java - 如果用户在注册时没有从图库中选择任何照片，我如何提醒用户？

Question

在注册页面，当用户点击“ImageUserPhoto”时，他可以从图库中选择一张图像。当他选择照片并填写所有给定字段时，我的代码工作正常。但如果他不选择任何照片，应用程序就会崩溃。如果他没有在我检查所有字段的同一部分中选择任何照片，我该如何发出警告？提前致谢!!

package com.ayon.austmart.activities;

import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.Toast;


import com.ayon.austmart.R;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.auth.UserProfileChangeRequest;
import com.google.firebase.storage.FirebaseStorage;
import com.google.firebase.storage.StorageReference;
import com.google.firebase.storage.UploadTask;

import de.hdodenhof.circleimageview.CircleImageView;


public class RegisterActivity extends AppCompatActivity {

    CircleImageView ImgUserPhoto;
    static int PReqCode = 1;
    static int REQUESCODE = 1;
    Uri pickedImgUri;


    private EditText userEmail, userPassword, userPassword2, userName;
    private ProgressBar loadingProgress;
    private Button regBtn;
    private Intent homeIntent;

    private FirebaseAuth mAuth;




    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);


        userEmail = findViewById(R.id.Email);
        userPassword = findViewById(R.id.Password);
        userPassword2 = findViewById(R.id.ConfirmPassword);
        userName = findViewById(R.id.Name);
        loadingProgress = findViewById(R.id.progressBarRegister);
        regBtn = findViewById(R.id.buttonRegister);
        loadingProgress.setVisibility(View.INVISIBLE);

        mAuth = FirebaseAuth.getInstance();

        ImgUserPhoto = findViewById(R.id.avatar);



        regBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                regBtn.setVisibility(View.INVISIBLE);
                loadingProgress.setVisibility(View.VISIBLE);
                final String email = userEmail.getText().toString();
                final String password = userPassword.getText().toString();
                final String password2 = userPassword2.getText().toString();
                final String name =userName.getText().toString();

                if(email.isEmpty() || name.isEmpty() || password.isEmpty() || password2.isEmpty() || !password.equals(password2))
                {
                    //something goes wrong... display an error message
                    showMessage("Please verify full fields!!");

                    regBtn.setVisibility(View.VISIBLE);
                    loadingProgress.setVisibility(View.INVISIBLE);




                }

                else
                {


                    //Everything is ok..

                    createUserAccount(email,name,password);


                }
            }
        });



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

                if(Build.VERSION.SDK_INT >= 22)
                {
                    checkAndRequestForPermission();
                }

                else
                {
                    openGallery();
                }


            }
        });

    }

    private void createUserAccount(String email, final String name, String password) {

        //this method create user account with valid email and pass


        mAuth.createUserWithEmailAndPassword(email,password)
                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if(task.isSuccessful())
                        {
                            //user account is created successfully
                            showMessage("Account Created!");
                            //now update the pro pic and username

                            updateUserInfo(name,pickedImgUri,mAuth.getCurrentUser());

                        }

                        else
                        {
                            showMessage("Account creation failed"+task.getException().getMessage());
                            regBtn.setVisibility(View.VISIBLE);
                            loadingProgress.setVisibility(View.INVISIBLE);
                        }
                    }
                });





    }


    private void updateUserInfo(final String name, Uri pickedImgUri, final FirebaseUser currentUser){

        StorageReference mStorage = FirebaseStorage.getInstance().getReference().child("user_photos");
        final StorageReference imageFilePath = mStorage.child(pickedImgUri.getLastPathSegment());
        imageFilePath.putFile(pickedImgUri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
            @Override
            public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
                //image uploaded successfully
                //getting image url

                imageFilePath.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                    @Override
                    public void onSuccess(Uri uri) {
                       // uri contains user image url
                        UserProfileChangeRequest profileUpdate = new UserProfileChangeRequest.Builder()
                                .setDisplayName(name)
                                .setPhotoUri(uri)
                                .build();


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

                                        if(task.isSuccessful())
                                        {
                                            //user info updated successfully

                                            showMessage("Register Complete!");
                                            updateUI();
                                        }

                                    }
                                });


                    }
                });

            }
        });



    }

    private void updateUI() {

          homeIntent = new Intent(getApplicationContext(), Home.class);
    startActivity(homeIntent);
    finish();


    }

    //message show
    private void showMessage(String message) {
        Toast.makeText(getApplicationContext(),message,Toast.LENGTH_LONG).show();

    }

    private void openGallery() {

        //Open gallery intent and wait for user to pick an image

        Intent galleryIntent = new Intent(Intent.ACTION_GET_CONTENT);
        galleryIntent.setType("image/*");
        startActivityForResult(galleryIntent,REQUESCODE);


    }


    public void checkAndRequestForPermission()
    {
        if(ContextCompat.checkSelfPermission(RegisterActivity.this, Manifest.permission.READ_EXTERNAL_STORAGE)
                != PackageManager.PERMISSION_GRANTED)
        {
            if(ActivityCompat.shouldShowRequestPermissionRationale(RegisterActivity.this,Manifest.permission.READ_EXTERNAL_STORAGE))
            {
                Toast.makeText(RegisterActivity.this,"Please accept for required permission",Toast.LENGTH_SHORT ).show();
            }

            else
            {
                ActivityCompat.requestPermissions(RegisterActivity.this,new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},PReqCode);
            }


        }

        else
            openGallery();


    }


    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(resultCode == RESULT_OK && requestCode == REQUESCODE && data !=null)
        {
            //user has successfully picked an image...
            //saving its reference to a Uri variable

            pickedImgUri = data.getData();
            ImgUserPhoto.setImageURI(pickedImgUri);


        }
    }
}

Answer 1

如果用户没有从图库中选择图像，则您的pickedImgUri为空。

因此，当您在单击注册按钮时调用 createUserAccount() 且用户未选择图像pickedImgUri 时，不会根据您的代码进行更新。因此 updateUserInfo() 将无法调用导致崩溃的异常。

请添加一个空检查器，例如

if(pickedImgUri!=null){
    //then update the user account
}

如果您有兴趣强制用户选择个人资料照片，则只需使用上面的检查器并提醒用户请先选择照片，但我建议不要这样做。并不是每个人都喜欢上传照片。当用户不想更新/删除头像时，请使用任何通用头像 png 文件。快乐编码