启用文本过滤
更改您的 baseadapter 以存储列表的两份副本，一份原件，一份过滤。
将 BaseAdapter 中的所有访问引用更改为引用过滤列表，而不是原始列表。
在 BaseAdapter 中实现您的过滤器功能。

第 1 步：
listview.setTextFilterEnabled(true);

第二步：

public class AppInfoAdapter extends BaseAdapter implements Filterable{
    private List mListAppInfo;
    private List mListAppInfoFiltered;

public AppInfoAdapter(Context c, List list, PackageManager pm) {
    mContext = c;
    mListAppInfo = list;
    mPackManager = pm;
    mPackManagerFiltered = pm; //added line
}

第三步：

public int getCount() {
    return mListAppInfoFiltered.size();
}
public Object getItem(int position) {
    return mListAppInfoFiltered.get(position);
}
public View getView(int position, View convertView, ViewGroup parent) {
    // get the selected entry
    ApplicationInfo entry = (ApplicationInfo) mListAppInfoFiltered.get(position);

}

第 4 步：我不确定你的列表是什么类型，所以假设一个字符串列表：

@Override
public Filter getFilter() {
    return new Filter() {
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            FilterResults results = new FilterResults();
            if (constraint == null || constraint.length() == 0) {
                //no search, so just return all the data
                results.count = mListAppInfo.size();
                results.values = mListAppInfo;
            } else {//do the search
                List<String> resultsData = new ArrayList<>();
                String searchStr = constraint.toString().toUpperCase();
                for (String s : mListAppInfo)
                        if (s.toUpperCase().contains(searchStr)) resultsData.add(s);
                    results.count = resultsData.size();
                    results.values = resultsData;
                }
                return results;
            }

            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {
                mListAppInfoFiltered = (ArrayList<MyObject>) results.values;
                notifyDataSetChanged();
            }
        };
    }
}

【讨论】：

【解决方案6】：

getFilter() 可以在适配器中被覆盖并返回包含过滤列表的过滤器对象。 Filter() 类中有两个关键方法； performFiltering 和 publishResults。第一种方法在工作线程中执行过滤，后一种方法返回过滤后的对象列表。

您可以参考下面的示例代码

@Override
public Filter getFilter() {

        return new Filter() {

            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {
                // TODO Auto-generated method stub
                if (results.count == 0) {
                    notifyDataSetInvalidated();
                }else{
                    mListAppInfo = (ArrayList<SampleItem>) results.values;
                    notifyDataSetChanged();
                }
            }

            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                // TODO Auto-generated method stub
                FilterResults results = new FilterResults();

                if (constraint == null || constraint.length() == 0) {
                    results.values = mListAppInfo;
                    results.count = mListAppInfo.size();
                }else{
                    ArrayList<SampleItem> filter_items = new ArrayList<>(); 
                    for (SampleItem item : mListAppInfo) {
                        if (item.getItemName().toLowerCase().startsWith(constraint.toString().toLowerCase())) {
                            filter_items.add(item);
                        }
                    }
                    results.values =  filter_items ;
                    results.count = filter_items.size();
                }
                return results;
            }
        };
    }

希望你觉得它有用。

【讨论】：

【解决方案7】：

使用 ArrayAdapter 扩展您的类，然后覆盖方法，并创建过滤器类的对象并返回。

【讨论】：