코드는 다 맞는 것 같은데 왜 안 될까요? 아래에 코드 첨부할테니 혹여 제가 놓친 것이 있다면 말씀해주시면 감사하겠습니다 감사합니다

MainActivity.java

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.content.ClipboardManager; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Bundle; import android.view.View; import android.widget.ArrayAdapter; import android.widget.Button; import android.widget.EditText; import android.widget.ImageView; import android.widget.ListView; import android.widget.TextView; import android.widget.Toast;

import com.google.firebase.database.ChildEventListener; import com.google.firebase.database.DataSnapshot; import com.google.firebase.database.DatabaseError; import com.google.firebase.database.DatabaseReference; import com.google.firebase.database.FirebaseDatabase; import com.google.firebase.database.ValueEventListener;

import java.io.InputStream; import java.text.CollationElementIterator;

public class MainActivity extends AppCompatActivity { Button button1; EditText edittext1; TextView textview1 = (TextView)findViewById(R.id.textview1);

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    FirebaseDatabase database = FirebaseDatabase.getInstance();
    DatabaseReference myRef = database.getReference("message");

    myRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            // This method is called once with the initial value and again
            // whenever data at this location is updated.
            String value = dataSnapshot.getValue(String.class);
            textview1.setText(value);   //데이터베이스 값
        }

        @Override
        public void onCancelled(DatabaseError error) {
            // Failed to read value
        }
    });
}

public void click1button(View v){
    FirebaseDatabase database = FirebaseDatabase.getInstance();
    DatabaseReference myRef = database.getReference("message");
    myRef.child("message").push().setValue(edittext1.getText().toString());
}

}

activity_main.xml

<EditText
    android:id="@+id/edittext1"
    android:layout_width="391dp"
    android:layout_height="144dp"
    android:ems="10"
    android:inputType="textPersonName"
    android:text="내용" />


<Button
    android:id="@+id/button1"
    android:layout_width="204dp"
    android:layout_height="100dp"
    android:onClick="click1button"
    android:text="확인(임시저장기능)" />

<TextView
    android:id="@+id/textview1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="데이터베이스 확인영역" />

xml 화면입니다.