java - 当我尝试从创建帐户页面切换到登录页面时，Android 应用程序崩溃

Question

这是登录片段的代码

import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

import com.package.example.MainActivity;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.QuerySnapshot;

import java.util.List;

import static com.CreateAccountFragment.VALID_EMAIL_ADDRESS_REGEX;

/**
 * A simple {@link Fragment} subclass.
 */

public class LoginFragment extends Fragment {

    public LoginFragment() {
        // Required empty public constructor
    }

    private EditText email_or_phone, password;
    private Button login_button;
    private TextView create_button,forgot_password;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_login, container,false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        init(view);

        login_button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                email_or_phone.setError(null);
                password.setError(null);


                if (email_or_phone.getText().toString().isEmpty()){
                    email_or_phone.setError("Required");
                    return;
                }
                if (password.getText().toString().isEmpty()){
                    password.setError("Required");
                    return;
                }

                if (VALID_EMAIL_ADDRESS_REGEX.matcher(email_or_phone.getText().toString()).find()){

                    login(email_or_phone.getText().toString());

                }else if (email_or_phone.getText().toString().matches("\\d{10}")){

                    FirebaseFirestore.getInstance().collection("users").whereEqualTo("phone",email_or_phone.getText().toString())
                            .get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                        @Override
                        public void onComplete(@NonNull Task<QuerySnapshot> task) {
                            if (task.isSuccessful()){
                                List<DocumentSnapshot> document = task.getResult().getDocuments();
                                if (document.isEmpty()){
                                    email_or_phone.setError("This phone is not found");
                                    return;
                                }else{
                                    String email = document.get(0).get("email").toString();
                                    login(email);
                                }

                            }else{
                                String error = task.getException().getMessage();
                                Toast.makeText(getContext(), error, Toast.LENGTH_SHORT).show();
                            }
                        }
                    });


                }else {
                    email_or_phone.setError("Enter a legit Email or phone dude");
                }

            }
        });



        forgot_password.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                ((Registeractivity)getActivity()).setFragment(new ForgotpasswordFragment());
            }
        });

        create_button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                ((Registeractivity)getActivity()).setFragment(new CreateAccountFragment());
            }
        });
    }

    private void init(View view){

        email_or_phone = view.findViewById(R.id.email);
        password = view.findViewById(R.id.password);
        login_button = view.findViewById(R.id.login_button);
        create_button = view.findViewById(R.id.create_button);
        forgot_password = view.findViewById(R.id.forgot_password);
    }

    private void login(String email){
        FirebaseAuth firebaseAuth = FirebaseAuth.getInstance();
        firebaseAuth.signInWithEmailAndPassword(email,password.getText().toString()).addOnCompleteListener(new OnCompleteListener<AuthResult>() {
            @Override
            public void onComplete(@NonNull Task<AuthResult> task) {
                if (task.isSuccessful()){
                    Intent mainIntent = new Intent(getContext(), MainActivity.class);
                    startActivity(mainIntent);
                    getActivity().finish();
                }else{
                    String error = task.getException().getMessage();
                    Toast.makeText(getContext(), error, Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

这是 CreateAccount 片段的代码

import android.os.Build.VERSION_CODES;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import androidx.fragment.app.Fragment;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.SignInMethodQueryResult;

import java.util.Objects;
import java.util.regex.Pattern;

/**
 * A simple {@link Fragment} subclass.

 */
public class CreateAccountFragment extends Fragment {



    public CreateAccountFragment() {
        // Required empty public constructor
    }

    public static final Pattern VALID_EMAIL_ADDRESS_REGEX =
            Pattern.compile("^[A-Z0-9._%+-]+@[A-Z0-9.-]+\\.[A-Z]{2,6}$", Pattern.CASE_INSENSITIVE);

    public static final String EMAIL_REGEX = "^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$";
    private EditText email, phone, password, confirm_password;
    private Button create_button;
    private TextView login_text;
    private FirebaseAuth firebaseAuth;



    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_create_account, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        init(view);

        firebaseAuth = FirebaseAuth.getInstance();

        login_text.setOnClickListener(new View.OnClickListener() {
            @RequiresApi(api = VERSION_CODES.KITKAT)
            @Override
            public void onClick(View view) {

                ((Registeractivity) Objects.requireNonNull(getActivity())).setFragment(new LoginFragment());

            }
        });

        create_button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                email.setError(null);
                phone.setError(null);
                password.setError(null);
                confirm_password.setError(null);
                if (email.getText().toString().isEmpty()){
                    email.setError("Required");
                    return;
                }

                if (phone.getText().toString().isEmpty()){
                    phone.setError("Required");
                    return;
                }

                if (password.getText().toString().isEmpty()){
                    password.setError("Required");
                    return;
                }

                if (confirm_password.getText().toString().isEmpty()){
                    confirm_password.setError("Required");
                    return;
                }
                if (!VALID_EMAIL_ADDRESS_REGEX.matcher(email.getText().toString()).find()){
                    email.setError("Enter a legit Email dude");
                    return;
                }
                if (phone.getText().toString().length() !=10){
                    phone.setError("Enter a legit Phone dude");
                    return;
                }
                if (!password.getText().toString().equals(confirm_password.getText().toString())) {
                    confirm_password.setError("It isn't matching. Chill pill & retype the password !");
                    return;
                }

                create_button();

            }
        });
    }
    private void init(View view) {
        email = view.findViewById(R.id.email);
        phone = view.findViewById(R.id.phone);
        password = view.findViewById(R.id.password);
        confirm_password = view.findViewById(R.id.confirm_password);
        create_button = view.findViewById(R.id.create_button);
        login_text = view.findViewById(R.id.login_button);
    }

    private void create_button(){
        firebaseAuth.fetchSignInMethodsForEmail(email.getText().toString()).addOnCompleteListener(new OnCompleteListener<SignInMethodQueryResult>() {
            @Override
            public void onComplete(@NonNull Task<SignInMethodQueryResult> task) {
                if (task.isSuccessful()){
                    if (task.getResult().getSignInMethods().isEmpty()){
                        ((Registeractivity)getActivity()).setFragment(new OTPFragment(email.getText().toString(),phone.getText().toString(),password.getText().toString()));
                    }else{
                        email.setError("Email exists already dude");
                    }
                }else{
                    String error = task.getException().getMessage();
                    Toast.makeText(getContext(), error, Toast.LENGTH_SHORT).show();
                }
            }
        });
    }

这是我从调试器得到的消息：

E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at com.LoginFragment.onViewCreated(LoginFragment.java:118)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:892)
        at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303)
        at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:439)
        at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2079)
        at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1869)
        at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824)
        at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
        at androidx.fragment.app.FragmentManagerImpl$2.run(FragmentManagerImpl.java:150)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:148)
        at android.app.ActivityThread.main(ActivityThread.java:7331)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)

标签： javaandroidandroid-studio