我是Android编程的新手，我的问题是当我从MainActivity更新另一个Activity中的一条记录时，RecyclerView没有刷新。
我有一个带有RecyclerView的ManinActivity，一个用于插入和更新记录的activity_Detail，以及一个用于查看存储在数据库中的项目的activity_CardView。
这是我的代码：
MainActivity：
public class MainActivity extends AppCompatActivity {
private RecyclerView recyclerView;
rvNoteAdapter rvNoteAdapter;
private Toolbar mToolbar;
private FloatingActionButton fab;
private String rowID = null;
NoteDatabaseAdapter note_database;
FloatingActionButton btnAddNewRecord;
android.widget.LinearLayout parentLayout;
LinearLayout layoutDisplayPeople;
TextView tvNoRecordsFound;
ArrayList<create_note> notes;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getAllWidgets();
note_database = new NoteDatabaseAdapter(MainActivity.this,6);
bindWidgetsWithEvent();
//displayAllRecords();
Recycler_do();
mToolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(mToolbar);
//getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK) {
String note_type = data.getStringExtra(Constants.COLUMN_NOTE_TYPE);
String note_text = data.getStringExtra(Constants.COLUMN_NOTE_TEXT);
String note_id = data.getStringExtra(Constants.ID);
create_note note = new create_note();
note.setType(note_type);
note.setText(note_text);
if (requestCode == Constants.ADD_RECORD) {
//sQLiteHelper.insertRecord(firstname, lastname);
note_database.insert(note);
//recyclerAdapterNote.addItem(0,note);
} else if (requestCode == Constants.UPDATE_RECORD) {
note.setId(note_id);
//sQLiteHelper.updateRecord(firstname, lastname, rowID);
note_database.update(note);
}
Recycler_do();
}
}
private void getAllWidgets() {
btnAddNewRecord = (FloatingActionButton) findViewById(R.id.fab);
parentLayout = (LinearLayout) findViewById(R.id.parentLayout);
layoutDisplayPeople = (LinearLayout) findViewById(R.id.layoutDisplayNote);
tvNoRecordsFound = (TextView) findViewById(R.id.tvNoRecordsFound);
recyclerView = (RecyclerView) findViewById(R.id.rvNotes);
}
public void Recycler_do ()
{
notes = note_database.getAllRecords();
LinearLayoutManager layoutManager=new LinearLayoutManager(MainActivity.this);
recyclerView.setLayoutManager(layoutManager);
rvNoteAdapter adapter=new rvNoteAdapter(MainActivity.this,contacts);
recyclerView.setAdapter(adapter);
}
private void bindWidgetsWithEvent() {
btnAddNewRecord.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onAddRecord();
}
});
}
private void onAddRecord() {
Intent intent = new Intent(MainActivity.this, Detail.class);
intent.putExtra(Constants.DML_TYPE, Constants.INSERT);
startActivityForResult(intent, Constants.ADD_RECORD);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
activity_Detail：
public class Detail extends AppCompatActivity {
EditText note_type;
EditText note_text;
RecyclerView recyclerView;
NoteDatabaseAdapter noteDatabaseAdapter=new NoteDatabaseAdapter(Detail.this,6);
String id;
String request="";
TextView toolbarText;
ImageView btnDML;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_Detail);
getAllWidgets();
bindWidgetsWithEvent();
checkForRequest();
}
private void checkForRequest() {
request = getIntent().getExtras().get(Constants.DML_TYPE).toString();
if (request.equals(Constants.UPDATE)) {
toolbarText.setText("update");
note_text.setText(getIntent().getExtras().get(Constants.COLUMN_NOTE_TEXT).toString());
note_type.setText(getIntent().getExtras().get(Constants.COLUMN_NOTE_TYPE).toString());
id=getIntent().getExtras().get(Constants.ID).toString();
} else {
toolbarText.setText("new note");
}
}
private void bindWidgetsWithEvent() {
btnDML.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onButtonClick();
}
});
final ImageView back_btn = (ImageView) findViewById(R.id.back_btn);
back_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(Detail.this,"back btn",Toast.LENGTH_LONG).show();
finish(); //back to prev activity
}
});
}
private void getAllWidgets() {
note_type = (EditText) findViewById(R.id.note_type_EB);
note_text = (EditText) findViewById(R.id.note_text_EB);
toolbarText=(TextView) findViewById(R.id.toolbar_text);
btnDML = (ImageView) findViewById(R.id.save_btn);
recyclerView=(RecyclerView) findViewById(R.id.rvNotes);
setTitle(null);
Toolbar topToolBar = (Toolbar)findViewById(R.id.toolbar);
setSupportActionBar(topToolBar);
//topToolBar.setLogo(R.mipmap.ic_launcher);
// topToolBar.setLogoDescription(getResources().getString(R.string.logo_desc));
}
private void onButtonClick() {
if (note_type.getText().toString().equals("") || note_text.getText().toString().equals("")) {
Toast.makeText(getApplicationContext(), "Add Both Fields", Toast.LENGTH_LONG).show();
