Question

我对android编程比较陌生，我对如何获取数据库数据有一些问题。我正在尝试创建一个简单的消息传递应用程序数据库中的数据按预期保存，但是当涉及显示问题时。消息活动在视图消息活动显示活动线程时显示所有消息。问题是他的消息活动显示的数据是以降序模式排序的，但每条消息的ID加载ASCENDING，因此消息不会获得他们的实际会话线程。我想知道为什么消息id以升序方式加载。我的代码如下：

消息活动

package com.package.name;

import android.annotation.TargetApi;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.PopupMenu;

import java.util.ArrayList;


public class MessageActivity extends ActionBarActivity {
private ListView obj;
DBHelper mydb;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_message);

    mydb = new DBHelper(this);
    ArrayList array_list = mydb.getAllMessages();
    ArrayAdapter arrayAdapter=new ArrayAdapter(this,android.R.layout.simple_list_item_1, array_list);

    obj = (ListView)findViewById(R.id.list);
    obj.setAdapter(arrayAdapter);
    obj.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
            // TODO Auto-generated method stub
            int id_To_Search = arg2 + 1;

            Bundle dataBundle = new Bundle();
            dataBundle.putInt("id", id_To_Search);

            Intent intent = new Intent(getApplicationContext(), ViewMessage.class);

            intent.putExtras(dataBundle);
            startActivity(intent);
        }
    });
}

查看讯息活动

package com.package.name;

import android.content.Context;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.util.ArrayList;


public class ViewMessage extends ActionBarActivity {

private ListView obj;
DBHelper mydb;

private int msgId;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_view_message);
    Bundle extras = getIntent().getExtras();
    Integer msgId = extras.getInt("id");

    mydb = new DBHelper(this);
    ArrayList array_list = mydb.getAllConversations(msgId);
    ArrayAdapter arrayAdapter=new ArrayAdapter(this,android.R.layout.simple_list_item_1, array_list);

    obj = (ListView)findViewById(R.id.list);
    obj.setAdapter(arrayAdapter);
}
}

DBHELPER

public class DBHelper extends SQLiteOpenHelper {

public static final String DATABASE_NAME = "sdDemoDb.db";
public static final String CONTACTS_TABLE_NAME = "contacts";
public static final String CONTACTS_COLUMN_ID = "id";
public static final String CONTACTS_COLUMN_NAME = "name";
public static final String CONTACTS_COLUMN_EMAIL = "email";
public static final String CONTACTS_COLUMN_STREET = "street";
public static final String CONTACTS_COLUMN_CITY = "place";
public static final String CONTACTS_COLUMN_PHONE = "phone";

//MESSAGE DETAILS TABLE
public static final String MESSAGES_TABLE_NAME = "messages";
public static final String MESSAGES_COLUMN_ID = "id";
public static final String MESSAGES_USER_ID = "user_id";
public static final String MESSAGES_COLUMN_SUBJECT = "subject";
public static final String MESSAGES_COLUMN_CATEGORY = "category";
public static final String MESSAGES_STATUS = "status";
public static final String MESSAGES_CREATED_AT = "created_at";

//CONVERSATION DETAILS TABLE
public static final String CONVERSATION_TABLE_NAME = "conversation";
public static final String CONVERSATION_COLUMN_ID = "id";
public static final String CONVERSATION_COLUMN_MESSAGE_ID = "message_id";
public static final String CONVERSATION_COLUMN_TYPE = "type";
public static final String CONVERSATION_COLUMN_MESSAGE = "message";
public static final String CONVERSATION_STATUS = "status";
public static final String CONVERSATION_CREATED_AT = "created_at";
private HashMap hp;

public DBHelper(Context context)
{
    super(context, DATABASE_NAME , null, 1);
}

@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub
    db.execSQL(
            "create table " + MESSAGES_TABLE_NAME + "("
                    + MESSAGES_COLUMN_ID + " integer primary key autoincrement, "
                    + MESSAGES_USER_ID + " integer, "
                    + MESSAGES_COLUMN_SUBJECT + " text, "
                    + MESSAGES_COLUMN_CATEGORY + " text, "
                    + MESSAGES_STATUS + " text, "
                    + MESSAGES_CREATED_AT + " text)"
    );
    db.execSQL(
            "create table " + CONVERSATION_TABLE_NAME + "("
                    + CONVERSATION_COLUMN_ID + " integer primary key autoincrement, "
                    + CONVERSATION_COLUMN_MESSAGE_ID + " integer, "
                    + CONVERSATION_COLUMN_MESSAGE + " text, "
                    + CONVERSATION_COLUMN_TYPE + " text, "
                    + CONVERSATION_STATUS + " text, "
                    + CONVERSATION_CREATED_AT + " text)"
    );
    db.execSQL(
            "create table contacts " +
                    "(" + CONTACTS_COLUMN_ID + " integer primary key autoincrement, name text,phone text,email text, street text,place text)"
    );
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub
    db.execSQL("DROP TABLE IF EXISTS " + MESSAGES_TABLE_NAME);
    db.execSQL("DROP TABLE IF EXISTS " + CONVERSATION_TABLE_NAME);
    db.execSQL("DROP TABLE IF EXISTS contacts");
    onCreate(db);
}

public boolean createMessage  (String user_id, String subject, String category, String status, String time, String msg) {

