安卓：使用SimpleCursorAdapter从数据库到ListView中获取数据 [英] Android: Using SimpleCursorAdapter to get Data from Database to ListView
问题描述
我编程一个Android应用程序，应该使用一个数据库来存储数据，并从中读取。使用<一个href="http://web.archive.org/web/20130114103211/http://android10.org/index.php/articlesdatastorage/235-creating-and-using-databases-in-android-one">this教程（上archive.org）我得到了应用程序来创建数据库，我能够创建新条目，但是，我不知道，如何读取数据库来获取存储的数据在ListView 。我知道有这个网站很多类似的问题，但似乎没有人申请的方式，从教程数据库工作。
I am programming an android app that should use a database to store data and read from it. Using this tutorial (on archive.org) I got the app to create a database and I'm able to create new entries, however, I don't know, how to read the database to get the stored data in a ListView. I know there are many similar questions on this website but it seems none of them apply to the way, the database from the tutorial works.
code：
import java.util.Calendar;
import maturarbeit.nicola_pfister.studenttools.database.DBAdapter;
import android.app.AlertDialog.Builder;
import android.app.ListActivity;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.database.Cursor;
import android.os.Bundle;
import android.support.v4.widget.SimpleCursorAdapter;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.ListView;
public class Marks extends ListActivity {
DBAdapter db = new DBAdapter(this);
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.marks);
}
@Override
protected void onPause() {
super.onPause();
db.close();
}
@Override
protected void onResume() {
super.onResume();
db.open();
getData();
}
@SuppressWarnings("deprecation")
private void getData() {
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
android.R.layout.simple_list_item_1,
db.getAllMarks(),
new String[] { "value" },
new int[] { android.R.id.text1 });
ListView listView = (ListView) findViewById(R.id.marks_list);
listView.setAdapter(adapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.marks, menu);
return true;
}
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_add:
Calendar cal = Calendar.getInstance();
int day = cal.get(Calendar.DAY_OF_MONTH);
int month = cal.get(Calendar.MONTH);
final String date = day + "." + month;
Builder builder = new Builder(this);
builder
.setTitle(R.string.dialog_addmarks)
.setItems(R.array.markslist, new OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
@SuppressWarnings("unused")
long id;
String selection = getResources().getStringArray(R.array.markslist)[which];
id = db.insertMark(date, "Default", selection);
}
})
.show();
getData();
break;
case R.id.menu_delete:
//Deleting function yet to be implemented.
break;
}
return super.onOptionsItemSelected(item);
}
}
编辑：ListView控件ID是因为它必须是Android的错误：目录
The ListView ID was wrong since it had to be android:list.
推荐答案
使用在你的联系，每一行都有一个教程数据库格式 _id ， ISBN ，标题和发布者。现在让我们假设你想显示在ListView每一个标题：
Using the database format in the tutorial that you linked to, every row has an _id, isbn, title, and publisher. Now let's assume that you want to display every title in a ListView:
db = new DBAdapter(this);
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
android.R.layout.simple_list_item_1,
db.getAllTitles(),
new String[] { "title" },
new int[] { android.R.id.text1 });
ListView listView = (ListView) findViewById(R.id.list);
listView.setAdapter(adapter);
（你并不需要通过光标自己循环，一个适配器这是否对你的工作！）
(You don't need to loop through the Cursor yourself, an adapter does this work for you!)
在你的SimpleCursorAdapter构造函数的最后两个参数是你错过了什么。他们是从和到参数：
The last two parameters in your SimpleCursorAdapter constructor are what you are missing. They are the "from" and "to" parameters:
- 我们希望得到每本书存储在列名
标题的名字，这是我们距离获得的信息。 - 接下来，我们需要告诉它在哪里走出去：
android.R.id.text1是android.R一个TextView。 layout.simple_list_item_1的布局。 （您可以通过SDK挖，看到了simple_list_item_1.xml文件自己或只相信我的时刻。）
- We want to get the name of each book which is stored in the column name
title, this is where we get the information "from". - Next we need to tell it where "to" go:
android.R.id.text1is a TextView in theandroid.R.layout.simple_list_item_1layout. (You can dig through your SDK and see the simple_list_item_1.xml file yourself or just trust me for the moment.)
现在无论是从和到参数数组，因为我们可以通过信息的多个列，试试这个适配器，以及：
Now both the "from" and "to" parameters are arrays because we can pass more than one column of information, try this adapter as well:
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
android.R.layout.simple_list_item_2,
db.getAllTitles(),
new String[] { "title", "publisher" },
new int[] { android.R.id.text1, android.R.id.text2 });
通过这个适配器在其数据库中的图书将按照标题显示出来，然后出版商。所有我们所要做的是使用布局 android.R.layout.simple_list_item_2 ，它有两个领域，并确定哪些列去哪个TextViews。
With this adapter the books in their database will displayed by title, then publisher. All we had to do is use a layout android.R.layout.simple_list_item_2 that takes two fields and define which columns go to which TextViews.
我希望帮助一点点。还有很多东西要学，但也许这会给你一些基本知识。
I hope that helps a little. There's plenty more to learn but maybe this will give you some basics.
最新的留言
我的头顶部，增加新的数据试试这个后刷新的ListView：
Off the top of my head, to refresh the ListView after adding new data try this:
public void onClick(DialogInterface dialog, int which) {
String selection = getResources().getStringArray(R.array.markslist)[which];
db.insertMark(date, "Default", selection);
cursor.requery();
adapter.notifyDataSetChanged();
}
你必须定义适配器和创造光标的变量，但是那是简单的：
You'll have to define adapter and create a variable for cursor but that's simple:
public class Marks extends ListActivity {
SimpleCursorAdapter adapter;
Cursor cursor;
DBAdapter db = new DBAdapter(this);
...
和改变的getData（）相应的：
And change getData() accordingly:
private void getData() {
cursor = db.getAllMarks();
adapter = new SimpleCursorAdapter(this,
android.R.layout.simple_list_item_1,
cursor,
new String[] { "value" },
new int[] { android.R.id.text1 });
...
}
祝你好运！
这篇关于安卓：使用SimpleCursorAdapter从数据库到ListView中获取数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