} else if (request.equals(Constants.INSERT))
{
Intent intent = new Intent();
intent.putExtra(Constants.COLUMN_NOTE_TYPE, note_type.getText().toString());
intent.putExtra(Constants.COLUMN_NOTE_TEXT, note_text.getText().toString());
intent.putExtra(Constants.ID, id);
setResult(RESULT_OK, intent);
finish();
}
else if (request.equals(Constants.UPDATE))
{
create_note note = new create_note();
note.setType(note_type.getText().toString());
note.setText(note_text.getText().toString());
note.setId(id);
try {
noteDatabaseAdapter.update(note);
ArrayList<create_note> noteArrayList = noteDatabaseAdapter.getAllRecords();
ArrayList<create_note> temp=noteDatabaseAdapter.getAllRecords();
rvNoteAdapter rvNoteAdaptermodel=new rvNoteAdapter(Detail.this,temp);
**//do not refresh RecyclerView
rvNoteAdaptermodel.updateItems(noteArrayList);**
}catch (Exception e)
{
Log.d("Database", "Exception:" + e.getMessage());
}
finish();
//
}
}
activity_CardView：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
android:padding="5dp"
>
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/cv">
<RelativeLayout
android:id="@+id/inflateParentView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp"
>
<ImageView
android:contentDescription="@string/action_new"
android:id="@+id/back_btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="end"
android:layout_marginLeft="16dp"
android:layout_marginStart="16dp"
android:src="@mipmap/ic_save"
/>
<TextView
android:layout_toRightOf="@id/back_btn"
android:id="@+id/note_type_inflate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="15dp"
android:layout_weight="1"
android:text="Name"
android:textSize="15sp"
android:gravity="start"
android:textColor="@color/colorPrimary"
android:textStyle="bold"
/>
<TextView
android:layout_toRightOf="@id/back_btn"
android:id="@+id/note_text_inflate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="30dp"
android:layout_weight="1"
android:text="Name"
android:textSize="15sp"
android:gravity="start"
android:textColor="@color/colorPrimary"
android:layout_below="@+id/note_type_inflate" />
<TextView
android:layout_toRightOf="@id/back_btn"
android:id="@+id/note_id_inflate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="30dp"
android:layout_weight="1"
android:text="Name"
android:textSize="15sp"
android:gravity="start"
android:textColor="@color/colorPrimary"
android:layout_below="@+id/note_text_inflate" />
</RelativeLayout>
rvNoteAdapter.java（适用于RecyclerView的适配器）
public class rvNoteAdapter extends RecyclerView.Adapter<rvNoteAdapter.ViewHolder> {
private List<create_note> noteList= Collections.emptyList();
Context noteContext;
private create_note note;
private String rowID = null;
public static class ViewHolder extends RecyclerView.ViewHolder{
public TextView noteText;
public TextView noteType;
public TextView noteId;
private CardView cardView;
public ViewHolder(View itemView){
super(itemView);
noteText=(TextView) itemView.findViewById(R.id.note_text_inflate);
noteType=(TextView) itemView.findViewById(R.id.note_type_inflate);
noteId=(TextView) itemView.findViewById(R.id.note_id_inflate);
cardView = (CardView) itemView.findViewById(R.id.cv);
}
}
public rvNoteAdapter(Context context,List<create_note> Note_List){
this.noteList=Note_List;
this.noteContext=context;
}
private Context getNoteContext()
{
return noteContext;
}
@Override
public rvNoteAdapter.ViewHolder onCreateViewHolder (ViewGroup parent,int viewType)
{
// Context context=parent.getContext();
// LayoutInflater inflater=LayoutInflater.from(context);
//View NoteView=inflater.inflate(R.layout.activity_CardView,parent,false);
//ViewHolder viewHolder=new ViewHolder(NoteView);
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.activity_CardView, parent, false);
ViewHolder memberViewHolder = new ViewHolder(view);
return memberViewHolder;
}
@Override
public void onBindViewHolder(final rvNoteAdapter.ViewHolder viewHolder,int position)
{
//viewHolder.noteText.setText(noteList.get(position).getText());
create_note note=noteList.get(position);
viewHolder.noteText.setText(note.getText());
viewHolder.noteType.setText(note.getType());
viewHolder.noteId.setText(note.getId());
final int pos=position;
viewHolder.cardView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
create_note note=(create_note)v.getTag();
String note_text=viewHolder.noteText.getText().toString();
String note_type=viewHolder.noteType.getText().toString();
String note_id=viewHolder.noteId.getText().toString();
Intent intent = new Intent(v.getContext(), Detail.class);
intent.putExtra(Constants.COLUMN_NOTE_TYPE, note_type);
