Android 我是否使用正确的方法从数据库中读取数据
我有一个新闻应用程序,该应用程序有一个自定义gridView,其中包括appTitle、AppNewNewCount 在我的数据库表中,我有一个列,它的名称是new,每当向表中添加一个新字段时,它的值就变成1,每当用户单击一条新闻时,它的值就变成0 在具有gridView的活动中,我使用了此函数,该函数指向我的SQLiteOpenHelper数据库类: 我使用以下代码调用函数:Android 我是否使用正确的方法从数据库中读取数据,android,gridview,android-sqlite,sqliteopenhelper,Android,Gridview,Android Sqlite,Sqliteopenhelper,我有一个新闻应用程序,该应用程序有一个自定义gridView,其中包括appTitle、AppNewNewCount 在我的数据库表中,我有一个列,它的名称是new,每当向表中添加一个新字段时,它的值就变成1,每当用户单击一条新闻时,它的值就变成0 在具有gridView的活动中,我使用了此函数,该函数指向我的SQLiteOpenHelper数据库类: 我使用以下代码调用函数: Toast.makeText(getApplicationContext(), String.valueOf(getN
Toast.makeText(getApplicationContext(), String.valueOf(getNumberofNews("Political")), Toast.LENGTH_LONG).show();
函数的代码为:
private int getNumberofNews(String categoryRequested) {
DB_New_Handler obj = null;
try{
obj = new DB_News_Handler(getApplicationContext());
int newNews = obj.getNumberOfNewNews(categoryRequested);
if (newNews > 0) {
return newRings;
}
}catch (Exception ex){
Log.d("getNumberofNews: ", ex.toString());
}finally{
if (obj != null){
obj.close();
}
}
return 0;
}
这是我在SQLiteOpenHelper中用来收集新新闻数量的函数:
public int getNumberOfNewNews(String categoryName) {
SQLiteDatabase db = null;
Cursor cursor = null;
try{
db = this.getReadableDatabase();
cursor = db.query(TABLE_NEWS, new String[] { KEY_ID,
KEY_NEWS_ID, KEY_NAME, KEY_CATEGORY, KEY_Package_Id,
KEY_FAVORITE, KEY_DATE, KEY_NEW_ADDED }, KEY_CATEGORY + "=?",
new String[] { categoryName }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
Log.d(categoryName + " has ", cursor.getCount() + " new News");
return cursor.getCount();
}catch (Exception ex){
Log.d("getNumberOfNewNews: ", ex.toString());
}finally{
if (cursor != null ){
cursor.close();
}
if (db != null){
db.close();
}
}
return 0;
}
,现在的问题是getNumberOfNewNews函数。当假定它返回0时,它总是返回1。在查询新闻计数后编写数据库更新语句。您的更新应将“密钥添加”字段更改为0。我在您的方法中添加了一条注释,您应该在其中编写更新查询
public int getNumberOfNewNews(String categoryName) {
SQLiteDatabase db = null;
Cursor cursor = null;
try{
db = this.getReadableDatabase();
cursor = db.query(TABLE_NEWS, new String[] { KEY_ID,
KEY_NEWS_ID, KEY_NAME, KEY_CATEGORY, KEY_Package_Id,
KEY_FAVORITE, KEY_DATE, KEY_NEW_ADDED }, KEY_CATEGORY + "=?",
new String[] { categoryName }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
//Write the update method here
Log.d(categoryName + " has ", cursor.getCount() + " new News");
return cursor.getCount();
}catch (Exception ex){
Log.d("getNumberOfNewNews: ", ex.toString());
}finally{
if (cursor != null ){
cursor.close();
}
if (db != null){
db.close();
}
}
return 0;
}
在查询新闻计数后,编写数据库更新语句。您的更新应将“密钥添加”字段更改为0。我在您的方法中添加了一条注释,您应该在其中编写更新查询
public int getNumberOfNewNews(String categoryName) {
SQLiteDatabase db = null;
Cursor cursor = null;
try{
db = this.getReadableDatabase();
cursor = db.query(TABLE_NEWS, new String[] { KEY_ID,
KEY_NEWS_ID, KEY_NAME, KEY_CATEGORY, KEY_Package_Id,
KEY_FAVORITE, KEY_DATE, KEY_NEW_ADDED }, KEY_CATEGORY + "=?",
new String[] { categoryName }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
//Write the update method here
Log.d(categoryName + " has ", cursor.getCount() + " new News");
return cursor.getCount();
}catch (Exception ex){
Log.d("getNumberOfNewNews: ", ex.toString());
}finally{
if (cursor != null ){
cursor.close();
}
if (db != null){
db.close();
}
}
return 0;
}
在查询新闻计数后,编写数据库更新语句。您的更新应将“密钥添加”字段更改为0。我在您的方法中添加了一条注释,您应该在其中编写更新查询
public int getNumberOfNewNews(String categoryName) {
SQLiteDatabase db = null;
Cursor cursor = null;
try{
db = this.getReadableDatabase();
cursor = db.query(TABLE_NEWS, new String[] { KEY_ID,
KEY_NEWS_ID, KEY_NAME, KEY_CATEGORY, KEY_Package_Id,
KEY_FAVORITE, KEY_DATE, KEY_NEW_ADDED }, KEY_CATEGORY + "=?",
new String[] { categoryName }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
//Write the update method here
Log.d(categoryName + " has ", cursor.getCount() + " new News");
return cursor.getCount();
