Android base activity with auto bind controls to class fields, button click to method etc...

BaseActivity.java

package br.com.vendas;

import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

public class BaseActivity extends AppCompatActivity implements View.OnClickListener {

    public static final SimpleDateFormat DATE_FORMAT = new SimpleDateFormat("dd/MM/yyyy");
    public static final DecimalFormat DECIMAL_FORMAT;

    static {
        DecimalFormatSymbols sym = new DecimalFormatSymbols();
        sym.setDecimalSeparator(',');
        DECIMAL_FORMAT = new DecimalFormat("0.00", sym);
    }

    protected final Map<View, String> views = new HashMap<>();

    @Override
    protected void onStart() {
        super.onStart();
        bind(findViewById(android.R.id.content));
    }

    protected void bind(View view) {
        if (view instanceof ViewGroup) {
            ViewGroup group = (ViewGroup)view;
            for (int i = 0; i < group.getChildCount(); i++) {
                bind(group.getChildAt(i));
            }
        }

        if (!(view.getTag() instanceof String))
            return;

        String tag = (String)view.getTag();
        views.put(view, tag);

        // alimenta variaveis com views
        try {
            Field field = getClass().getDeclaredField(tag);
            field.setAccessible(true);
            field.set(this, view);
        } catch (Exception e) {
            e.printStackTrace();
        }

        // bind de btns para metodos da activity
        if (view instanceof Button) {
            Button btn = (Button)view;
            btn.setOnClickListener(this);
            return;
        }
    }

    @Override
    public void onClick(View view) {
        try {
            Method m = getClass().getDeclaredMethod(views.get(view));
            m.setAccessible(true);
            m.invoke(this);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    protected void updateModel(Object obj) {
        iterateViews(obj, false, true);
    }

    protected void refreshView(Object obj) {
        iterateViews(obj, true, false);
    }

    protected void iterateViews(Object obj, boolean refreshView, boolean updateModel) {
        Field[] fields = obj.getClass().getDeclaredFields();
        for (int i = 0; i < fields.length; i++) {
            Field it = fields[i];
            it.setAccessible(true);

            String name = it.getName();
            View view = null;
            for (Map.Entry<View, String> entry: views.entrySet()) {
                if (!entry.getValue().equals(name))
                    continue;

                view = entry.getKey();
                break;
            }

            if (view == null)
                continue;

            try {
                if (refreshView)
                    formatModelValue(name, view, it.get(obj));

                if (updateModel)
                    it.set(obj, parseViewValue(name, it.getType(), view));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    protected Object parseViewValue(String name, Class targetType, View view) throws ParseException {
        if (view instanceof EditText) {
            String str = ((EditText) view).getText() + "";
            if (targetType == Date.class)
                return DATE_FORMAT.parse(str);

            if (targetType == Integer.class)
                return Integer.parseInt("0" + str);

            if (targetType == Long.class)
                return Long.parseLong("0" + str);

            if (targetType == BigDecimal.class)
                return DATE_FORMAT.parse(str);

            return str;
        }

        return null;
    }

    protected void formatModelValue(String name, View view, Object value) {
        if (view instanceof TextView) {
            TextView edit = (TextView) view;
            if (value instanceof String || value instanceof Integer || value instanceof Long)
                edit.setText(value + "");

            if (value instanceof Date)
                edit.setText(new SimpleDateFormat("dd/MM/yyyy").format(value));

            if (value instanceof BigDecimal)
                edit.setText(DECIMAL_FORMAT.format(value));

            return;
        }
    }
}