Question

我正在创建一个Android应用程序，它包含一个列表视图，当单击一个按钮时，列表视图中填充了包含在sqlite中的数据。我做了一些下面的事情我没有收到任何错误，但它没有显示任何检索到的数据。请帮我这个这是我点击按钮时的活动：

fetch_database.setOnClickListener(new View.OnClickListener() {


            @Override
            public void onClick(View v) {

                progressGenerator.start(fetch_database);
                media_player = media_player.create(DatabaseListView.this, R.raw.retrievingfromdatabase);
                media_player.start();


                String[] from = {logindatabase_adapter.USER_NAME,logindatabase_adapter.USER_PASSWORD};
                int[] to = {R.id.txt_username,R.id.txt_pasword};
                cursor = logindatabase_adapter.feching_Data();
                cursoradapter = new SimpleCursorAdapter(DatabaseListView.this, R.layout.listcell, cursor, from, to);
                database_results.setAdapter(cursoradapter);
            }
        });

这是我的logindatabase适配器：

package com.developer.milanandroid;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.view.View;

public class LoginDataBaseAdapter 
{
        //Database name
        static final String DATABASE_NAME = "MilanloginRegistration.db";
        static final int DATABASE_VERSION = 1;
        public static final int NAME_COLUMN = 1;
        // TODO: Create public field for each column in your table.
        // SQL Statement to create a new database.
        public static final String TABLE_NAME="MilanLoginregistration";
        public static final String ID="_id";
        public static final String USER_NAME="USERNAME";
        public static final String USER_PASSWORD ="PASSWORD";


        static final String DATABASE_CREATE = "create table "+ TABLE_NAME +
                                     "( " +ID+" integer primary key autoincrement,"+"USERNAME text UNIQUE,"+USER_PASSWORD+" text); ";
        // Variable to hold the database instance
        public  SQLiteDatabase db;
        // Context of the application using the database.
        private final Context context;
        // Database open/upgrade helper
        private DataBaseHelper dbHelper;
        public  LoginDataBaseAdapter(Context _context) 
        {
            context = _context;
            dbHelper = new DataBaseHelper(context, DATABASE_NAME, null, DATABASE_VERSION);
        }
        public  LoginDataBaseAdapter open() throws SQLException 
        {
            db = dbHelper.getWritableDatabase();
            return this;
        }
        public void close() 
        {
            db.close();
        }

        public  SQLiteDatabase getDatabaseInstance()
        {
            return db;
        }



        public void insertEntry(String username,String password)
        {
           ContentValues newValues = new ContentValues();

            newValues.put("USERNAME",username);
            newValues.put("PASSWORD",password);

            // Insert the row into your table
            db.insert("MilanLoginregistration",null,newValues);
            ///Toast.makeText(context, "Reminder Is Successfully Saved", Toast.LENGTH_LONG).show();
        }
        public int deleteEntry(String username,String password)
        {
            //String id=String.valueOf(ID);
            String where="USERNAME=?";
            int numberOFEntriesDeleted= db.delete("MilanLoginregistration", where, new String[]{username,password}) ;
           // Toast.makeText(context, "Number fo Entry Deleted Successfully : "+numberOFEntriesDeleted, Toast.LENGTH_LONG).show();
            return numberOFEntriesDeleted;
        }

        public Cursor feching_Data(){

            String[] columns = {ID,USER_NAME,USER_PASSWORD};
            db = dbHelper.getWritableDatabase();
            Cursor cursor = db.query(TABLE_NAME, columns,null,null,null,null,null);
            return cursor;

        }
        public String getSinlgeEntry(String userName)
        {
            Cursor cursor=db.query("MilanLoginregistration", null, " USERNAME=?", new String[]{userName}, null, null, null);
            if(cursor.getCount()<1) // UserName Not Exist
            {
                cursor.close();
                return "NOT EXIST";
            }
            cursor.moveToFirst();
            String password= cursor.getString(cursor.getColumnIndex("PASSWORD"));
            cursor.close();
            return password;                
        }
        public String checkSinlgeEntry(String userName)
        {
            Cursor cursor=db.query("MilanLoginregistration", null, " USERNAME=?", new String[]{userName}, null, null, null);
            if(cursor.getCount()>=1) // UserName  Exist
            {
                cursor.close();
                return "NOT EXIST";
            }
            cursor.close();
            return "";              
        }
        public void  updateEntry(String user_name,String pasword)
        {
            // Define the updated row content.
            ContentValues updatedValues = new ContentValues();
            // Assign values for each row.  
            updatedValues.put("USERNAME", user_name);
            updatedValues.put("PASSWORD",pasword);


            String where="USERNAME = ?";
            db.update("MilanLoginregistration",updatedValues, where, new String[]{user_name});             
        }   
        /*public void Display(View v){
            Cursor c = db.rawQuery("select * from MilanloginRegistration", null);
            admin_settings_child.text_fetched_database_results.setText("");
            c.moveToFirst();
            do{
                String username = c.getString(c.getColumnIndex("USERNAME"));
                String password = c.getString(1);
                admin_settings_child.text_fetched_database_results.append("USERNAME::-->"+username+"PASSWORD::-->"+password+"\n");

            }while(c.moveToNext());
        }*/
    }

Answer 1

我建议使用所有推荐的构建模块（游标适配器，内容提供程序，数据加载程序，...... ），而不是重新发明轮子，它会为您节省更多后来很多悲痛。一开始看起来有点复杂，但值得实施。这种方法已在其他地方广为宣传（Lars Vogel，Wolfram Rittmeyer，Udacity Class (Lesson 4) ......）

我在GitHub上放了一个这样的解决方案，您可以自由调查它（附加的APK会显示它的行为）。作为额外的奖励，还有一个PORTRAIT / LANDSCAPE处理具有不同的手机/平板电脑布局。

祝你好运

如何显示从android中的sqlite数据填充的列表视图

1 个答案: