Android Studio E/AndroidRuntime: 致命异常: main

Question

我的错误；

java.lang.RuntimeException：无法启动活动 组件信息{com.melikerdemkoc.myvetapp/com.melikerdemkoc.myvetapp.MainActivity}： java.lang.NullPointerException：尝试调用虚拟方法 'java.lang.String com.google.firebase.auth.FirebaseUser.getUid()' 空对象引用

我的代码；

import javax.annotation.Nullable;

public class MainActivity extends AppCompatActivity {
    private static final int GALLERY_INTENT_CODE = 1023 ;
    TextView fullName,email,phone,verifyMsg;
    FirebaseAuth fAuth;
    FirebaseFirestore fStore;
    String userId;
    Button resendCode;
    Button resetPassLocal,changeProfileImage;
    FirebaseUser user;
    ImageView profileImage;
    StorageReference storageReference;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        phone = findViewById(R.id.profilePhone);
        fullName = findViewById(R.id.profileName);
        email    = findViewById(R.id.profileEmail);
        resetPassLocal = findViewById(R.id.resetPasswordLocal);

        profileImage = findViewById(R.id.profileImage);
        changeProfileImage = findViewById(R.id.changeProfile);

        FirebaseApp.initializeApp(this);
        fAuth = FirebaseAuth.getInstance();
        fStore = FirebaseFirestore.getInstance();
        storageReference = FirebaseStorage.getInstance().getReference();

        StorageReference profileRef = storageReference.child("users/"+fAuth.getCurrentUser().getUid()+"/profile.jpg");
        profileRef.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
            @Override
            public void onSuccess(Uri uri) {
                Picasso.get().load(uri).into(profileImage);
            }
        });

        resendCode = findViewById(R.id.resendCode);
        verifyMsg = findViewById(R.id.verifyMsg);


        userId = fAuth.getCurrentUser().getUid();
        user = fAuth.getCurrentUser();

        if(!user.isEmailVerified()){
            verifyMsg.setVisibility(View.VISIBLE);
            resendCode.setVisibility(View.VISIBLE);

            resendCode.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(final View v) {

                    user.sendEmailVerification().addOnSuccessListener(new OnSuccessListener<Void>() {
                        @Override
                        public void onSuccess(Void aVoid) {
                            Toast.makeText(v.getContext(), "Verification Email Has been Sent.", Toast.LENGTH_SHORT).show();
                        }
                    }).addOnFailureListener(new OnFailureListener() {
                        @Override
                        public void onFailure(@NonNull Exception e) {
                            Log.d("tag", "onFailure: Email not sent " + e.getMessage());
                        }
                    });
                }
            });
        }




        DocumentReference documentReference = fStore.collection("users").document(userId);
        documentReference.addSnapshotListener(this, new EventListener<DocumentSnapshot>() {
            @Override
            public void onEvent(@Nullable DocumentSnapshot documentSnapshot, @Nullable FirebaseFirestoreException e) {
                if(documentSnapshot.exists()){
                    phone.setText(documentSnapshot.getString("phone"));
                    fullName.setText(documentSnapshot.getString("fName"));
                    email.setText(documentSnapshot.getString("email"));

                }else {
                    Log.d("tag", "onEvent: Document do not exists");
                }
            }
        });


        resetPassLocal.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                final EditText resetPassword = new EditText(v.getContext());

                final AlertDialog.Builder passwordResetDialog = new AlertDialog.Builder(v.getContext());
                passwordResetDialog.setTitle("Reset Password ?");
                passwordResetDialog.setMessage("Enter New Password > 6 Characters long.");
                passwordResetDialog.setView(resetPassword);

                passwordResetDialog.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // extract the email and send reset link
                        String newPassword = resetPassword.getText().toString();
                        user.updatePassword(newPassword).addOnSuccessListener(new OnSuccessListener<Void>() {
                            @Override
                            public void onSuccess(Void aVoid) {
                                Toast.makeText(MainActivity.this, "Password Reset Successfully.", Toast.LENGTH_SHORT).show();
                            }
                        }).addOnFailureListener(new OnFailureListener() {
                            @Override
                            public void onFailure(@NonNull Exception e) {
                                Toast.makeText(MainActivity.this, "Password Reset Failed.", Toast.LENGTH_SHORT).show();
                            }
                        });
                    }
                });

                passwordResetDialog.setNegativeButton("No", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // close
                    }
                });

                passwordResetDialog.create().show();

