我更改了密码。 我从列表视图切换到了recyclerview。 通过使用从数据库获取的数据填充视图，我设法实现了回收器而没有错误。 到目前为止，一切正常。 我想知道“ populateRecyclerLibretto”中的metoto是否可以通过单击按钮来更改顺序。
我有一个按钮，显示了一个微调框，在其中将确认保存为首选项的情况下选择“ orderByColumn”，并启动类populateRecyclerLibretto（）。 这样做对吗？
RecyclerView recycler_libretto;
RecyclerAdapterLibretto adapter_libretto;
LinearLayoutManager linearLayoutManager;
List<DataLibretto> data_libretto = new ArrayList<>();
DBLibretto db;
Cursor cursor_db;
SharedPreferences preferences;
String orderByColumn; //retun value from class getValuePreferences
........
@Override
protected void onResume() {
super.onResume();
db.read();
populateRecyclerLibretto();
}
public DBLibretto read() throws SQLException {
db = dbLibrettoHelper.getReadableDatabase();
return this;
}
public class DataLibretto {
private int id;
private String codice;
private String esame;
private String modo;
private String anno;
private String voto;
private String lode;
private String lode_ctrl;
private String crediti;
private String docente;
private String data;
private String note;
public int getId(){
return id;
}
public String getCodice(){
return codice;
}
public String getEsame(){
return esame;
}
public String getModo(){
return modo;
}
public String getAnno(){
return anno;
}
public String getVoto(){
return voto;
}
public String getLode(){
return lode;
}
public String getLode_ctrl(){
return lode_ctrl;
}
public String getCrediti(){
return crediti;
}
public String getDocente(){
return docente;
}
public String getData(){
return data;
}
public String getNote(){
return note;
}
public void setId(int id){
this.id = id;
}
public void setCodice(String codice){
this.codice = codice;
}
public void setEsame(String esame){
this.esame = esame;
}
public void setModo(String modo){
this.modo = modo;
}
public void setAnno(String anno){
this.anno = anno;
}
public void setVoto(String voto){
this.voto = voto;
}
public void setLode(String lode){
this.lode = lode;
}
public void setLodeCTRL(String lode_ctrl){
this.lode_ctrl = lode_ctrl;
}
public void setCrediti(String crediti){
this.crediti = crediti;
}
public void setDocente(String docente){
this.docente = docente;
}
public void setData(String data){
this.data = data;
}
public void setNote(String note){
this.note = note;
}
}
private void populateRecyclerLibretto() {
data_libretto.clear();
switch (orderByColumn) {
case "_id":
if (value_esami_media) {
//cursorLoader = new CursorLoader(getApplicationContext(),
//ProviderLibretto.CONTENT_URI, allColumns_libretto, "voto NOT LIKE '0' AND voto NOT LIKE '1'", null, orderByColumn);
} else {
cursor_db = db.orderById();
}
break;
case "esame ASC":
if (value_esami_media) {
//cursorLoader = new CursorLoader(getApplicationContext(),
//ProviderLibretto.CONTENT_URI, allColumns_libretto, "voto NOT LIKE '0' AND voto NOT LIKE '1'", null, orderByColumn);
} else {
cursor_db = db.orderByEsameASC();
}
break;
case "esame DESC":
if (value_esami_media) {
//cursorLoader = new CursorLoader(getApplicationContext(),
//ProviderLibretto.CONTENT_URI, allColumns_libretto, "voto NOT LIKE '0' AND voto NOT LIKE '1'", null, orderByColumn);
} else {
cursor_db = db.orderByEsameDESC();
}
break;
case "data ASC":
if (value_esami_media) {
//cursorLoader = new CursorLoader(getApplicationContext(),
//ProviderLibretto.CONTENT_URI, allColumns_libretto, "voto NOT LIKE '0' AND voto NOT LIKE '1'", null, " SUBSTR (data, 7, 10) ASC, SUBSTR(data, 4, 2) ASC, SUBSTR(data, 1, 2) ASC ");
} else {
cursor_db = db.orderByDataASC();
}
break;
case "data DESC":
if (value_esami_media) {
//cursorLoader = new CursorLoader(getApplicationContext(),
//ProviderLibretto.CONTENT_URI, allColumns_libretto, "voto NOT LIKE '0' AND voto NOT LIKE '1'", null, " SUBSTR (data, 7, 10) DESC, SUBSTR(data, 4, 2) DESC, SUBSTR(data, 1, 2) DESC ");
} else {
cursor_db = db.orderByDataDESC();
}
break;
case "anno ASC":
if (value_esami_media) {
//cursorLoader = new CursorLoader(getApplicationContext(),
//ProviderLibretto.CONTENT_URI, allColumns_libretto, "voto NOT LIKE '0' AND voto NOT LIKE '1'", null, orderByColumn);
} else {
cursor_db = db.orderByAnnoASC();
}
break;
case "anno DESC":
if (value_esami_media) {
//cursorLoader = new CursorLoader(getApplicationContext(),
