Question

我想启动我的新的也是第一个应用程序，并且每当我按下登录按钮时它就会崩溃。它告诉我，存在NullPointerException，但我不知道为什么。有人可以帮我吗？一直在寻找解决方案，但到目前为止找不到任何帮助的解决方案。

package com.glowchat.app;

import android.support.annotation.NonNull;
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.TextView;
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;

public class LoginActivity extends AppCompatActivity {

    private Button loginbtn;
    private EditText email;
    private EditText password;

    private FirebaseAuth auth;
    private FirebaseUser user;

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

        loginbtn = (Button) findViewById(R.id.loginbtn);

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

                email = (EditText) findViewById(R.id.inputEmailLogin);
                password = (EditText) findViewById(R.id.inputPasswordLogin);

                String loginemail = email.getText().toString();
                String loginpassword = password.getText().toString();

                if (loginemail.isEmpty() || loginpassword.isEmpty()) {
                    Toast.makeText(LoginActivity.this, "Please fill out all fields.", Toast.LENGTH_SHORT).show();
                } else {
                    auth.signInWithEmailAndPassword(loginemail, loginpassword).addOnCompleteListener(LoginActivity.this, new OnCompleteListener<AuthResult>() {
                        @Override
                        public void onComplete(@NonNull Task<AuthResult> task) {
                            if (task.isSuccessful()) {
                                Toast.makeText(LoginActivity.this, "Authentication successfull.", Toast.LENGTH_SHORT).show();
                                user = auth.getCurrentUser();
                            } else {
                                Toast.makeText(LoginActivity.this, "Authentication failed. Check your input and your internet connection.", Toast.LENGTH_SHORT).show();
                                user = null;
                            }
                        }
                    });
                }
            }
            });
    }

}

这是我在“运行”选项卡中得到的：

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.glowchat.app, PID: 29274
    java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.tasks.Task com.google.firebase.auth.FirebaseAuth.signInWithEmailAndPassword(java.lang.String, java.lang.String)' on a null object reference
        at com.glowchat.app.LoginActivity$1.onClick(LoginActivity.java:47)
        at android.view.View.performClick(View.java:6935)
        at android.widget.TextView.performClick(TextView.java:12742)
        at android.view.View$PerformClick.run(View.java:26211)
        at android.os.Handler.handleCallback(Handler.java:790)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:7000)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:441)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)

Answer 1

您刚刚声明了FirebaseAuth身份验证，但未对其进行初始化，因此您无法 signInWithEmailAndPassword 。

我认为这个Firebase docs会对您有所帮助。

signInWithEmailAndPassword。获取一个NullPointerException

1 个答案: