Question

我的代码有问题，无法显示新活动的数据（来自先前活动的输入）。

这是我当前的HomepageActivity代码：

private void viewBMI() {
    FirebaseDatabase database = FirebaseDatabase.getInstance();
    final String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
    DatabaseReference myRef = database.getReference("Users").child("bmi").child(uid);

    // Read from the database
    myRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

            String finalBmi = (String) dataSnapshot.getValue();
            showBMI.setText("BMI:  " + String.valueOf(finalBmi));

        }
        @Override
        public void onCancelled(@NonNull DatabaseError error) {
            // Failed to read value
            //Log.w(BMI, "Failed to read value.", error.toException());
        }
    });

这是上一个活动的代码：

private void updateBMI(double bmi, final FirebaseUser currentUser) {

    kg = Double.parseDouble(inputKg.getText().toString());
    m = Double.parseDouble(inputM.getText().toString());


    metricFormula = new MetricFormula(kg, m);
    imperialFormula = new ImperialFormula(kg, m);

    //bmi = String.valueOf(TWO_DECIMAL_PLACES.format(metricFormula.computeBMI(metricFormula.getInputKg(),metricFormula.getInputM())));
    bmi = Double.parseDouble(TWO_DECIMAL_PLACES.format(metricFormula.computeBMI(metricFormula.getInputKg(),metricFormula.getInputM())));

    final double finalBmi = bmi;

    mAuth.updateCurrentUser(currentUser).addOnCompleteListener(this, new OnCompleteListener<Void>() {
        @Override
        public void onComplete(@NonNull Task<Void> task) {

            UserProfileChangeRequest profileUpdate = new UserProfileChangeRequest.Builder()
                    .build();

            currentUser.updateProfile(profileUpdate)
                    .addOnCompleteListener(new OnCompleteListener<Void>() {
                        @Override
                        public void onComplete(@NonNull Task<Void> task) {
                            if(task.isSuccessful()){

                                Map<String, Object> values = new HashMap<>();
                                values.put("bmi", finalBmi);

                                FirebaseDatabase.getInstance().getReference("Users")
                                        .child(FirebaseAuth.getInstance().getCurrentUser().getUid())
                                        .updateChildren(values).addOnCompleteListener(new OnCompleteListener<Void>() {
                                    @Override
                                    public void onComplete(@NonNull Task<Void> task) {
                                        //progressBar.setVisibility(View.GONE);
                                        if (task.isSuccessful()) {
                                            //acc successfully registered
                                            showMessage("Account Updated");

                                            updateUI();
                                        }
                                        else{
                                        }
                                    }
                                });

                            }
                        }
                    });
        }
    });

}

//next page
private void updateUI() {

    Intent homepageActivity = new Intent(EditProfileActivity.this,HomepageUser.class);
    //homepageActivity.putExtra("bmi",bmi); //new
    startActivity(homepageActivity);
    finish();

}

Answer 1

我认为，您的参考文献不正确

DatabaseReference myRef = database.getReference("Users").child("bmi").child(uid);

“用户”下没有子级“ bmi”

您的图片中有用户-> JKkaSDGLdkM7HxzBKf1ivJ4G6A03-> bmi ... etc

您需要考虑另一层信息。

Answer 2

您对儿童的访问顺序不正确。正如我在Firebase子层次结构的图像中看到的那样，您在“ userID”下有“ bmi”。因此，替换

DatabaseReference myRef = database.getReference("Users").child("bmi").child(uid);

与

DatabaseReference myRef = database.getReference("Users").child(uid).child("bmi");

由于层次结构是Users-> id-> bmi（杰森对象的组成部分）

如何显示当前用户从Firebase到新活动的特定数据？

2 个答案: