DDM20201110

package com.joythis.android.distancebetweendates;

public class AmCalendar {
    public int distanceInDaysTo(
        AmCalendar pSomeOtherCalendar
    ){
        return 0;
    }//distanceInDaysTo

    public static boolean validYear(int pY){
        return pY>=1;
    }//validYear

    public static boolean validMonth(int pM){
        return pM>=1 && pM<=12;
    }//validMonth

    public static boolean validDay(
        int pY,
        int pM,
        int pD
    ){
        return pD>=1 && pD<=AmCalendar.daysInMonth(pY, pM);
    }//validDay

    public final static int IMPOSSIBLE_MONTH = -1;
    public static int daysInMonth (
        int pY,
        int pM
    ){
        switch(pM){
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12:
                return 31;
            case 4:
            case 6:
            case 9:
            case 11:
                return 30;
            case 2:
                return AmCalendar.leapYear(pY) ? 29 : 28;
            default:
                return IMPOSSIBLE_MONTH;
        }//switch
    }//daysInMonth

    public static boolean leapYear(
        int pY
    ){
        boolean bM400 = pY%400 == 0;
        boolean bM100 = pY%100 == 0;
        boolean bM4 = pY%4 == 0;

        boolean bCase1 = bM400; //2000
        boolean bCase2 = bM4 && !bM100; //1996

        return bCase1 || bCase2;
    }//leapYear
}//AmCalendar

//**
package com.joythis.android.distancebetweendates;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
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 mNpYear, mNpMonth, mNpDay;
    Button mBtnConfirmDate;
    ListView mLvFeedback;

    ArrayList<String> mAlUserMsgs;
    ArrayAdapter<String> mAd;

    Button.OnClickListener mButtonClickHandler =
        new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                actionSendDateToOtherActivity();
            }//onClick
        };//mButtonClickHandler

    NumberPicker.OnValueChangeListener mNumberPickerChangeHandler =
    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);

            //some of the code that follows became
            //unnecessary, because of this line
            mNpDay.setMaxValue(
                AmCalendar.daysInMonth(y,m)
            );

            if (!bValidDate){
                //%1$d-%2$d-%3$d invalid date!
                String strMsg =
                    getResources().getString(
                        R.string.strInvalidDate,
                        y,m,d
                    );

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

                //TODO
                int iMaxDaysForSelectedYM =
                    AmCalendar.daysInMonth(y, m);

                /*
<string name="strInvalidDate">%1$d-%2$d-%3$d invalid date!</string>
<string name="strDayFixed">Day fixed from %1$d to %2$d.</string>
                 */
                mNpDay.setValue(iMaxDaysForSelectedYM);
                mNpDay.setMaxValue(iMaxDaysForSelectedYM);

                strMsg = getString(
                    R.string.strDayFixed,
                    d,
                    iMaxDaysForSelectedYM
                );
                mAlUserMsgs.add(0, strMsg);
                mAd.notifyDataSetChanged();
            }//if
        }//onValueChange
    };//mNumberChangeHandler

    /*
    single purpose:
    - exemplify how to navigate from this activity to A2
     */
    public static String KEY_HELLO = "KEY_HELLO";
    public static String KEY_THE_USER_DATE = "KEY_THE_USER_DATE";
    public static String KEY_YEAR = "KEY_YEAR";
    public static String KEY_MONTH = "KEY_MONTH";
    public static String KEY_DAY = "KEY_DAY";
    public static String KEY_BUNDLE = "KEY_BUNDLE";
    void actionSendDateToOtherActivity(){
        Intent intentForSimpleNavigationToA2 = new Intent(
            //this,
            DateInputActivity.this, //source intance
            A2.class//class of destination
        );

        //send "hello" to the other Activity?
        String strToSend = "hello";
        intentForSimpleNavigationToA2.putExtra(
            KEY_HELLO,
            strToSend
        );

        int y, m, d;
        y=mNpYear.getValue();
        m=mNpMonth.getValue();
        d=mNpDay.getValue();
        //<string name="strYMD">%1$d-%2$d-%3$d</string>
        String strTheUserDate =
            getString(
                R.string.strYMD,
                y,
                m,
                d
            );
        intentForSimpleNavigationToA2.putExtra(
            KEY_THE_USER_DATE,
            strTheUserDate
        );

        intentForSimpleNavigationToA2.putExtra(
            KEY_YEAR, y
        );
        intentForSimpleNavigationToA2.putExtra(
            KEY_MONTH,
            m
        );
        intentForSimpleNavigationToA2.putExtra(
            KEY_DAY,
            d
        );