intent.putExtra(Constants.COLUMN_NOTE_TEXT, note_text);
intent.putExtra(Constants.ID, note_id);
intent.putExtra(Constants.DML_TYPE, Constants.UPDATE);
v.getContext().startActivity(intent);
// mainActivity.onUpdateRecord(note_text,"jhkhkj",note_id);
Toast.makeText(noteContext,"clicked"+pos,Toast.LENGTH_LONG).show();
}
});
}
//my problem with this code that not refreshed RecyclerView
public void updateItems(ArrayList<create_note> notes)
{
noteList.clear();
noteList.addAll(notes);
notifyDataSetChanged();
}
public void addItem(int position, create_note note) {
try {
noteList.add(position, note);
notifyItemInserted(position);
}
catch (Exception e) {
}
}
public void removeItem(create_note note) {
int position=noteList.indexOf(note);
noteList.remove(position);
notifyItemRemoved(position);
}
@Override
public int getItemCount() {
return noteList.size();
}
NoteDatabaseAdapter.java（数据库适配器）：
public class NoteDatabaseAdapter extends SQLiteOpenHelper {
public static final String TABLE_NAME = "tbl_note";
public static final String ID = "ID";
public static final String COLUMN_NOTE_TYPE = "type";
public static final String COLUMN_NOTE_TEXT = "text";
private SQLiteDatabase database;
public NoteDatabaseAdapter(Context context,int newVersion) {
super(context,"noteDatabase.db",null,newVersion);
}
@Override
public void onCreate(SQLiteDatabase db)
{
try {
String sql = "create table "+ TABLE_NAME + " ( id integer primary key autoincrement NOT NULL," + COLUMN_NOTE_TYPE + " NVARCHAR," + COLUMN_NOTE_TEXT + " NVARCHAR)";
db.execSQL(sql);
}catch (Exception e)
{
Log.d("Database", "Exception:" + e.getMessage());
}
}
@Override
public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion)
{
try{
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(db);
}catch (Exception e)
{
Log.d("Database", "Exception:" + e.getMessage());
}
}
public void insert(create_note note) {
try {
database = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COLUMN_NOTE_TYPE, note.getType());
contentValues.put(COLUMN_NOTE_TEXT, note.getText());
database.insert(TABLE_NAME, null, contentValues);
database.close();
} catch (Exception e) {
Log.d("Database", "Exception:" + e.getMessage());
}
}
public void update(create_note note) {
try {
database = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COLUMN_NOTE_TYPE, note.getType());
contentValues.put(COLUMN_NOTE_TEXT, note.getText());
database.update(TABLE_NAME,contentValues,"id="+note.getId(),null);
database.close();
} catch (Exception e) {
Log.d("Database", "Exception:" + e.getMessage());
}
}
public ArrayList<create_note> getAllRecords() {
database = this.getReadableDatabase();
Cursor cursor = database.rawQuery("SELECT * FROM " + TABLE_NAME, null);
ArrayList<create_note> notes = new ArrayList<create_note>();
create_note note_model;
cursor.moveToLast();
if (cursor.getCount() > 0) {
for (int i = 0; i < cursor.getCount(); i++) {
note_model = new create_note();
note_model.setId( cursor.getString(0));
note_model.setType(cursor.getString(1));
note_model.setText(cursor.getString(2));
notes.add(note_model);
cursor.moveToPrevious();
}
}
cursor.close();
database.close();
return notes;
}
} create_note.java（object class）
public class create_note {
private String id;
private String type;
private String text;
public create_note(){}
public create_note(String type, String text) {
this.type = type;
this.text = text;
}
public create_note(String id, String type, String text) {
this.id = id;
this.type = type;
this.text = text;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getType() {
return type;
}
public void setText(String text) {
this.text = text;
}
public String getText() {
return text;
}
public void setType(String type) {
this.type = type;
}
}
我的问题出现在UpdateItem方法的rvNoteAdapter.java中 adapter.invalidate不起作用，
有人能帮助我吗？
答案 0 :(得分：0)
使用它来设置和刷新recyclelerview的一部分。
if (null == rvNoteAdapter) {
rvNoteAdapter rvNoteAdaptermodel=new
rvNoteAdapter(Detail.this,temp);
rvNoteAdaptermodel.updateItems(noteArrayList);
recyclerView.setAdapter(adapter);
} else {
rvNoteAdaptermodel.updateItems(noteArrayList);
rvNoteAdapter.notifyDataSetChanged();
}
你的updateItems方法应该是，
public void updateItems(ArrayList<create_note> notes)
{
noteList.clear();
noteList.addAll(notes);
}
答案 1 :(得分：0)
我使用此方法更新Recyclerview
MainActivity中的
然后我在DetailActivity中使用这些变量。
DetailActivity中的使用此代码：
ArreyList<create_note> noteArreyList = noteDatabaseAdapter.getAllRecords();
MainActivity.notes.clear();
MainActivity.notes.addAll(noteArreyList);
MainActivity.rvNoteAdapter.notifyDataSetChanged();
我在数据库中提升数据后使用此代码：
noteDatabaseAdapter.update(note);