Android ListView刷新

Question

我有一个Listview从sqlite数据库拉取并显示数据.数据库第一列中的数据显示在ListView单击中,单击时,Activity开始显示与第一列关联的列的其余部分.编辑数据时ListView需要更新以反映这一点,但除非重新启动应用程序,否则它不会显示更新.

我已经打过电话,notifyDataSetChanged()并startActivityForResult()在我的onResume()方法,但没有奏效.我应该使用什么方法来完成ListView当前代码的更新？

我理解SimpleCursorAdapter可以使用,我试图实现该代码没有成功.我是一个新手,需要实际的代码才能理解需要做什么.

public class LoginList extends Activity implements OnClickListener, OnItemClickListener {
    private ListView loginList;
    private Button webLogin;

    private ListAdapter loginListAdapter;

    private ArrayList<LoginDetails> loginArrayList;

    @Override 
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.login_listview);
        loginList = (ListView)
        findViewById(R.id.loginlist);
        loginList.setOnItemClickListener(this);

        webLogin = (Button)
        findViewById(R.id.button3);
        webLogin.setOnClickListener(this);

        loginArrayList = new ArrayList<LoginDetails>();
        loginListAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, populateList());
        loginList.setAdapter(loginListAdapter);
    }

    @Override
    public void onClick (View v) {
        Intent webLoginIntent = new Intent (this, LoginPlusActivity.class);
        startActivity(webLoginIntent);
    }

    public List<String> populateList () {
        List<String> webNameList = new ArrayList<String>();

        dataStore openHelperClass = new dataStore (this);

        SQLiteDatabase sqliteDatabase = openHelperClass.getReadableDatabase();

        Cursor cursor = sqliteDatabase.query(dataStore.TABLE_NAME_INFOTABLE, null, null, null, null, null, dataStore.COLUMN_NAME_SITE, null);

        startManagingCursor(cursor);

        while (cursor.moveToNext()) {
            String sName = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_SITE));
            String wUrl = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_ADDRESS));
            String uName = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_USERNAME));
            String pWord = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_PASSWORD));
            String lNotes = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_NOTES));

            LoginDetails lpDetails = new LoginDetails();

            lpDetails.setsName(sName);
            lpDetails.setwUrl(wUrl);
            lpDetails.setuName(uName);
            lpDetails.setpWord(pWord);
            lpDetails.setlNotes(lNotes);

            loginArrayList.add(lpDetails);
            webNameList.add(sName);
        }

        sqliteDatabase.close();
        return webNameList;
    }


    @Override
    protected void onResume() {
        super.onResume();

        loginListAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, populateList());
        loginList.setAdapter(loginListAdapter);  

    }


@Override
    public void onItemClick(AdapterView<?> arg0 , View arg1, int arg2, long arg3) {
        Toast.makeText(getApplicationContext(), "Selected ID :" + arg2, Toast.LENGTH_SHORT).show();

        Intent updateDeleteLoginInfo = new Intent (this, UpdateDeleteLoginList.class);
        LoginDetails clickedObject = loginArrayList.get(arg2);

        Bundle loginBundle = new Bundle();
        loginBundle.putString("clickedWebSite",clickedObject.getsName());
        loginBundle.putString("clickedWebAddress",clickedObject.getwUrl());
        loginBundle.putString("clickedUserName",clickedObject.getuName());
        loginBundle.putString("clickedPassWord",clickedObject.getpWord());
        loginBundle.putString("clickedNotes",clickedObject.getlNotes());

        updateDeleteLoginInfo.putExtras(loginBundle);

        startActivityForResult(updateDeleteLoginInfo, 0);   
    }
}

Answer 1

这正是一个Loader伟大的东西.我建议您创建一个SimpleCursorAdapter将数据库绑定到UI(ListView在本例中),一个ContentProvider与数据库的接口,以及一个CursorLoader监视数据库的更改,并在必要时更新UI.在Loader将处理所有DB的变化和更新您ListView只需更新您的适配器.它看起来像预先做了很多工作,但是一旦配置就非常强大,并且将贯穿整个Android生命周期.

这些教程应该是有用的:

• https://developer.android.com/training/load-data-background/index.html
• http://www.vogella.com/articles/AndroidSQLite/article.html#background_loader
• https://github.com/browep/AndroidCursorLoaderTutorial

Answer 2

编辑

private ArrayList<LoginDetails> loginArrayList = new ArrayList<LoginDetails>();;

@Override 
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.login_listview);
    loginList = (ListView)
    findViewById(R.id.loginlist);
    loginList.setOnItemClickListener(this);

    webLogin = (Button)
    findViewById(R.id.button3);
    webLogin.setOnClickListener(this);


    loginListAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,loginArrayList );
    loginList.setAdapter(loginListAdapter);
    populateList();
}

@Override
public void onClick (View v) {
    Intent webLoginIntent = new Intent (this, LoginPlusActivity.class);
    startActivity(webLoginIntent);
}

public void populateList () {
    loginListAdapter.clear();
    loginArrayList.clear();
    dataStore openHelperClass = new dataStore (this);

    SQLiteDatabase sqliteDatabase = openHelperClass.getReadableDatabase();

    Cursor cursor = sqliteDatabase.query(dataStore.TABLE_NAME_INFOTABLE, null, null, null, null, null, dataStore.COLUMN_NAME_SITE, null);

    startManagingCursor(cursor);

    while (cursor.moveToNext()) {
        String sName = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_SITE));
        String wUrl = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_ADDRESS));
        String uName = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_USERNAME));
        String pWord = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_PASSWORD));
        String lNotes = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_NOTES));

        LoginDetails lpDetails = new LoginDetails();

        lpDetails.setsName(sName);
        lpDetails.setwUrl(wUrl);
        lpDetails.setuName(uName);
        lpDetails.setpWord(pWord);
        lpDetails.setlNotes(lNotes);

        loginArrayList.add(lpDetails);
        webNameList.add(sName);
    }
    loginListAdapter.notifyDatasetChanged();
    sqliteDatabase.close();
}

您正在丢失对列表视图的引用,指出您的列表未更新的原因...

在代码中进行此修改.1.声明(全局)时初始化ArrayList.

ArrayList loginArrayList = new ArrayList<LoginDetails>();

1. 直接将分配列表设置为适配器(onCreate)

   loginListAdapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1,loginArrayList);

2. 呼叫populateList()在onCreate().

3. 在您populateList()的新列表中添加与您的适配器关联的现有列表,而不是添加数据loginArrayList

如果您的列表是全新的呼叫,adapter.clear()并且loginArrayList.clear()在populateList()添加数据之前loginArrayList.将数据添加到loginArrayList呼叫后adapter.notifyDataSetChanged()

这应该工作......

Answer 3

我的推荐。

1. 不要循环加载列表。如果它是一个包含所有字符串的简单列表。尝试使用SimpleCursorAdapterand 将使您的应用程序更快、代码更短。
2. 更新数据库后，您要做的就是查询数据库以获取Cursor，并使用Adapter。swapCursor(newCursor)。这将更新您的列表，同时保持滚动位置。