<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:orientation="vertical" >    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal" >        <AutoCompleteTextView            android:id="@+id/auto"            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"            android:completionHint="最近5条记录"            android:completionThreshold="1"            />        <Button            android:id="@+id/search"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="搜索" />    </LinearLayout>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="vertical" >        <Button            android:id="@+id/clean"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:text="清除历史记录"             android:onClick="cleanHistory"            />    </LinearLayout></LinearLayout>

public class TestActivity extends Activity {    private AutoCompleteTextView auto;    private Button searchbtn;    private ArrayAdapter<String> arr_adapter;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.test);        // 初始化        auto = (AutoCompleteTextView) findViewById(R.id.auto);        searchbtn = (Button) findViewById(R.id.search);        // 获取搜索记录文件内容        SharedPreferences sp = getSharedPreferences("search_history", 0);        String history = sp.getString("history", "暂时没有搜索记录");        // 用逗号分割内容返回数组        String[] history_arr = history.split(",");        // 新建适配器，适配器数据为搜索历史文件内容        arr_adapter = new ArrayAdapter<String>(this,                android.R.layout.simple_dropdown_item_1line, history_arr);        // 保留前50条数据        if (history_arr.length > 50) {            String[] newArrays = new String[50];            // 实现数组之间的复制            System.arraycopy(history_arr, 0, newArrays, 0, 50);            arr_adapter = new ArrayAdapter<String>(this,                    android.R.layout.simple_dropdown_item_1line, history_arr);        }        // 设置适配器        auto.setAdapter(arr_adapter);        // 设置监听事件，点击搜索写入搜索词        searchbtn.setOnClickListener(new Button.OnClickListener() {            @Override            public void onClick(View v) {                // TODO Auto-generated method stub                save();            }        });    }    public void save() {        // 获取搜索框信息        String text = auto.getText().toString();        SharedPreferences mysp = getSharedPreferences("search_history", 0);        String old_text = mysp.getString("history", "暂时没有搜索记录");                // 利用StringBuilder.append新增内容，逗号便于读取内容时用逗号拆分开        StringBuilder builder = new StringBuilder(old_text);        builder.append(text + ",");        // 判断搜索内容是否已经存在于历史文件，已存在则不重复添加        if (!old_text.contains(text + ",")) {            SharedPreferences.Editor myeditor = mysp.edit();            myeditor.putString("history", builder.toString());            myeditor.commit();            Toast.makeText(this, text + "添加成功", Toast.LENGTH_SHORT).show();        } else {            Toast.makeText(this, text + "已存在", Toast.LENGTH_SHORT).show();        }    }        //清除搜索记录    public void cleanHistory(View v){        SharedPreferences sp =getSharedPreferences("search_history",0);        SharedPreferences.Editor editor=sp.edit();        editor.clear();        editor.commit();        Toast.makeText(this, "清除成功", Toast.LENGTH_SHORT).show();        super.onDestroy();    }    }