我有一个java.lang.NullPointerException
,但我不知道如何解决。我的用户名未出现在TextView中。
public class Main extends AppCompatActivity {
CircleImageView profilepic;
TextView profileuser;
FirebaseUser firebaseUser;
DatabaseReference reference;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setTitle("");
profilepic = findViewById(R.id.profile_image);
profileuser = findViewById(R.id.username);
firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
reference = FirebaseDatabase.getInstance().getReference("Users").child(firebaseUser.getUid());
reference.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
User user = dataSnapshot.getValue(User.class);
profileuser.setText(user.getUsername());
if (user.getImageURL().equals("default")){
profilepic.setImageResource(R.mipmap.ic_launcher);
}else{
Glide.with(Main.this).load(user.getImageURL()).into(profilepic);
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
日志说我在
profileuser.setText(user.getUsername());
上有错误,请帮助我。这是我的logcat:
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
at com.aceappantipolo.user.aceantipolo.Main$1.onDataChange(Main.java:65)
at com.google.firebase.database.core.ValueEventRegistration.fireEvent(com.google.firebase:firebase-database@@16.0.5:75)
at com.google.firebase.database.core.view.DataEvent.fire(com.google.firebase:firebase-database@@16.0.5:63)
at com.google.firebase.database.core.view.EventRaiser$1.run(com.google.firebase:firebase-database@@16.0.5:55)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:853)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:737)
最佳答案
这通常是因为获取了错误的数据参考。这可能是问题所在:
reference = FirebaseDatabase.getInstance().getReference("Users").child(firebaseUser.getUid());
典型的数据节点名称使用小写字母,因此您可能在这里输入错字。
或者您需要使用以下方法检查您是否具有正确的用户数据:
User user = dataSnapshot.getValue(User.class);
if(user == null) {
// data not found
return;
}
// check for non null user name
if(user.getUsername != null) {
profileuser.setText(user.getUsername());
}
// check for non null image url
if(user.getImageURL() != null) {
if (user.getImageURL().equals("default")){
...
}
}