    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(MESSAGES_USER_ID, user_id);
    contentValues.put(MESSAGES_COLUMN_SUBJECT, subject);
    contentValues.put(MESSAGES_COLUMN_CATEGORY, category);
    contentValues.put(MESSAGES_STATUS, status);
    contentValues.put(MESSAGES_CREATED_AT, time);
    long lastId = db.insert(MESSAGES_TABLE_NAME, null, contentValues);
    createConv(lastId, msg, "q", "1", time);
    return true;
}

public boolean createConv  (long msg_id,String msg, String type, String status, String time)
{
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(CONVERSATION_COLUMN_MESSAGE_ID, msg_id);
    contentValues.put(CONVERSATION_COLUMN_MESSAGE, msg);
    contentValues.put(CONVERSATION_COLUMN_TYPE, type);
    contentValues.put(CONVERSATION_STATUS, status);
    contentValues.put(CONVERSATION_CREATED_AT, time);
    db.insert(CONVERSATION_TABLE_NAME, null, contentValues);
    return true;
}

public boolean insertContact  (String name, String phone, String email, String street,String place)
{
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put("name", name);
    contentValues.put("phone", phone);
    contentValues.put("email", email);
    contentValues.put("street", street);
    contentValues.put("place", place);
    db.insert("contacts", null, contentValues);
    return true;
}

public int numberOfRows(){
    SQLiteDatabase db = this.getReadableDatabase();
    int numRows = (int) DatabaseUtils.queryNumEntries(db, CONTACTS_TABLE_NAME);
    return numRows;
}

public boolean updateMessage (Integer id, String user_id, String subject, String category, String status, String time, String msg)
{
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(MESSAGES_USER_ID, user_id);
    contentValues.put(MESSAGES_COLUMN_SUBJECT, subject);
    contentValues.put(MESSAGES_COLUMN_CATEGORY, category);
    contentValues.put(MESSAGES_STATUS, status);
    contentValues.put(MESSAGES_CREATED_AT, time);
    db.update(MESSAGES_TABLE_NAME, contentValues, MESSAGES_COLUMN_ID +" = ? ", new String[] { Integer.toString(id) } );
    return true;
}

public boolean updateContact (Integer id, String name, String phone, String email, String street,String place)
{
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put("name", name);
    contentValues.put("phone", phone);
    contentValues.put("email", email);
    contentValues.put("street", street);
    contentValues.put("place", place);
    db.update("contacts", contentValues, "id = ? ", new String[] { Integer.toString(id) } );
    return true;
}

public Integer deleteContact (Integer id)
{
    SQLiteDatabase db = this.getWritableDatabase();
    return db.delete("contacts",
            "id = ? ",
            new String[] { Integer.toString(id) });
}

public ArrayList<String> getAllMessages() {
    ArrayList<String> array_list = new ArrayList<String>();

    //hp = new HashMap();
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor res =  db.rawQuery( "SELECT * FROM " + MESSAGES_TABLE_NAME + " ORDER BY " + MESSAGES_COLUMN_ID + " DESC", null);
    res.moveToFirst();

    while(res.isAfterLast() == false){
        array_list.add(res.getString(res.getColumnIndex(MESSAGES_COLUMN_SUBJECT)));
        res.moveToNext();
    }
    return array_list;
}

public ArrayList<String> getAllConversations(Integer msgId) {
    ArrayList<String> array_list = new ArrayList<String>();

    //hp = new HashMap();
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor res =  db.rawQuery( "SELECT * FROM " + CONVERSATION_TABLE_NAME + " WHERE " + CONVERSATION_COLUMN_MESSAGE_ID  + " = " + msgId + " ORDER BY " + CONVERSATION_COLUMN_ID + " ASC", null);
    res.moveToFirst();

    while(res.isAfterLast() == false){
        array_list.add(res.getString(res.getColumnIndex(CONVERSATION_COLUMN_MESSAGE)));
        res.moveToNext();
    }
    return array_list;
}

public ArrayList<String> getAllCotacts() {
    ArrayList<String> array_list = new ArrayList<String>();

    //hp = new HashMap();
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor res =  db.rawQuery( "SELECT * FROM " + CONTACTS_TABLE_NAME + " ORDER BY " + CONTACTS_COLUMN_ID + " DESC", null);
    res.moveToFirst();

    while(res.isAfterLast() == false){
        array_list.add(res.getString(res.getColumnIndex(CONTACTS_COLUMN_NAME)));
        res.moveToNext();
    }
    return array_list;
}
}

Answer 1

尝试更改

int id_To_Search = arg2 + 1;

成：

int id_To_Search = arg0.getCount() - arg2;

Android sqlite数据库数据显示异常

1 个答案: