即时通讯无法在搜索页上配置后退按钮，对我来说是Android的新手。
在mainactivity导航栏中单击，将打开searchpage活动。我想知道如何在搜索页操作栏上配置后退按钮，我使用onclick感到恐惧，但这似乎不起作用。这是主要的mainactivity和searchpage类。
谢谢。
Mainactivity.class
public class MainActivity extends Login {
public CardView cardView;
RecyclerView recyclerView;
DatabaseReference reference;
FirebaseRecyclerAdapter<Bookdeets, Bkhomeholder> adapter;
FirebaseRecyclerOptions<Bookdeets> options;
ProgressBar loading;
View header;
NavigationView navbar;
DrawerLayout drawerLayout;
ActionBarDrawerToggle mtoggle;
FirebaseAuth fAuth;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
cardView = (CardView) findViewById(R.id.bookcardview);
reference = FirebaseDatabase.getInstance().getReference();
reference.keepSynced(true);
recyclerView = (RecyclerView) findViewById(R.id.rv);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.addItemDecoration(new DividerItemDecoration(this, LinearLayoutManager.VERTICAL));
loading = (ProgressBar) findViewById(R.id.loading);
navbar = (NavigationView) findViewById(R.id.drawer);
navbar.bringToFront();
drawerLayout = (DrawerLayout) findViewById(R.id.drawerlay);
header = navbar.getHeaderView(0);
mtoggle = new ActionBarDrawerToggle(this, drawerLayout, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowTitleEnabled(false);
drawerLayout.addDrawerListener(mtoggle);
mtoggle.syncState();
fAuth= FirebaseAuth.getInstance();
final String UserId = getIntent().getStringExtra("ID");
options = new FirebaseRecyclerOptions.Builder<Bookdeets>()
.setQuery(reference.child("BookDB"), Bookdeets.class).build();
adapter = new FirebaseRecyclerAdapter<Bookdeets, Bkhomeholder>(options) {
@Override
protected void onBindViewHolder(@NonNull Bkhomeholder holder, final int position, @NonNull Bookdeets model) {
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
final String key = getRef(position).getKey().toString();
Intent i = new Intent(getApplicationContext(), Bookdetailslayouthome.class);
i.putExtra("key", key);
startActivity(i);
}
});
Picasso.get().load(model.getImage()).into(holder.bookimg, new Callback() {
@Override
public void onSuccess() {
loading.setVisibility(View.GONE);
}
@Override
public void onError(Exception e) {
Toast.makeText(getApplicationContext(), "could not get the image", Toast.LENGTH_LONG).show();
loading.setVisibility(View.GONE);
}
});
holder.title.setText(model.getBookname());
}
@NonNull
@Override
public Bkhomeholder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardviewlay, parent, false);
return new Bkhomeholder(view);
}
};
GridLayoutManager gridLayoutManager = new GridLayoutManager(getApplicationContext(), 3);
recyclerView.setLayoutManager(gridLayoutManager);
adapter.startListening();
recyclerView.setAdapter(adapter);
navbar.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
int id = item.getItemId();
drawerLayout.closeDrawers();
if(id== R.id.home) {
drawerLayout.closeDrawer(GravityCompat.START);
}
else if(id== R.id.browse) {
Toast.makeText(getApplicationContext(),"hello",Toast.LENGTH_LONG).show();
}
else if(id== R.id.search) {
Intent search = new Intent(getApplicationContext(), SearchPage.class);
startActivity(search);
}
else if(id== R.id.Profile) {
Intent sendtopro=new Intent(getApplicationContext(), Profile.class);
sendtopro.putExtra("Ukey",UserId);
startActivity(sendtopro);
}
else if(id== R.id.addbkbtn) {
Intent adbk = new Intent(getApplicationContext(), Addbooks.class);
adbk.putExtra("UID","User");
startActivity(adbk);
}
else if(id== R.id.Logoutbtn) {
fAuth.signOut();
Intent intent = new Intent(getApplicationContext(), Login.class);
startActivity(intent);
finish();
}
drawerLayout.closeDrawer(GravityCompat.START);
return true;
}
});
}
@Override
public boolean onOptionsItemSelected(@NonNull MenuItem item) {
if (mtoggle.onOptionsItemSelected(item)) {
