求助 mono for android中的问题
下面是我的代码，在机子上面运行的时候总是会出错Activity1.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.Database;
using Android.Database.Sqlite;
namespace MonoAndroidApplication3
{
[Activity(Label = "MonoAndroidApplication3", MainLauncher = true, Icon = "@drawable/icon")]
public class Activity1 : Activity
{
int id;
ListView lvInfo;
EditText txtInfo;
MySQLiteHelper db;
ICursor cur;
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
SetContentView(Resource.Layout.MainWindow);
Button addInfo = FindViewById<Button>(Resource.Id.addInfo);
Button changeInfo = FindViewById<Button>(Resource.Id.changeInfo);
Button DelInfo = FindViewById<Button>(Resource.Id.DelInfo);
txtInfo = FindViewById<EditText>(Resource.Id.txtInfo);
db = new MySQLiteHelper(this);
try
{
lvInfo = FindViewById<ListView>(Resource.Id.lvInfo);
txtInfo = FindViewById<EditText>(Resource.Id.tvInfo);
cur = db.Select();
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, Resource.Layout.listitem, cur, new string[] { "message" }, new int[] { Resource.Id.txtView });
lvInfo.Adapter = adapter;
lvInfo.ItemClick += (sender, e) =>
{
cur.MoveToPosition(e.Position);
id = cur.GetInt(0);
txtInfo.Text = cur.GetString(1);
};
lvInfo.ItemSelected += (sender, e) =>
{
SQLiteCursor sc = (sender as AdapterView).SelectedItem as SQLiteCursor;
id = sc.GetInt(0);
txtInfo.Text = sc.GetString(1);
};
}
catch (System.Exception ex)
{
}
addInfo.Click += (sender,e) =>
{
if (string.IsNullOrEmpty(txtInfo.Text))
return;
db.Insert(txtInfo.Text);
Init();
};
changeInfo.Click += (sender, e) =>
{
if (string.IsNullOrEmpty(txtInfo.Text) || id == 0)
return;
try
{
db.Update(id, txtInfo.Text);
Init();
}
catch (System.Exception ex)
{
}
};
DelInfo.Click += (sender, e) =>
{
if (id == 0)
return;
db.Delete(id);
Init();
};
}
private void Init()
{
try
{
cur.Requery();//就是在这里出的错，这句代码运行不了，这是为啥捏？
lvInfo.InvalidateViews();
txtInfo.Text = "";
id = 0;
}
catch (SystemException ex)
{
txtInfo.Text = "error 1";
}
}
}
}
mono 貌似网上资料很少，求会的大哥大姐交下，明天就要检查了
还有一个类：MySQLiteHelper.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
namespace MonoAndroidApplication3
{
public class MySQLiteHelper : Android.Database.Sqlite.SQLiteOpenHelper
{
//调用基类的构造函数，数据库名字为Data
public MySQLiteHelper(Context context)
: base(context, "Data", null, 1)
{ }
//在OnCreate中新建数据库表Memo，有num字段及message字段
public override void OnCreate(Android.Database.Sqlite.SQLiteDatabase db)
{
string sql = "create table Info(num integer primary key autoincrement,message text)";
db.ExecSQL(sql);
}
//更新数据库时先将Memo删除再重新创建
public override void OnUpgrade(Android.Database.Sqlite.SQLiteDatabase db, int oldVersion, int newVersion)
{
string sql = "drop table if exists Info";
db.ExecSQL(sql);
OnCreate(db);
}
//查出Info表中的数据
public Android.Database.ICursor Select()
{
return this.ReadableDatabase.Query("Info", null, null, null, null, null, null);
}
//向Info中插入一条新数据
public long Insert(string newmessage)
{
ContentValues values = new ContentValues();
values.Put("message", newmessage);
return this.ReadableDatabase.Insert("Info", null, values);
}
//删除Info中一条记录
public void Delete(int num)
{
this.ReadableDatabase.Delete("Info", "num=?", new string[] { num.ToString() });
}
//根据num修改Info的记录
public void Update(int num, string info)
{
ContentValues values = new ContentValues();
values.Put("message ", info);
this.ReadableDatabase.Update("Info", values, "num=?", new string[] { num.ToString() });
}
}
}
布局的代码我就不上传了 - - --------------------编程问答-------------------- 什么问题，有打印错误信息吗 --------------------编程问答--------------------
是private void Init()
{
try
{
cur.Requery();//就是在这里出的错，这句代码运行不了，这是为啥捏？
lvInfo.InvalidateViews();
txtInfo.Text = "";
id = 0;
}
catch (SystemException ex)
{
txtInfo.Text = "error 1";
}
}
这里出了问题，没有报错，但是就是会运行catch里面的语句，把那句注释掉就不会转到catch执行了，为什么呢？是不是我的数据库操作有问题？还是其他地方出了问题？ --------------------编程问答-------------------- --------------------编程问答-------------------- 看不懂，这个好像是C#啊
补充：移动开发 , Android
