我的代码运行得很好。然后我更新了Android Studio，现在应用程序继续崩溃，并出现以下错误："无法将java.lang.String类型的对象转换为类型。"。如有任何帮助，我们将不胜感激。非常感谢。
Error Log:
2020-05-03 15:15:17.133 24783-24783/com.example.updatedhapana1 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.updatedhapana1, PID: 24783
com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.example.updatedhapana1.Personal_Posts
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertBean(com.google.firebase:firebase-database@@19.3.0:435)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(com.google.firebase:firebase-database@@19.3.0:231)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertToCustomClass(com.google.firebase:firebase-database@@19.3.0:79)
at com.google.firebase.database.DataSnapshot.getValue(com.google.firebase:firebase-database@@19.3.0:203)
at com.firebase.ui.database.ClassSnapshotParser.parseSnapshot(ClassSnapshotParser.java:29)
at com.firebase.ui.database.ClassSnapshotParser.parseSnapshot(ClassSnapshotParser.java:15)
at com.firebase.ui.common.BaseCachingSnapshotParser.parseSnapshot(BaseCachingSnapshotParser.java:36)
at com.firebase.ui.common.BaseObservableSnapshotArray.get(BaseObservableSnapshotArray.java:52)
at com.firebase.ui.database.FirebaseRecyclerAdapter.getItem(FirebaseRecyclerAdapter.java:109)
at com.firebase.ui.database.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:149)
at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:7065)
at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:7107)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:6012)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6279)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6118)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6114)
at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2303)
at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1627)
at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1587)
at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:665)
at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4134)
at androidx.recyclerview.widget.RecyclerView.onMeasure(RecyclerView.java:3540)
at android.view.View.measure(View.java:24710)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6858)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.view.View.measure(View.java:24710)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6858)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1552)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:842)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:721)
at android.view.View.measure(View.java:24710)
at androidx.core.widget.NestedScrollView.measureChildWithMargins(NestedScrollView.java:1534)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at androidx.core.widget.NestedScrollView.onMeasure(NestedScrollView.java:581)
at android.view.View.measure(View.java:24710)
at androidx.drawerlayout.widget.DrawerLayout.onMeasure(DrawerLayout.java:1119)
at android.view.View.measure(View.java:24710)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6858)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at androidx.appcompat.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:143)
at android.view.View.measure(View.java:24710)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6858)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1552)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:842)
2020-05-03 15:15:17.133 24783-24783/com.example.updatedhapana1 E/AndroidRuntime: at android.widget.LinearLayout.onMeasure(LinearLayout.java:721)
at android.view.View.measure(View.java:24710)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6858)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.view.View.measure(View.java:24710)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6858)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1552)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:842)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:721)
at android.view.View.measure(View.java:24710)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6858)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at com.android.internal.policy.DecorView.onMeasure(DecorView.java:749)
at android.view.View.measure(View.java:24710)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:3259)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:2042)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2337)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1930)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:8018)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1163)
at android.view.Choreographer.doCallbacks(Choreographer.java:986)
at android.view.Choreographer.doFrame(Choreographer.java:902)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1148)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7682)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:516)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
public class Personal_Posts {
private String firstname, lastname, profileimage, banner_images;
public Personal_Posts()
{
}
public Personal_Posts(String firstname, String lastname, String profileimage, String banner_images) {
this.firstname = firstname;
this.lastname = lastname;
this.profileimage = profileimage;
this.banner_images = banner_images;
}
public String getFirstname() {
return firstname;
}
public void setFirstname(String firstname) {
this.firstname = firstname;
}
public String getLastname() {
return lastname;
}
public void setLastname(String lastname) {
this.lastname = lastname;
}
public String getProfileimage() {
return profileimage;
}
public void setProfileimage(String profileimage) {
this.profileimage = profileimage;
}
public String getBanner_images() {
return banner_images;
}
public void setBanner_images(String banner_images) {
this.banner_images = banner_images;
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAuth = FirebaseAuth.getInstance();
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
//this tells our system to actually use the toolbar as the actionbar.
drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
//Button to navigate to profile edit page//
Button personal_wall_button = findViewById(R.id.navigate_to_profile_page);
personal_wall_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this, Personal_Wall.class));
}
});
//Button to navigate to profile edit page//
//RecyclerView
mRecyclerView = findViewById(R.id.recyclerView);
mRecyclerView.setHasFixedSize(true);
//RecyclerView
//set layout as Linear Layout
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
//send Query to FirebaseDatabase
mfirebaseDatabase = FirebaseDatabase.getInstance();
UsersReference = mfirebaseDatabase.getReference("Users");
}
//load data into recycler view onStart
@Override
protected void onStart() {
super.onStart();
FirebaseRecyclerOptions<Personal_Posts> options =
new FirebaseRecyclerOptions.Builder<Personal_Posts>()
.setQuery(UsersReference, Personal_Posts.class)
.build();
FirebaseRecyclerAdapter<Personal_Posts, Personal_Post_ViewHolder> firebaseRecyclerAdapter =
new FirebaseRecyclerAdapter<Personal_Posts, Personal_Post_ViewHolder>(options) {
@Override
protected void onBindViewHolder(@NonNull Personal_Post_ViewHolder holder, int position, @NonNull Personal_Posts model) {
holder.textViewFirst.setText(model.getFirstname());
holder.textViewLast.setText(model.getLastname());
Picasso.get().load(model.getBanner_images()).into(holder.imageViewBanner);
Picasso.get().load(model.getProfileimage()).into(holder.imageViewProfilePicture);
}
@NonNull
@Override
public Personal_Post_ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.post_layout, parent, false);
return new Personal_Post_ViewHolder(v);
}
};
firebaseRecyclerAdapter.startListening();
mRecyclerView.setAdapter(firebaseRecyclerAdapter);
}
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.log_out:
LogOut();
break;
}
return true;
}
@Override
public void onBackPressed() {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
// Attempting to create log out button for navigation menu//
private void LogOut() {
FirebaseAuth.getInstance().signOut();
sendToLogin();
}
private void sendToLogin() {
Intent loginIntent = new Intent(MainActivity.this, Login_Activity.class);
startActivity(loginIntent);
finish();
}
}
[1]: https://i.stack.imgur.com/m3A8f.png
正如您的错误日志所示，您正试图将数据保存在Personal_Posts类型的对象中，但从firebase到达的数据具有String类型。所以不能将字符串对象强制转换为Personal_Posts。
检查适配器类中的onBindViewHolder((，您可能会尝试从DataSnapshot获取数据。