Pasted

package com.example.murilo.exercicio_erro_inicializacao_java_ecm251;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import com.example.murilo.exercicio_erro_inicializacao_java_ecm251.R;
 
public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TextView tv;
        tv.setText("Ola Mundo!");
    }
    public void clicado(View view) {
        EditText etNome = (EditText) findViewById(R.id.etNome);
        TextView tvDados = (TextView) findViewById(R.id.tvTexto);
        tvDados.setText(etNome.getText().toString() + " bem vindo!");
    }
}