基于WEBVIEW的手机浏览器，求大神帮忙修改，用eclipse写的，书签不能删除，可有偿

package com.exmple;

import com.riskycheng.Dnet.R;

import android.app.Activity;
import android.content.Intent;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.ContextMenu;
import android.view.MenuItem;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.View.OnClickListener;
import android.view.View.OnCreateContextMenuListener;
import android.view.Window;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.SimpleAdapter;

import java.util.ArrayList;
import java.util.HashMap;

import android.database.Cursor;

public class Bookmark extends Activity {
ArrayList> history_data_list = new ArrayList>();// 用来显示历史的list
private SQLiteHelper sqliteHelper;
private Cursor myCursor;
private ListView history_listview;
private Button back_button;
private MainView mainView;
public static String operaString = null;

@Override
public void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	requestWindowFeature(Window.FEATURE_NO_TITLE);
	setContentView(R.layout.page_bookmark);
	init();
}

public void init() {
	sqliteHelper = new SQLiteHelper(getApplicationContext());
	mainView = new MainView();
	history_listview = (ListView) findViewById(R.id.history_list);
	SimpleAdapter adapter = new SimpleAdapter(getApplicationContext(),
			get_History(), R.layout.history_display_style, new String[] {
					"网页", "网址" }, new int[] { R.id.website_name,
					R.id.website_url });
	history_listview.setAdapter(adapter);

	// 设置ListView的项目按下事件监听
	history_listview.setOnItemClickListener(new OnItemClickListener() {

		public void onItemClick(AdapterView parent, View v,
				int position, long id) {
			MainView.cur_url = history_data_list.get(position).get("网址")
					.toString();
			// MainView.instance.visit(MainView.cur_url);
			Intent intent = new Intent();
			intent.setClass(getApplicationContext(), MainView.class);
			startActivity(intent);
		}
	});
	// 设置ListView的项目长按下事件监听
	history_listview.setOnItemLongClickListener(new ListItemLongClick());
	history_listview.setOnCreateContextMenuListener(new ListonCreate());

}

public boolean onContextItemSelected(MenuItem item) {
	switch (item.getItemId()) {
	case 0:
		//modify
		break;
	case 1:
		// 删除操作
		Log.e("opera", operaString);
		sqliteHelper.delete_single_record(operaString);
		Intent intent = new Intent();
		intent.setClass(getApplicationContext(), Bookmark.class);
		startActivity(intent);
		break;
	default:
		break;
	}
	return super.onContextItemSelected(item);

}

public ArrayList> get_History() {
	SQLiteDatabase db = sqliteHelper.getWritableDatabase();
	myCursor = db.query(sqliteHelper.TB__HISTORY_NAME, new String[] {
			HistoryBean.NAME, HistoryBean.URL }, "isbookmark=1", null,
			null, null, HistoryBean.TIME + " DESC");
	int url = myCursor.getColumnIndex(HistoryBean.URL);
	int name = myCursor.getColumnIndex(HistoryBean.NAME);
	history_data_list.clear();
	if (myCursor.moveToFirst()) {
		do {
			HashMap item = new HashMap();
			item.put("网页", myCursor.getString(name));
			item.put("网址", myCursor.getString(url));
			history_data_list.add(item);
		} while (myCursor.moveToNext());
	}
	myCursor.close();
	return history_data_list;
}

// 长按弹出菜单事件类
private class ListonCreate implements OnCreateContextMenuListener {

	public void onCreateContextMenu(ContextMenu menu, View arg1,
			ContextMenuInfo arg2) {
		menu.setHeaderTitle(R.string.long_click_bookmark_title);
		menu.add(0, 0, 0, R.string.modify);
		menu.add(0, 1, 0, R.string.delete);
	}

}

// 长按事件类
private class ListItemLongClick implements OnItemLongClickListener {

	public boolean onItemLongClick(AdapterView parent, View view,
			int position, long arg3) {
		Log.e("tag", history_data_list.get(position).get("网页").toString());
		operaString = history_data_list.get(position).get("网页").toString();
		return false;
	}

}

}