PDM2 20201110

package com.joythis.android.distancebetweendates;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.NumberPicker;

import java.util.ArrayList;
import java.util.Calendar;

public class DateInputActivity extends AppCompatActivity {
    Context mContext;

    NumberPicker.OnValueChangeListener mNpValueChangedHandler =
new NumberPicker.OnValueChangeListener() {
    @Override
    public void onValueChange
    (NumberPicker picker, int oldVal, int newVal) {
        int y = mNpYear.getValue();
        int m = mNpMonth.getValue();
        int d = mNpDay.getValue();

        boolean bValidDate = AmCalendar.validDay(y,m,d);

        int iMaxDayForMonth = AmCalendar.
                numberOfDaysInMonth(y,m);

        mNpDay.setMaxValue(iMaxDayForMonth);

        String strMsg = "";
        if (d>iMaxDayForMonth){
            strMsg = getString(
                    R.string.strFixedDay,
                    d,
                    iMaxDayForMonth
            );
            mUserMsgs.add(0, strMsg);
        }

        if (!bValidDate){
            strMsg = getResources().getString(
                R.string.strInvalidDate,
                y,m,d
           );
            mUserMsgs.add(0, strMsg);

           mNpDay.setValue(iMaxDayForMonth);
           //mNpDay.setMaxValue(iMaxDayForMonth);

           mAd.notifyDataSetChanged();
        }//
    }//onValueChange
};

    NumberPicker mNpYear, mNpMonth, mNpDay;
    Button mBtnConfirmDate;

    ListView mLvFeedback;
    ArrayList<String> mUserMsgs;
    ArrayAdapter<String> mAd;

    Object[] maRelevant;

    Button.OnClickListener mBtnClickHandler =
        new Button.OnClickListener() {
            @Override
            public void onClick(View v) {
                int iYear = mNpYear.getValue();
                int iMonth = mNpMonth.getValue();
                int iDay = mNpDay.getValue();

                String strMsg =
                    getResources().getString(
                        R.string.strUserDate,
                        iYear,
                        iMonth,
                        iDay
                    );

                mUserMsgs.add(0, strMsg);
                mAd.notifyDataSetChanged();

                Intent responseForCallers = new Intent();
                responseForCallers.putExtra(
                    KEY_DATE,
                    strMsg
                );
                setResult(
                    RESULT_OK,
                    responseForCallers
                );
                finish();
            }//onClick
        };

    public final static String KEY_DATE = "KEY_DATE";

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

        init();
    }//onCreate

    Object[] getImportant(){
        Object[] aRelevant = {
            mNpYear,
            mNpMonth,
            mNpDay,
            mBtnConfirmDate,
            mLvFeedback
        };
        return aRelevant;
    }//getImportant

    void init(){
        mContext = this;

        mNpYear = findViewById(R.id.idNpYear);
        mNpMonth = findViewById(R.id.idNpMonth);
        mNpDay = findViewById(R.id.idNpDay);

        mBtnConfirmDate = findViewById(R.id.idBtnConfirmDate);
        mLvFeedback = findViewById(R.id.idLvFeedback);

        maRelevant = this.getImportant();
        boolean bAllAreOK = true;
        for (Object o : maRelevant){
            boolean bOK = o != null;
            bAllAreOK = bAllAreOK && bOK;
        }//for
        if (!bAllAreOK){
            Log.e(
                "@"+getClass().getName(),
                "1+ object(s) are null"
            );
            finish();
            return;
        }//if

        mNpYear.setMinValue(1);
        mNpYear.setMaxValue(9999);
        mNpYear.setValue(Calendar.getInstance().get(Calendar.YEAR));

        mNpMonth.setMinValue(1);
        mNpMonth.setMaxValue(12);
        mNpMonth.setValue(Calendar.getInstance().get(Calendar.MONTH)+1);

        mNpDay.setMinValue(1);
        mNpDay.setMaxValue(31); //TODO
        mNpDay.setValue(
            Calendar.getInstance().
            get(Calendar.DAY_OF_MONTH)
        );

        mUserMsgs = new ArrayList<>();
        mAd = new ArrayAdapter<>(
            mContext,
            android.R.layout.simple_list_item_1,
            mUserMsgs
        );
        mLvFeedback.setAdapter(mAd);

        mBtnConfirmDate.setOnClickListener(
            mBtnClickHandler
        );

        //assigned the onChangeChangeListener to all the NumberPickers
        NumberPicker[] aTrio = {mNpYear, mNpMonth, mNpDay};
        for (NumberPicker np : aTrio) np.
                setOnValueChangedListener(mNpValueChangedHandler);
    }//init
}

//**

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:id="@+id/idLlDatesRequester"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <Button
            android:id="@+id/idBtnRequestDate1"
            android:text="@string/strBtnRequestDate1"
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
        <Button
            android:id="@+id/idBtnRequestDate2"
            android:text="@string/strBtnRequestDate2"
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:id="@+id/idLlInfoRecvDates"
        android:layout_below="@id/idLlDatesRequester"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:id="@+id/idTvDate1"
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
        <TextView
            android:id="@+id/idTvDate2"
            android:layout_weight="1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </LinearLayout>

    <Button
        android:id="@+id/idBtnComputeDistance"
        android:text="@string/strBtnComputeDistance"
        android:layout_below="@id/idLlInfoRecvDates"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

    <ListView
        android:layout_below="@id/idBtnComputeDistance"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</RelativeLayout>