从一个 activity 传递数据并从 Main Activity 显示数据库

Question

这里 Java 的新手 :)

我面临的问题是我无法通过单击按钮从 Main Activity 显示数据库。数据库中的数据是从另一个 activity 传递过来的，想知道我是否遗漏了什么或者我将如何解决这个问题。谢谢:)

（在 onCreate 之后的 Main Activity 中使用的方法）

主要Activity

public void displayDataInTable() {

        roomDatabase myOpenHelper;
        Intent intent = getIntent();
        Bundle bundle = intent.getExtras();
        String status = bundle.getString("status");
        String roomValue =bundle.getString("roomValue");

        //List for the name of the players and their scores
        List<String> roomNumber = new ArrayList<String>();
        List<String> roomStatus = new ArrayList<String>();

        //The data being read from the database
        myOpenHelper = new roomDatabase(this, DATABASE_NAME, null, VERSION_NUMBER);
        SQLiteDatabase db = myOpenHelper.getReadableDatabase();
        Cursor cursor = db.query(roomDatabase.TABLE_NAME, null, null, null, null, null,null,null);

        //The name and the score is printed on the row of the list
        while (cursor.moveToNext()) {
            int id = cursor.getInt(cursor.getColumnIndex("_id"));
            String roomValueA = cursor.getString(cursor.getColumnIndex("roomValue"));
            String statusA = cursor.getString(cursor.getColumnIndex("status"));
            roomNumber.add(roomValueA);
            roomStatus.add(" Recipe Ordered " + statusA);
        }

        //The items to de displayed are sent to the AdapterB
        if ((roomNumber != null) && (roomStatus != null)) {

            AdapterB adapter = new AdapterB(this, roomNumber, roomStatus);
            setListAdapter(adapter);
        }
    }

日志Activity

public class LogsActivity extends ListActivity{

    roomDatabase myOpenHelper;
    final String DATABASE_NAME = "roomstatus.db";
    final int VERSION_NUMBER = 1;
    ContentValues values1 = new ContentValues();

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

        //variables are extracted from the bundle
        Intent intent = getIntent();
        Bundle bundle = intent.getExtras();
        String status = bundle.getString("status");
        String roomValue = bundle.getString("roomValue");

        myOpenHelper = new roomDatabase(this, DATABASE_NAME, null, VERSION_NUMBER);
        SQLiteDatabase db = myOpenHelper.getWritableDatabase();

        values1.put("status", status);
        values1.put("roomValue", roomValue);
        Toast.makeText(LogsActivity.this, status, Toast.LENGTH_LONG).show();
        //Data is entered into the table
        db.insert(roomDatabase.TABLE_NAME, null, values1);

        Intent newIntentBundle = new Intent(LogsActivity.this, MainActivity.class);
        Bundle bundleA = new Bundle();
        bundle.putString("status", status);
        bundle.putString("roomValue", roomValue);
        newIntentBundle.putExtras(bundle);
        startActivity(newIntentBundle);
    }
}

注意 - 我知道这可能不是正确的做法，因为这意味着在 Main Activity 中创建一个新数据库并给适配器带来麻烦，所以任何帮助将不胜感激。 :)

Answer 1

为数据库创建一个单独的 class。以下是有关如何在 android.

中创建 SQLite 数据库的一些链接

Answer 2

这些是在 RoomDatabase 中保存和获取的方法 class:-

    public boolean addDetails(String status,String roomValue){
            SQLiteDatabase db=this.getWritableDatabase();
            ContentValues values=new ContentValues();

            values.put(KEY_STATUS,status);
            values.put(KEY_ROOMVALUE,roomValue);

            db.insert(TABLE_NAME,null,values);
            db.close();
            return true;
        }
public List<String> getAllDetail(){
        List<String> detailList=new ArrayList<>();
        SQLiteDatabase db=this.getReadableDatabase();
        Cursor cursor=db.rawQuery("select * from "+TABLE_NAME,null);
        String status,roomValue;
        if(cursor.moveToFirst()){
            do{
                status=cursor.getString(cursor.getColumnIndex(KEY_STATUS));
                roomValue=cursor.getString(cursor.getColumnIndex(KEY_ROOMVALUE));


                detailList.add(status);
                detailList.add(roomValue);
            }while (cursor.moveToNext());
        }
        return detailList;
    }

在你的 activity 你必须保存在数据库中的地方：

RoomDatabase  roomDatabase=new RoomDatabase(getContext());
roomDatabase.addDetails(status,roomValue);

在您的 activity 中，您必须从数据库中检索：

RoomDatabase  roomDatabase=new RoomDatabase(getContext());
List<String> detailList=db.getAllDetail();

在detailList中可以得到值。

从一个 activity 传递数据并从 Main Activity 显示数据库

passing data from one activity and displaying the database from the Main Activity

java

android

android-database