我对 Android 开发完全陌生，我正在使用我的 Android 应用程序，我的应用程序包括注册和登录活动。所以我正在处理注册活动，但当我点击注册按钮时应用程序停止工作。
而且我也知道这是因为 NullPointerException 但我无法解决问题。
我收到的错误是应用程序意外停止...希望我为你们说清楚。
注册活动.java
package com.example.kiit.shoppar;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
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.auth.FirebaseUser;
import com.google.firebase.auth.UserProfileChangeRequest;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Locale;
public class SignupActivity extends AppCompatActivity {
Button reg;
EditText fname, lname, pass, inputEmail, phone;
FirebaseAuth auth;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_signup);
fname = (EditText) findViewById(R.id.txtfname);
lname = (EditText) findViewById(R.id.txtlname);
pass = (EditText) findViewById(R.id.txtpass);
inputEmail = (EditText) findViewById(R.id.txtemail);
phone = (EditText) findViewById(R.id.txtphone);
reg = (Button) findViewById(R.id.btnreg);
reg.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final String firstName = fname.getText().toString().trim();
final String lastName = lname.getText().toString().trim();
final String email = inputEmail.getText().toString().trim();
final String password = pass.getText().toString().trim();
final String phoneno = phone.getText().toString().trim();
if (TextUtils.isEmpty(firstName)) {
Toast.makeText(getApplicationContext(), "Enter first name!", Toast.LENGTH_SHORT).show();
return;
}
if (TextUtils.isEmpty(lastName)) {
Toast.makeText(getApplicationContext(), "Enter last name!", Toast.LENGTH_SHORT).show();
return;
}
if (TextUtils.isEmpty(email)) {
Toast.makeText(getApplicationContext(), "Enter email address!", Toast.LENGTH_SHORT).show();
return;
}
if (TextUtils.isEmpty(password)) {
Toast.makeText(getApplicationContext(), "Enter password!", Toast.LENGTH_SHORT).show();
return;
}
if (TextUtils.isEmpty(phoneno)) {
Toast.makeText(getApplicationContext(), "Enter phone number!", Toast.LENGTH_SHORT).show();
return;
}
if (password.length() < 6) {
Toast.makeText(getApplicationContext(), "Password too short, enter minimum 6 characters!", Toast.LENGTH_SHORT).show();
return;
}
if (phoneno.length() < 10) {
Toast.makeText(getApplicationContext(), "Invalid Phone Number!", Toast.LENGTH_SHORT).show();
return;
}
//progressBar.setVisibility(View.VISIBLE);
//create user
auth.createUserWithEmailAndPassword(email, password)
.addOnCompleteListener(SignupActivity.this, new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
Toast.makeText(SignupActivity.this, "createUserWithEmail:onComplete:" + task.isSuccessful(), Toast.LENGTH_SHORT).show();
//progressBar.setVisibility(View.GONE);
// If sign in fails, display a message to the user. If sign in succeeds
// the auth state listener will be notified and logic to handle the
// signed in user can be handled in the listener.
if (!task.isSuccessful()) {
Toast.makeText(SignupActivity.this, "Authentication failed." + task.getException(),
Toast.LENGTH_SHORT).show();
} else {
HashMap<String, Object> map = new HashMap<String, Object>();
final FirebaseUser user = task.getResult().getUser();
map.put("user_id", user.getUid());
map.put("email", email);
map.put("last_connection", Calendar.getInstance(Locale.US).getTimeInMillis());
DatabaseReference userDbRef = FirebaseDatabase.getInstance().getReference().child("user").child(user.getUid());
userDbRef.setValue(map)
.addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
if (task.isSuccessful()) {
// Update the username
UserProfileChangeRequest updateRequest =
new UserProfileChangeRequest.Builder()
.setDisplayName(firstName)
.build();
auth.getCurrentUser().updateProfile(updateRequest).addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
startActivity(new Intent(SignupActivity.this, LoginActivity.class));
finish();
}
});
} else {
//user.delete();
Toast.makeText(SignupActivity.this,
"Could not add the user to the database", Toast.LENGTH_SHORT).show();
}
}
});
}
}
});
}
});
}
}
错误
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.kiit.shoppar, PID: 14665
java.lang.NullPointerException: Attempt to invoke virtual method
'com.google.android.gms.tasks.Task com.google.firebase.auth.FirebaseAuth.createUserWithEmailAndPassword(java.lang.String, java.lang.String)' on a null object reference
at com.example.kiit.shoppar.SignupActivity$1.onClick(SignupActivity.java:90)
at android.view.View.performClick(View.java:6294)
at android.view.View.onKeyUp(View.java:12470)
at android.widget.TextView.onKeyUp(TextView.java:7475)
at android.view.KeyEvent.dispatch(KeyEvent.java:2715)
at android.view.View.dispatchKeyEvent(View.java:11713)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1834)
at com.android.internal.policy.DecorView.superDispatchKeyEvent(DecorView.java:440)
at com.android.internal.policy.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1819)
at android.app.Activity.dispatchKeyEvent(Activity.java:3267)
at android.support.v7.app.AppCompatActivity.dispatchKeyEvent(AppCompatActivity.java:534)
at android.support.v7.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:58)
at android.support.v7.app.AppCompatDelegateImplBase$AppCompatWindowCallbackBase.dispatchKeyEvent(AppCompatDelegateImplBase.java:316)
at com.android.internal.policy.DecorView.dispatchKeyEvent(DecorView.java:354)
at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:4733)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4605)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4147)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4200)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4166)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4293)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4174)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4350)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4147)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4200)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4166)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:4174)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:4147)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:4200)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:4166)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:4326)
at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:4487)
at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:2435)
at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:1998)
at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:1989)
at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:2412)
at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141)
at android.os.MessageQueue.nativePollOnce(Native Method)
at android.os.MessageQueue.next(MessageQueue.java:325)
at android.os.Looper.loop(Looper.java:142)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Application terminated.
您的实例变量auth为空或从未正确分配，您应该先调用auth = FirebaseAuth.getInstance()吗？
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