Question

我正在从SQLite数据库中检索纬度数据。

我有一张充满经度和纬度值的表格。

我的查询是：

 public Cursor fetchAllCountries() {
    SQLiteDatabase db=this.getReadableDatabase();
    String SelectQuery="select * from "+ TABLE_NAME;
    Cursor mCursor = db.rawQuery(SelectQuery,null);
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;
}

我的MainActivity.java包含：

Cursor cursor = myDB.fetchAllCountries();

/* for (int i=0;i<list.size();i++) {
    double data=list.get(i);
    System.out.println(data + " ");
}*/

if (cursor.moveToFirst()) {
    do {
        double data = cursor.getDouble(cursor.getColumnIndex("lat"));
        System.out.println(data + " ");
    } while(cursor.moveToNext());
}

Answer 1

public Cursor fetchAllCountries() {
    SQLiteDatabase db=this.getReadableDatabase();
    String SelectQuery="select * from "+ TABLE_NAME;
    Cursor mCursor = db.rawQuery(SelectQuery,null);
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;
}

MainActivity.java

TextView txt = (TextView) findViewById(R.id.textView);
Cursor cursor = myDB.fetchAllCountries();

double[] array = new double[cursor.getCount()];
int i = 0;

if (cursor.moveToFirst()) {
    do {
        double data = cursor.getDouble(cursor.getColumnIndex("lat"));
        array[i] = data;
        txt.append(Double.toString(array[i]));

        i++;
    } while (cursor.moveToNext());
}

Answer 2

这是一个例子。

private static List<Information> getAllInformation(Cursor cursor) {
    List<Information> list = new ArrayList<>();
    if (cursor != null) {
        if (cursor.moveToFirst()) {
            do {
                int id = cursor.getInt(cursor.getColumnIndex(COL_ID));
                String title = cursor.getString(cursor.getColumnIndex(COL_TITLE));
                String mediaName = cursor.getString(cursor.getColumnIndex(COL_MEDIA_NAME));
    Information info = new Information(id, title, mediaName);
                list.add(info);
            } while (cursor.moveToNext());
        }
        if (!cursor.isClosed()) {
            cursor.close();
        }
    }
    return list;
}

public static List< Information > getAllInformation() {
    String sql = "SELECT * FROM " + TABLE_NAME;
    SQLiteDatabase database = this.getReadableDatabase();
    Cursor cursor = database.rawQuery(sql, null);
    return getAllInformation(cursor);
}

在活动中

List<Information> mListAll;
mListAll = YourNameTable.getAllInformation();

Class Information.class

public class Information {
int id;
String title;
String mediaName;

//get
//set

}

如何显示此中的所有lat值

2 个答案: