DDM 2022-10-19

<?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">

    <Button
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:id="@+id/idBtnCSE"
        android:text="@string/strBtnCSE"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <Button
        android:layout_alignParentTop="true"
        android:layout_alignParentRight="true"
        android:id="@+id/idBtnCSD"
        android:text="@string/strBtnCSD"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <Button
        android:layout_alignParentLeft="true"
        android:layout_alignParentBottom="true"
        android:id="@+id/idBtnCIE"
        android:text="@string/strBtnCIE"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <Button
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:id="@+id/idBtnCID"
        android:text="@string/strBtnCID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
</RelativeLayout>
********************************
package com.joythis.android.fourcorners;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity
    extends AppCompatActivity // class inheritance
    implements View.OnClickListener // interface assumption
{
    AmUtil mUtil; // cliente de AmUtil

    public final static String STAMP = "@MainActivity";

    /*
    Todos os elementos de layout que sejam relevantes para a
    programação (para comportamento) têm que ter um id no Layout
    e devem ter um data member correspondente na class da Activity
    que carregar o Layout
     */
    Button mBtnCSE; //null
    Button mBtnCSD; //null
    Button mBtnCIE; //null
    Button mBtnCID; //null

    Context mContext; //null

    // tipo nome
    Button.OnClickListener mBtnClickHandler =
        new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Button btnWasClicked = (Button)v;
                int id = v.getId();

                String strMsg = "Hello via mBtnClickHandler from ";
                switch(id){
                    case R.id.idBtnCSE:
                        strMsg += strMsg.format("CSE");
                        break;
                    case R.id.idBtnCSD:
                        strMsg += strMsg.format("CSD");
                        break;
                    case R.id.idBtnCIE:
                        strMsg += strMsg.format(
                            btnWasClicked.getText().toString()
                        );
                        break;
                    case R.id.idBtnCID:
                        strMsg += strMsg.format(
                            btnWasClicked.getText().toString()
                        );
                        break;
                } // switch
                mUtil.fb(strMsg);
                /*
                AmUtil.fbs(
                    this, // this NÃO É a Activity
                    strMsg
                );
                 */
            } // onClick
        }; //mBtnClickHandler

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // setContentView(R.layout.activity_main);
        setContentView(R.layout.ll_four_corners_v1);

        init();
    } // onCreate

    void init(){
        // inicializações dos data members
        mUtil = new AmUtil(this);

        mContext = this;
        mBtnCSE = findViewById(R.id.idBtnCSE);
        mBtnCSD = findViewById(R.id.idBtnCSD);
        mBtnCIE = findViewById(R.id.idBtnCIE);
        mBtnCID = findViewById(R.id.idBtnCID);

        // controlo de qualidade
        Object[] theRelevant = {
            mContext,
            mBtnCSE,
            mBtnCSD,
            mBtnCIE,
            mBtnCID
        };
        boolean bFoundANull = false;
        for (Object r : theRelevant){
            bFoundANull = r==null;
            if (bFoundANull){
                // mensagem
                Log.e(
                    STAMP,
                    "There is 1+ null relevant objects. Aborting."
                );
                this.finish();
                return;
            }
        } // for

        // conferir comportamentos
        Button[] buttonsWithSharedBehavior = {
            //mBtnCSE, mBtnCSD, mBtnCIE, mBtnCID
            //mBtnCSE - comporta-se via onClick do XML
            mBtnCSD, mBtnCIE
            // mBtnCID - comporta-se via onClick da class
        };
        /*
        mBtnCSE.setOnClickListener(mBtnClickHandler);
        mBtnCID.setOnClickListener(mBtnClickHandler);
        */
        for (Button b : buttonsWithSharedBehavior)
            b.setOnClickListener
                (
                    //this
                    mBtnClickHandler
                );

        mBtnCID.setOnClickListener(this);
    } // init

    public void responderAoClick(View pV){
        Toast t = Toast.makeText(
            this,
            "Responding to onClick as set in XML\n"+
            getResources().getString(R.string.strBtnCSE),
            Toast.LENGTH_SHORT
        );
        t.setGravity(
            Gravity.CENTER,
            0,
            0
        );
        t.show();
    } // responderAoClick

    @Override
    public void onClick(View v) {
        mUtil.fb(
        "handling via class implements\n"+
            ((Button)v).getText().toString()
        );
    } //onClick
} // class MainActivity