            }
        });

        changeProfileImage.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // open gallery
                Intent i = new Intent(v.getContext(), com.melikerdemkoc.myvetapp.EditProfile.class);
                i.putExtra("fullName",fullName.getText().toString());
                i.putExtra("email",email.getText().toString());
                i.putExtra("phone",phone.getText().toString());
                startActivity(i);
//

            }
        });


    }


.

    public void logout(View view) {
        FirebaseAuth.getInstance().signOut();//logout
        startActivity(new Intent(getApplicationContext(), com.melikerdemkoc.myvetapp.Login.class));
        finish();
    }


}

我想使用 firebase 数据库启动我的应用程序，但是当我启动应用程序时我不能这样做；我的应用程序崩溃了。

不要阅读；

我写信是因为我不能发布我的问题我写信是因为我不能发布我的问题

Answer 1

问题

您尝试访问当前用户的尝试似乎不存在。

可能的解决方案

尝试检查用户是否已登录，否则不应运行需要当前用户确认的代码。

这是您的精炼代码。

....
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    phone = findViewById(R.id.profilePhone);
    ....
    resendCode = findViewById(R.id.resendCode);
    verifyMsg = findViewById(R.id.verifyMsg);

    if (fAuth.getCurrentUser() != null) {
        
         verifyUser();
    }
    else {
        Log.d("tag", "The user is not authenticated");
    }

}

验证用户方法

public void verifyUser()
{
    userId = fAuth.getCurrentUser().getUid();
    user = fAuth.getCurrentUser();

    if(!user.isEmailVerified()){
        verifyMsg.setVisibility(View.VISIBLE);
        resendCode.setVisibility(View.VISIBLE);

        resendCode.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(final View v) {

                user.sendEmailVerification().addOnSuccessListener(new OnSuccessListener<Void>() {
                    @Override
                    public void onSuccess(Void aVoid) {
                        Toast.makeText(v.getContext(), "Verification Email Has been Sent.", Toast.LENGTH_SHORT).show();
                    }
                }).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        Log.d("tag", "onFailure: Email not sent " + e.getMessage());
                    }
                });
            }
        });
    }




    DocumentReference documentReference = fStore.collection("users").document(userId);
    documentReference.addSnapshotListener(this, new EventListener<DocumentSnapshot>() {
        @Override
        public void onEvent(@Nullable DocumentSnapshot documentSnapshot, @Nullable FirebaseFirestoreException e) {
            if(documentSnapshot.exists()){
                phone.setText(documentSnapshot.getString("phone"));
                fullName.setText(documentSnapshot.getString("fName"));
                email.setText(documentSnapshot.getString("email"));

            }else {
                Log.d("tag", "onEvent: Document do not exists");
            }
        }
    });


    resetPassLocal.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            final EditText resetPassword = new EditText(v.getContext());

            final AlertDialog.Builder passwordResetDialog = new AlertDialog.Builder(v.getContext());
            passwordResetDialog.setTitle("Reset Password ?");
            passwordResetDialog.setMessage("Enter New Password > 6 Characters long.");
            passwordResetDialog.setView(resetPassword);

            passwordResetDialog.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // extract the email and send reset link
                    String newPassword = resetPassword.getText().toString();
                    user.updatePassword(newPassword).addOnSuccessListener(new OnSuccessListener<Void>() {
                        @Override
                        public void onSuccess(Void aVoid) {
                            Toast.makeText(MainActivity.this, "Password Reset Successfully.", Toast.LENGTH_SHORT).show();
                        }
                    }).addOnFailureListener(new OnFailureListener() {
                        @Override
                        public void onFailure(@NonNull Exception e) {
                            Toast.makeText(MainActivity.this, "Password Reset Failed.", Toast.LENGTH_SHORT).show();
                        }
                    });
                }
            });

            passwordResetDialog.setNegativeButton("No", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // close
                }
            });

            passwordResetDialog.create().show();

        }
    });

    changeProfileImage.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // open gallery
            Intent i = new Intent(v.getContext(), com.melikerdemkoc.myvetapp.EditProfile.class);
            i.putExtra("fullName",fullName.getText().toString());
            i.putExtra("email",email.getText().toString());
            i.putExtra("phone",phone.getText().toString());
            startActivity(i);
        }
    });


}

希望它能解决问题。