Android SearchView过滤空白字符与高效数据流处理教程

@Override
protected FilterResults performFiltering(CharSequence constraint) {
    FilterResults results = new FilterResults();
    List<String> filteredList = new ArrayList<>();

    // 关键步骤：去除输入约束的首尾空白，并转换为小写进行不敏感匹配
    String filterPattern = constraint.toString().toLowerCase().trim();

    if (filterPattern.isEmpty()) {
        // 如果过滤模式为空（包括只输入了空白字符），则显示所有原始数据
        filteredList.addAll(originalDataList);
    } else {
        // ... 继续执行过滤逻辑
    }

    results.values = filteredList;
    results.count = filteredList.size();
    return results;
}

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

// 假设这是您的自定义数据模型
class MyItem {
    String name;
    // ... 其他属性

    public MyItem(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    @Override
    public String toString() {
        return name;
    }
}

public class MyFilterableAdapter extends BaseAdapter implements Filterable {

    private List<MyItem> originalDataList; // 原始完整数据
    private List<MyItem> currentDataList;  // 当前显示的数据

    public MyFilterableAdapter(List<MyItem> data) {
        this.originalDataList = new ArrayList<>(data); // 存储原始数据的副本
        this.currentDataList = new ArrayList<>(data);
    }

    // ... BaseAdapter 的其他方法，如getCount(), getItem(), getItemId(), getView()

    @Override
    public Filter getFilter() {
        return new ItemFilter();
    }

    private class ItemFilter extends Filter {
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            FilterResults results = new FilterResults();
            List<MyItem> filteredList = new ArrayList<>();

            // 预处理输入约束：去除首尾空白并转换为小写
            String filterPattern = constraint.toString().toLowerCase().trim();

            if (filterPattern.isEmpty()) {
                // 如果过滤模式为空，显示所有原始数据
                filteredList.addAll(originalDataList);
            } else {
                // 使用Java Stream API进行高效过滤
                filteredList = originalDataList.stream()
                                               .filter(item -> item.getName().toLowerCase().contains(filterPattern))
                                               .collect(Collectors.toList());
            }

            results.values = filteredList;
            results.count = filteredList.size();
            return results;
        }

        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            // 在UI线程更新数据并通知适配器刷新
            currentDataList.clear();
            if (results.values != null) {
                currentDataList.addAll((List<MyItem>) results.values);
            }
            notifyDataSetChanged(); // 通知数据已改变，刷新UI
        }
    }

    // 示例：更新Adapter数据的方法
    public void updateData(List<MyItem> newData) {
        this.originalDataList.clear();
        this.originalDataList.addAll(newData);
        getFilter().filter(null); // 重新过滤或显示全部
    }
}

import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.ListView;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.SearchView;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private SearchView mySearchView;
    private ListView myListView;
    private MyFilterableAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mySearchView = findViewById(R.id.my_search_view);
        myListView = findViewById(R.id.my_list_view);

        // 准备示例数据
        List<MyItem> data = new ArrayList<>();
        data.add(new MyItem("Apple"));
        data.add(new MyItem("Banana"));
        data.add(new MyItem("Cherry"));
        data.add(new MyItem("Date"));
        data.add(new MyItem("Elderberry"));

        adapter = new MyFilterableAdapter(data);
        myListView.setAdapter(adapter);

        // 为SearchView添加TextWatcher
        mySearchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                adapter.getFilter().filter(query);
                return false;
            }

            @Override
            public boolean onQueryTextChange(String newText) {
                // 当文本改变时调用过滤
                adapter.getFilter().filter(newText);
                return false;
            }
        });

        // 如果您坚持使用TextWatcher，也可以这样（但SearchView自带OnQueryTextListener更推荐）
        // 获取SearchView的EditText组件并添加TextWatcher
        /*
        EditText searchEditText = mySearchView.findViewById(androidx.appcompat.R.id.search_src_text);
        searchEditText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {}

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {}

            @Override
            public void afterTextChanged(Editable s) {
                adapter.getFilter().filter(s);
            }
        });
        */
    }
}