app把信息添加到mysql_如何将数据库表中的数据添加到ListView C#Xamarin Android App
几天前我问过如何在活动之间共享数据,一个用户告诉我使用SQLite,所以我做了.我想让用户点击MainLayout中的按钮,它会将他重定向到AddTaskLayout,在那里他可以添加任务名称,按下Save按钮应用程序会将他重定向回MainLayout,他的任务将在ListView中列出.
到目前为止,我创建了数据库,表格和我需要的一切.我的问题是：如何将存储在数据库表中的数据添加到ListView？我发现的每个答案都是用Java编写的,所以搜索旧的StackOverflow问题并没有那么有用：/
这是代码：
我的DBRepository是表示创建数据库,创建表,向表插入数据以及获取相同数据的类：
public class DBRepository
{
public void CreateDatabase()
{
string dbPath = Path.Combine(System.Environment.GetFolderPath
(System.Environment.SpecialFolder.Personal), "database.db3");
var db = new SQLiteConnection(dbPath);
}
public void CreateTable()
{
string dbPath = Path.Combine(System.Environment.GetFolderPath
(System.Environment.SpecialFolder.Personal), "database.db3");
var db = new SQLiteConnection(dbPath);
db.CreateTable();
}
public string InsertRecord(string task)
{
string dbPath = Path.Combine(System.Environment.GetFolderPath
(System.Environment.SpecialFolder.Personal), "database.db3");
var db = new SQLiteConnection(dbPath);
ToDoTasks item = new ToDoTasks();
item.Task = task;
db.Insert(item);
return task;
}
public string GetData()
{
string dbPath = Path.Combine(System.Environment.GetFolderPath
(System.Environment.SpecialFolder.Personal), "database.db3");
var db = new SQLiteConnection(dbPath);
string output = "";
var table = db.Table();
foreach(var item in table)
{
output += item;
}
return output;
}
}
我创建表的ToDoTasks类：
[Table("ToDo")]
public class ToDoTasks
{
[PrimaryKey, AutoIncrement, Column("_Id")]
public int Id { get; set; }
[MaxLength(100)]
public string Task { get; set; }
}
我的AddTaskActivity表示用户输入任务名称的第二个布局：
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
SetContentView(Resource.Layout.AddTask);
//define buttons
Button save, cancel;
save = FindViewById(Resource.Id.save);
cancel = FindViewById(Resource.Id.cancel);
save.Click += save_click;
cancel.Click += cancel_click;
}
private void save_click(object sender, EventArgs e)
{
DBRepository dbr = new DBRepository();
EditText name = FindViewById(Resource.Id.taskName);
//enter user's input(task name) to table
var result = dbr.InsertRecord(name.Text);
StartActivity(typeof(MainActivity));
}
private void cancel_click(object sender, EventArgs e)
{
StartActivity(typeof(MainActivity));
}
我想要填充listView的MainActivity：
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
// Set view
SetContentView(Resource.Layout.Main);
//create database if it doesn't exist
DBRepository dbr = new DBRepository();
dbr.CreateDatabase();
//create table (if it doesn't exist)
dbr.CreateTable();
//Define buttons
Button addTask;
ListView list;
addTask = FindViewById(Resource.Id.addTask);
addTask.Click += addTask_click;
}
private void addTask_click(object sender, EventArgs e)
{
StartActivity(typeof(AddTaskActivity));
}
我非常感谢你的帮助.我知道这些都是非常基本的问题,但有人必须要求他们为自己和许多其他(未来)C#android开发人员.谢谢！
//
更新：我检查了Johan的答案是否正确,但这是(在我的情况下)正确的代码：
我需要更改GetData()方法以返回List(不像以前那样对象),然后在ListView中显示List.这是代码：
You helped me a lot, but I had to make few changes, so here they are for the record:
在DBRepository中需要将GetData()方法更改为：
public List GetData()
{
string dbPath = Path.Combine(System.Environment.GetFolderPath
(System.Environment.SpecialFolder.Personal), "database.db3");
var db = new SQLiteConnection(dbPath);
List data = new List();
foreach (var item in db.Table())
{
var zad = item.Task.ToString();
data.Add(zad);
}
return data;
}
然后,在MainActivity中,ListView的代码只添加：
var items = dbr.GetData();
var listView = FindViewById(Resource.Id.listView);
listView.Adapter = new ArrayAdapter(this, Android.Resource.Layout.SimpleListItem1, items);
我希望将来可以帮助别人.再次感谢大家.
最佳答案 根据我的评论,您需要进行以下更改.
public List GetData()
{
string dbPath = Path.Combine(System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal), "database.db3");
var db = new SQLiteConnection(dbPath);
return db.Table().ToList();
}
然后在您的Activity中,您可以在其中执行以下操作
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
// Set view
SetContentView(Resource.Layout.Main);
//create database if it doesn't exist
DBRepository dbr = new DBRepository();
dbr.CreateDatabase();
//create table (if it doesn't exist)
dbr.CreateTable();
var items = dbr.GetData();
var listView = FindViewById(Android.Resource.Id.ListView);
listView.Adapter = new ArrayAdapter(this, Android.Resource.Layout.SimpleListItem1, items);
}
如果您的活动继承自ListActivity,您可以执行以下操作
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
// Set view
SetContentView(Resource.Layout.Main);
//create database if it doesn't exist
DBRepository dbr = new DBRepository();
dbr.CreateDatabase();
//create table (if it doesn't exist)
dbr.CreateTable();
var items = dbr.GetData();
ListAdapter = new ArrayAdapter(this, Android.Resource.Layout.SimpleListItem1, items);
}
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