        //4th and final variant of sending data to another Activity
        Bundle b = new Bundle();
        b.putInt(KEY_YEAR, y);
        b.putInt(KEY_MONTH, m);
        b.putInt(KEY_DAY, d);
        intentForSimpleNavigationToA2.putExtra(
            KEY_BUNDLE,
            b
        );

        //we are <del>NOT</del> sending the user selected date
        startActivity(
            intentForSimpleNavigationToA2
        );


    }//actionSendDateToOtherActivity

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

        init();
    }//onCreate

    void init(){
        mContext = DateInputActivity.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);

        NumberPicker[] aNpYMD = {
            mNpYear, mNpMonth, mNpDay
        };
        for (NumberPicker np : aNpYMD)
            np.setOnValueChangedListener(mNumberPickerChangeHandler);

        //TODO
        Calendar cal = Calendar.getInstance();
        mNpYear.setMinValue(1);
        mNpYear.setMaxValue(9999);
        mNpYear.setValue(
            //2020
            /*
            Calendar.getInstance().get(
                Calendar.YEAR
            )
             */
            cal.get(Calendar.YEAR)
        );

        mNpMonth.setMinValue(1);
        mNpMonth.setMaxValue(12);
        mNpMonth.setValue(
            //11
            /*
            Calendar.getInstance().get(
                Calendar.MONTH
            )
             */
            cal.get(
                Calendar.MONTH
            )+1
        );

        mNpDay.setMinValue(1);
        mNpDay.setMaxValue(31);
        mNpDay.setValue(
            //10
            cal.get(Calendar.DAY_OF_MONTH)
        );

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

        mBtnConfirmDate.setOnClickListener(
            mButtonClickHandler
        );package com.joythis.android.distancebetweendates;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;

import java.util.Calendar;
import java.util.Date;

public class A2 extends AppCompatActivity {

    TextView mTv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_a2);

        init();
    }//onCreate

    void init(){
        mTv = findViewById(R.id.idTv);

        receiveAndShowSentData();
    }//init

    void receiveAndShowSentData(){
        //pattern to receive data sent from another activity?
        Intent whoCalledMe = getIntent();
        if (whoCalledMe!=null){
            String strThisWasSentToMe =
                whoCalledMe.getStringExtra(
                    DateInputActivity.KEY_HELLO
                );

            String strTheUserDate =
                whoCalledMe.getStringExtra(
                    DateInputActivity.KEY_THE_USER_DATE
                );

            int y, m, d;
            y = whoCalledMe.getIntExtra(
                    DateInputActivity.KEY_YEAR,
                    Calendar.getInstance().get(Calendar.YEAR) //default value, in case there is no value in the key
                );
            m = whoCalledMe.getIntExtra(
                    DateInputActivity.KEY_MONTH,
                    Calendar.getInstance().get(Calendar.MONTH) //default value, in case there is no value in the key
            );
            d = whoCalledMe.getIntExtra(
                    DateInputActivity.KEY_DAY,
                    Calendar.getInstance().get(Calendar.DAY_OF_MONTH) //default value
            );

            //4th alt
            Bundle b = whoCalledMe.getBundleExtra(
                DateInputActivity.KEY_BUNDLE
            );
            int yy =
                b.containsKey(DateInputActivity.KEY_YEAR)?
                b.getInt(DateInputActivity.KEY_YEAR)
                :
                Calendar.getInstance().get(Calendar.YEAR);
            int mm =
                b.containsKey(DateInputActivity.KEY_MONTH)?
                b.getInt(DateInputActivity.KEY_MONTH)
                :
                Calendar.getInstance().get(Calendar.MONTH);
            int dd =
                b.containsKey(DateInputActivity.KEY_DAY)?
                b.getInt(DateInputActivity.KEY_DAY)
                :
                Calendar.getInstance().get(Calendar.DAY_OF_MONTH);



            mTv.setText(
                strThisWasSentToMe+
                "\n"+
                strTheUserDate+
                "\n"+
                "y="+String.valueOf(y)+
                "\n"+
                "m="+String.valueOf(m)+
                "\n"+
                "d="+String.valueOf(d)+

                "\n"+
                "yy="+String.valueOf(yy)+
                "\n"+
                "mm="+String.valueOf(mm)+
                "\n"+
                "dd="+String.valueOf(dd)

            );
        }//if
    }//receiveAndShowSentData
}//A2
    }//init
}
//*