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onBackPressed() {
if (drawerLayout.isDrawerOpen(GravityCompat.START)) {
drawerLayout.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
protected void onStart() {
super.onStart();
if (adapter != null)
adapter.startListening();
loading.setVisibility(View.VISIBLE);
}
@Override
protected void onStop() {
super.onStop();
if (adapter != null)
adapter.stopListening();
}
@Override
protected void onResume() {
super.onResume();
if (adapter != null)
adapter.startListening();
}
Searchpage.class
public class SearchPage extends AppCompatActivity {
EditText searchbar;
RecyclerView recyclerView;
DatabaseReference reference;
ArrayList<String> BookNameList;
ArrayList<String> AuthorNameList;
ArrayList<String> PicList;
ArrayList<String> PublisherList;
ArrayList<String> LinkList;
ArrayList<String> DescriptionList;
FirebaseAnalytics mFirebaseAnalytics;
ActionBarDrawerToggle mtoggle;
DrawerLayout drawerLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search_page);
searchbar = (EditText) findViewById(R.id.searchbar);
reference = FirebaseDatabase.getInstance().getReference();
reference.keepSynced(true);
recyclerView = (RecyclerView) findViewById(R.id.rv);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.addItemDecoration(new DividerItemDecoration(this, LinearLayoutManager.VERTICAL));
mFirebaseAnalytics = FirebaseAnalytics.getInstance(this);
mtoggle = new ActionBarDrawerToggle(this, drawerLayout, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
BookNameList = new ArrayList<>();
PublisherList = new ArrayList<>();
AuthorNameList = new ArrayList<>();
LinkList = new ArrayList<>();
PicList = new ArrayList<>();
DescriptionList=new ArrayList<>();
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowTitleEnabled(false);
searchbar.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
@Override
public void afterTextChanged(Editable s) {
if (!s.toString().isEmpty()) {
setAdapter(s.toString());
}
else{
BookNameList.clear();
AuthorNameList.clear();
PicList.clear();
PublisherList.clear();
DescriptionList.clear();
}
}
private void setAdapter(final String searchedString) {
reference.child("BookDB").addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
BookNameList.clear();
AuthorNameList.clear();
PicList.clear();
PublisherList.clear();
DescriptionList.clear();
int counter=0;
for(DataSnapshot snapshot:dataSnapshot.getChildren()){
String uid = snapshot.getKey();
String desc = snapshot.child("Desc").getValue(String.class);
String bookname = snapshot.child("bookname").getValue(String.class);
String author = snapshot.child("author").getValue(String.class);
String image = snapshot.child("image").getValue(String.class);
String publisher = snapshot.child("Publisher").getValue(String.class);
try {
if ((bookname.toLowerCase().contains(searchedString.toLowerCase())) || (author.toLowerCase().contains(searchedString.toLowerCase()))) {
BookNameList.add(bookname);
AuthorNameList.add(author);
PublisherList.add(publisher);
PicList.add(image);
counter++;
}
if(BookNameList.isEmpty() && AuthorNameList.isEmpty())
{
}
}
catch (Exception e){
}
if(counter==15){
break;
}
SearchAdapter searchAdapter = new SearchAdapter(SearchPage.this, BookNameList, AuthorNameList, PicList, PublisherList,DescriptionList,LinkList);
recyclerView.setAdapter(searchAdapter);
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
}); }
@Override
public void onBackPressed() {
Intent gob=new Intent(getApplicationContext(),MainActivity.class);
startActivity(gob);
}
最佳答案
在您的Searchpage活动中更改此内容
@Override
public void onBackPressed() {
Intent gob=new Intent(getApplicationContext(),MainActivity.class);
startActivity(gob);
}
至
@Override
public void onBackPressed() {
super.onBackPressed();
}