}catch (Exception ex){
Log.d("getNumberOfNewNews: ", ex.toString());
}finally{
if (cursor != null ){
cursor.close();
}
if (db != null){
db.close();
}
}
return 0;
}
在查询新闻计数后,编写数据库更新语句。您的更新应将“密钥添加”字段更改为0。我在您的方法中添加了一条注释,您应该在其中编写更新查询
public int getNumberOfNewNews(String categoryName) {
SQLiteDatabase db = null;
Cursor cursor = null;
try{
db = this.getReadableDatabase();
cursor = db.query(TABLE_NEWS, new String[] { KEY_ID,
KEY_NEWS_ID, KEY_NAME, KEY_CATEGORY, KEY_Package_Id,
KEY_FAVORITE, KEY_DATE, KEY_NEW_ADDED }, KEY_CATEGORY + "=?",
new String[] { categoryName }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
//Write the update method here
Log.d(categoryName + " has ", cursor.getCount() + " new News");
return cursor.getCount();
}catch (Exception ex){
Log.d("getNumberOfNewNews: ", ex.toString());
}finally{
if (cursor != null ){
cursor.close();
}
if (db != null){
db.close();
}
}
return 0;
}
阿拉法特是对的
另外,你必须用两个选择参数来查询你的数据库…例如
public int getNumberOfNewNews(String categoryName) {
SQLiteDatabase db = null;
Cursor cursor = null;
try{
db = this.getReadableDatabase();
cursor = db.query(TABLE_NEWS, new String[] { KEY_ID,
KEY_NEWS_ID, KEY_NAME, KEY_CATEGORY, KEY_Package_Id,
KEY_FAVORITE, KEY_DATE, KEY_NEW_ADDED }, KEY_CATEGORY + "=? AND ",
KEY_NEW_ADDED + "=? ",new String[] { categoryName, "1" }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
//Write the update method here
Log.d(categoryName + " has ", cursor.getCount() + " new News");
return cursor.getCount();
}catch (Exception ex){
Log.d("getNumberOfNewNews: ", ex.toString());
}finally{
if (cursor != null ){
cursor.close();
}
if (db != null){
db.close();
}
}
阿拉法特是对的
另外,你必须用两个选择参数来查询你的数据库…例如
public int getNumberOfNewNews(String categoryName) {
SQLiteDatabase db = null;
Cursor cursor = null;
try{
db = this.getReadableDatabase();
cursor = db.query(TABLE_NEWS, new String[] { KEY_ID,
KEY_NEWS_ID, KEY_NAME, KEY_CATEGORY, KEY_Package_Id,
KEY_FAVORITE, KEY_DATE, KEY_NEW_ADDED }, KEY_CATEGORY + "=? AND ",
KEY_NEW_ADDED + "=? ",new String[] { categoryName, "1" }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
//Write the update method here
Log.d(categoryName + " has ", cursor.getCount() + " new News");
return cursor.getCount();
}catch (Exception ex){
Log.d("getNumberOfNewNews: ", ex.toString());
}finally{
if (cursor != null ){
cursor.close();
}
if (db != null){
db.close();
}
}
阿拉法特是对的
另外,你必须用两个选择参数来查询你的数据库…例如
public int getNumberOfNewNews(String categoryName) {
SQLiteDatabase db = null;
Cursor cursor = null;
try{
db = this.getReadableDatabase();
cursor = db.query(TABLE_NEWS, new String[] { KEY_ID,
KEY_NEWS_ID, KEY_NAME, KEY_CATEGORY, KEY_Package_Id,
KEY_FAVORITE, KEY_DATE, KEY_NEW_ADDED }, KEY_CATEGORY + "=? AND ",
KEY_NEW_ADDED + "=? ",new String[] { categoryName, "1" }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
//Write the update method here
Log.d(categoryName + " has ", cursor.getCount() + " new News");
return cursor.getCount();
}catch (Exception ex){
Log.d("getNumberOfNewNews: ", ex.toString());
}finally{
if (cursor != null ){
cursor.close();
}
if (db != null){
db.close();
}
}
阿拉法特是对的
另外,你必须用两个选择参数来查询你的数据库…例如
public int getNumberOfNewNews(String categoryName) {
SQLiteDatabase db = null;
Cursor cursor = null;
try{
db = this.getReadableDatabase();
cursor = db.query(TABLE_NEWS, new String[] { KEY_ID,
KEY_NEWS_ID, KEY_NAME, KEY_CATEGORY, KEY_Package_Id,
KEY_FAVORITE, KEY_DATE, KEY_NEW_ADDED }, KEY_CATEGORY + "=? AND ",
KEY_NEW_ADDED + "=? ",new String[] { categoryName, "1" }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
//Write the update method here
Log.d(categoryName + " has ", cursor.getCount() + " new News");
return cursor.getCount();
}catch (Exception ex){
Log.d("getNumberOfNewNews: ", ex.toString());
}finally{
if (cursor != null ){
cursor.close();
}
if (db != null){
db.close();
}
}
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