我正在学习Android编程并创建REST客户端。我已经用Postman检查了服务器，它工作正常。在Android端，我创建了一个AutoCompleteTextView，它被通过REST接收的数据填充，这不能正常工作。例如，如果我键入'A'，则不会出现列表，但如果我键入'Ap'，然后删除'p'，则会出现一些选项。我检测到它正在正确接收数据，但AutoCompleteTextView中使用的适配器没有清除，也没有正确更新。你能告诉我我错过了什么吗？
下面是我的MainActivity类：

package com.example.connectdb;

import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import androidx.appcompat.app.AppCompatActivity;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = MainActivity.class.getSimpleName();
    private static final String BASE_URL = "http://192.168.0.154:8080/autocomplete/json";
    private AutoCompleteTextView autoCompleteTextView;
    private ArrayAdapter<String> adapter;
    private String[] arr = {};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        autoCompleteTextView = findViewById(R.id.autoCompleteTextView);
        adapter = new ArrayAdapter<>(this, android.R.layout.simple_dropdown_item_1line, arr);
        autoCompleteTextView.setThreshold(1);
        autoCompleteTextView.setAdapter(adapter);
        autoCompleteTextView.addTextChangedListener(textWatcher);
    }
    private final TextWatcher textWatcher = new TextWatcher() {
        private ExecutorService executor = Executors.newSingleThreadExecutor();
        private Handler handler = new Handler(Looper.getMainLooper());
        private List<String> strings;
        public void execute(String string) {
            executor.execute(new Runnable() {
                @Override
                public void run() {
                    strings = backgroundWork(string);
                    handler.post(new Runnable() {
                        @Override
                        public void run() {
                            changeAdapter(strings);
                        }
                    });
                }
            });
        }
        private List<String> backgroundWork(String string) {
            List<String> results = new ArrayList<>();
            try {
                URL url = new URL(BASE_URL);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setRequestMethod("POST");
                connection.setDoInput(true);
                connection.setDoOutput(false);
                connection.addRequestProperty("Content-Length", Integer.toString(6+string.length()));
                connection.addRequestProperty("Content-Type", "application/x-www-form-urlencoded");
                connection.connect();
                OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream());
                writer.write("query="+string);
                writer.flush();
                int responseCode = connection.getResponseCode();
                if (responseCode == HttpURLConnection.HTTP_OK) {
                    InputStream inputStream = connection.getInputStream();
                    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                    StringBuilder stringBuilder = new StringBuilder();
                    String line;
                    while ((line = bufferedReader.readLine()) != null) {
                        stringBuilder.append(line).append('\n');
                    }
                    bufferedReader.close();
                    inputStream.close();
                    JSONArray jsonArray = new JSONArray(stringBuilder.toString());
                    for (int i = 0; i < jsonArray.length(); i++) {
                        JSONObject jsonObject = jsonArray.getJSONObject(i);
                        results.add(jsonObject.getString("interpretation"));
                    }
                }
            } catch (IOException | JSONException e) {
                Log.e(TAG, "Error occurred while searching", e);
            }
            return results;
        }
        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
        }
        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
        }
        @Override
        public void afterTextChanged(Editable editable) {
            String text = autoCompleteTextView.getText().toString().trim();
            if (!text.isEmpty()) execute(text);
        }
    };
    public void changeAdapter(List<String> strings) {
        if (adapter != null) {
            adapter.clear();
            if (strings != null) adapter.addAll(strings);
            adapter.notifyDataSetChanged();
        }
    }
}

activity_main.xml如下：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <AutoCompleteTextView
        android:id="@+id/autoCompleteTextView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:hint="Search..."
        android:imeOptions="actionDone"
        android:inputType="textAutoComplete|textCapWords" />

</RelativeLayout>

AndroidManifest.xml如下：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/Theme.ConnectDB"
        android:usesCleartextTraffic="true"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>