//ProviderLibretto.CONTENT_URI, allColumns_libretto, "voto NOT LIKE '0' AND voto NOT LIKE '1'", null, orderByColumn);
} else {
cursor_db = db.orderByAnnoDESC();
}
break;
case "voto ASC":
if (value_esami_media) {
//cursorLoader = new CursorLoader(getApplicationContext(),
//ProviderLibretto.CONTENT_URI, allColumns_libretto, "voto NOT LIKE '0' AND voto NOT LIKE '1'", null, orderByColumn);
} else {
cursor_db = db.orderByVotoASC();
}
break;
case "voto DESC":
if (value_esami_media) {
//cursorLoader = new CursorLoader(getApplicationContext(),
//ProviderLibretto.CONTENT_URI, allColumns_libretto, "voto NOT LIKE '0' AND voto NOT LIKE '1'", null, orderByColumn);
} else {
cursor_db = db.orderByVotoDESC();
}
break;
case "crediti ASC":
if (value_esami_media) {
//cursorLoader = new CursorLoader(getApplicationContext(),
//ProviderLibretto.CONTENT_URI, allColumns_libretto, "voto NOT LIKE '0' AND voto NOT LIKE '1'", null, orderByColumn);
} else {
cursor_db = db.orderByCreditiASC();
}
break;
case "crediti DESC":
if (value_esami_media) {
//cursorLoader = new CursorLoader(getApplicationContext(),
//ProviderLibretto.CONTENT_URI, allColumns_libretto, "voto NOT LIKE '0' AND voto NOT LIKE '1'", null, orderByColumn);
} else {
cursor_db = db.orderByCreditiDESC();
}
break;
default:
break;
}
while (cursor_db.moveToNext()) {
DataLibretto item = new DataLibretto();
item.setId(cursor_db.getInt(0));
item.setCodice(cursor_db.getString(1));
item.setEsame(cursor_db.getString(2));
item.setModo(cursor_db.getString(3));
item.setAnno(cursor_db.getString(4));
item.setVoto(cursor_db.getString(5));
item.setLode(cursor_db.getString(6));
item.setLodeCTRL(cursor_db.getString(7));
item.setCrediti(cursor_db.getString(8));
item.setDocente(cursor_db.getString(9));
item.setData(cursor_db.getString(10));
item.setNote(cursor_db.getString(11));
data_libretto.add(item); //POPULATE LIST
}
//SET ADAPTER TO RECYCLERVIEW
if((data_libretto.size() !=0)) {
recycler_libretto.setAdapter(adapter_libretto);
}
}
class RecyclerAdapterLibretto extends RecyclerView.Adapter<RecyclerAdapterLibretto.ViewHolder> {
Context context;
List<DataLibretto> dataset_libretto;
private OnRecyclerViewItemClickListener onRecyclerViewItemClickListener; //ItemClickListener
RecyclerAdapterLibretto(Context context, List<DataLibretto> data_libretto) {
this.context = context;
this.dataset_libretto = data_libretto;
}
//ItemClickListener
public void setOnRecyclerViewItemClickListener(OnRecyclerViewItemClickListener onRecyclerViewItemClickListener) {
this.onRecyclerViewItemClickListener = onRecyclerViewItemClickListener;
}
//onCreateViewHolder
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View row = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_libretto_advanced, parent, false);
return new RecyclerAdapterLibretto.ViewHolder(row);
}
//viewHolder
class ViewHolder extends RecyclerView.ViewHolder{
//rowAdvanced
LinearLayout Row_andamento_left;
TextView Row_id;
TextView Row_esame;
ViewHolder(View itemView) {
super(itemView);
//findViewById variabili
Row_andamento_left = itemView.findViewById(R.id.andamento_left_libretto);
Row_id = itemView.findViewById(R.id.row_id_libretto);
Row_id.setTypeface(font_primary, Typeface.BOLD);
Row_esame = itemView.findViewById(R.id.row_esame_libretto);
Row_esame.setTypeface(font_primary, Typeface.BOLD);
//ItemClickListener
itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (onRecyclerViewItemClickListener != null) {
onRecyclerViewItemClickListener.onItemClick(view, getAdapterPosition());
}
}
});
}
}
//onBindViewHolder
@Override
public void onBindViewHolder(final ViewHolder holder, int position) {
//id Debug
holder.Row_id.setText(String.valueOf(dataset_libretto.get(position).getId()));
String esame = dataset_libretto.get(position).getEsame();
}
//getItemCount
@Override
public int getItemCount() {
return dataset_libretto.size();
}
}
int return_sort = picker_set_sort.getValue();
switch (return_sort) {
case 0: //default
orderByColumn = "_id";
populateRecyclerLibretto();
putValuePreferences();
break;
case 1: //esame ASC
orderByColumn = "esame ASC";
populateRecyclerLibretto();
putValuePreferences();
break;
.........
谢谢大家。