[Android Studio] ex) Webview

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.graphics.Color;
import android.os.Bundle;
import android.os.SystemClock;
import android.view.View;
import android.widget.Chronometer;
import android.widget.DatePicker;
import android.widget.RadioButton;
import android.widget.TextView;
import android.widget.TimePicker;

public class MainActivity extends AppCompatActivity {

    Chronometer chrono;
    RadioButton rdoCal, rdoTime;
    DatePicker dPiker;
    TimePicker tPicker;
    TextView tvYear, tvMonth, tvday, tvHour, tvMinute;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main1);

        setTitle("시간예약");
        //chronometer
        chrono = (Chronometer) findViewById(R.id.chronometer1);
        //rdoCal 2
        rdoCal = (RadioButton) findViewById(R.id.rdoCal);
        rdoTime = (RadioButton) findViewById(R.id.rdoTime);
        //frameL 2 widget
        dPiker = (DatePicker) findViewById(R.id.cPicker);
        tPicker = (TimePicker) findViewById(R.id.tPicker);
        //ymdht
        //tvYear = (TextView) findViewById(R.id.tv)

        //hide 2
        rdoCal.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                tPicker.setVisibility(view.INVISIBLE);
                dPiker.setVisibility(view.VISIBLE);
            }
        });
        rdoTime.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                tPicker.setVisibility(view.VISIBLE);
                dPiker.setVisibility(view.INVISIBLE);
            }
        });
        //chrono click timer on
        chrono.setTextColor(new View.OnLongClickListener() {
            public boolean onClicker(View view) {
                chrono.setBase(SystemClock.elapsedRealtime());
                chrono.start();
                chrono.setTextColor(Color.RED);
                rdoCal.setVisibility(view.VISIBLE);
                rdoTime.setVisibility(view.VISIBLE);
            }
        });
        //chrono longclick timer stop
        tvYear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                chrono.stop();
                chrono.setTextColor(Color.BLUE);

                tvYear.setText(Integer.toString(dPiker.getYear()));
                tvMonth.setText(Integer.toString(1 + dPiker.getMonth()));
                tvday.setText(Integer.toString(dPiker.setDayOfMonth()));

                tvHour.setText((Integer.toString(tPicker.getCurrentHour())));
                tvMinute.setText(Integer.toString(tPicker.getCurrentMinute()));

                rdoCal.setVisibility(view.VISIBLE);
                rdoTime.setVisibility(view.VISIBLE);
                tPicker.setVisibility(view.VISIBLE);
                dPiker.setVisibility(view.VISIBLE);
                return false;
            }
        });
        }
    }
}