import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnFocusChangeListener;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.Button;

public class Read_historyActivity extends Activity implements
		OnClickListener {
	private AutoCompleteTextView autoTv;

	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		autoTv = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView1);
		initAutoComplete("history",autoTv);
		Button search = (Button) findViewById(R.id.button1);
		search.setOnClickListener(this);
	}
	@Override
	public void onClick(View v) {
		// 這裡可以設定：當搜尋成功時，才執行儲存操作
		saveHistory("history",autoTv);
	}

	/**
	 * 初始化AutoCompleteTextView，最多顯示5項提示，使
	 * AutoCompleteTextView在一開始獲得焦點時自動提示
	 * @param field 儲存在sharedPreference中的欄位名
	 * @param auto 要操作的AutoCompleteTextView
	 */
	private void initAutoComplete(String field,AutoCompleteTextView auto) {
		SharedPreferences sp = getSharedPreferences("network_url", 0);
		String longhistory = sp.getString("history", "nothing");
		String[]  hisArrays = longhistory.split(",");
		ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
				android.R.layout.simple_dropdown_item_1line, hisArrays);
		//只保留最近的50條的記錄
		if(hisArrays.length > 50){
			String[] newArrays = new String[50];
			System.arraycopy(hisArrays, 0, newArrays, 0, 50);
			adapter = new ArrayAdapter<String>(this,
					android.R.layout.simple_dropdown_item_1line, newArrays);
		}
		auto.setAdapter(adapter);
		auto.setDropDownHeight(350);
		auto.setThreshold(1);
		auto.setCompletionHint("最近的5條記錄");
		auto.setOnFocusChangeListener(new OnFocusChangeListener() {
			@Override
			public void onFocusChange(View v, boolean hasFocus) {
				AutoCompleteTextView view = (AutoCompleteTextView) v;
				if (hasFocus) {
						view.showDropDown();
				}
			}
		});
	}



	/**
	 * 把指定AutoCompleteTextView中內容儲存到sharedPreference中指定的字元段
	 * @param field  儲存在sharedPreference中的欄位名
	 * @param auto  要操作的AutoCompleteTextView
	 */
	private void saveHistory(String field,AutoCompleteTextView auto) {
		String text = auto.getText().toString();
		SharedPreferences sp = getSharedPreferences("network_url", 0);
		String longhistory = sp.getString(field, "nothing");
		if (!longhistory.contains(text + ",")) {
			StringBuilder sb = new StringBuilder(longhistory);
			sb.insert(0, text + ",");
			sp.edit().putString("history", sb.toString()).commit();
		}
	}
}
 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
	xmlns:android="http://schemas.android.com/apk/res/android"
	android:orientation="vertical"
	android:layout_width="fill_parent"
	android:layout_height="fill_parent">
	<TextView android:layout_width="fill_parent"
		android:layout_height="wrap_content"
		android:text="@string/hello" />
	<LinearLayout android:layout_width="0px"
		android:layout_height="0px" android:focusable="true"
		android:focusableInTouchMode="true"></LinearLayout>
	<AutoCompleteTextView
		android:hint="請輸入文字進行搜尋" android:layout_height="wrap_content"
		android:layout_width="match_parent"
		android:id="@+id/autoCompleteTextView1">
	</AutoCompleteTextView>
	<Button android:text="搜尋" android:id="@+id/button1"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"></Button>
</LinearLayout>
 

效果圖如下

    public Filter getFilter() {
        if (mFilter == null) {
            mFilter = new ArrayFilter();
        }
        return mFilter;
    }

 /**
     * <p>An array filter constrains the content of the array adapter with
     * a prefix. Each item that does not start with the supplied prefix
     * is removed from the list.</p>
     */
    private class ArrayFilter extends Filter {
        @Override
        protected FilterResults performFiltering(CharSequence prefix) {
            FilterResults results = new FilterResults();

            if (mOriginalValues == null) {
                synchronized (mLock) {
                    mOriginalValues = new ArrayList<T>(mObjects);
                }
            }

            if (prefix == null || prefix.length() == 0) {
                synchronized (mLock) {
                    ArrayList<T> list = new ArrayList<T>(mOriginalValues);
                    results.values = list;
                    results.count = list.size();
                }
            } else {
                String prefixString = prefix.toString().toLowerCase();

                final ArrayList<T> values = mOriginalValues;
                final int count = values.size();

                final ArrayList<T> newValues = new ArrayList<T>(count);

                for (int i = 0; i < count; i++) {
                    final T value = values.get(i);
                    final String valueText = value.toString().toLowerCase();

                    // First match against the whole, non-splitted value
                    if (valueText.startsWith(prefixString)) {
                        newValues.add(value);
                    } else {
                        final String[] words = valueText.split(" ");
                        final int wordCount = words.length;

                        for (int k = 0; k < wordCount; k++) {
                            if (words[k].startsWith(prefixString)) {
                                newValues.add(value);
                                break;
                            }
                        }
                    }
                }

                results.values = newValues;
                results.count = newValues.size();
            }

            return results;
        }

一些隱藏方法和構造我沒有列舉了，具體可以參考api文件 
可下載我的寫的demo： http://download.csdn.net/detail/iamkila/4042528