'Trying to connect to Firebase but crashes when adding button

I'm trying to set an app to just enter something on the textEdit and change it in real time in the Firebase database. The app works just fine if I just do myRef = database.getReference(""); but when I try to add the editing feature it just crashes the app.

This is the code:

package com.example.usuario.firebase;

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 com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

public class MainActivity extends AppCompatActivity {
    FirebaseDatabase database = FirebaseDatabase.getInstance();
    DatabaseReference myRef = database.getReference("message");

    Button enviar = (Button) findViewById(R.id.button2);
    EditText editar = (EditText)findViewById(R.id.editText);
    TextView ver = (TextView) findViewById(R.id.textView);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myRef.setValue("test");

        enviar.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                myRef.setValue(editar.getText().toString());
            }
        });
    }
}

Error:

java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.usuario.firebase/com.example.usuario.firebase.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2626)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2785)
    at android.app.ActivityThread.-wrap12(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1532)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:163)
    at android.app.ActivityThread.main(ActivityThread.java:6326)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:880)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:770)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
    at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:117)
    at android.support.v7.app.AppCompatDelegateImplV9.<init>(AppCompatDelegateImplV9.java:149)
    at android.support.v7.app.AppCompatDelegateImplV11.<init>(AppCompatDelegateImplV11.java:29)
    at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:54)
    at android.support.v7.app.AppCompatDelegateImplV23.<init>(AppCompatDelegateImplV23.java:31)
    at android.support.v7.app.AppCompatDelegateImplN.<init>(AppCompatDelegateImplN.java:31)
    at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:198)
    at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:183)
    at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:519)
    at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:190)
    at com.example.usuario.firebase.MainActivity.<init>(MainActivity.java:18)
    at java.lang.Class.newInstance(Native Method)
    at android.app.Instrumentation.newActivity(Instrumentation.java:1079)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2616)
    ... 9 more
javaandroid


Solution 1:[1]

package com.example.usuario.firebase;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    FirebaseDatabase database = FirebaseDatabase.getInstance();
    DatabaseReference myRef = database.getReference("message");

    Button enviar = (Button) findViewById(R.id.button2);
    EditText editar = (EditText)findViewById(R.id.editText);
    TextView ver = (TextView) findViewById(R.id.textView);
        myRef.setValue("test");

        enviar.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                myRef.setValue(editar.getText().toString());
            }
        });
    }
}

Solution 2:[2]

First remove this myRef.setValue("test"); And replace this myRef.setValue(editar.getText().toString()); with this myRef.child("test").setValue(editar.getText().toString());.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Meet Bhavsar
Solution 2 MAMO EMIRU

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