DDM20211019

package com.joythis.android.fourcorners;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log; //for statements like Log.e(...)
import android.view.View; //for the View datatype
import android.widget.Button; //here via ALT+ENTER
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    //ALT+ENTER > "import class" > import android.widget.Button;
    //Class data members
    Button mBtnULC=null, mBtnURC=null, mBtnLLC=null, mBtnLRC=null; //cascade declaration

    public static final String ERROR_STAMP = "NULL OBJECT";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.activity_main);
        //CTRL+SPACE - all available autocomplete options
        setContentView(R.layout.rl_four_corners_v2);

        init();
    }//onCreate

    public void someMethodInTheActivityClass (View pV){
        Toast t = Toast.makeText(
            this,
            "hello",
            Toast.LENGTH_LONG
        );
        t.show();
    }//someMethodInTheActivityClass

    void init(){
        //1 - bindings between XML elements and class data members
        //get rid of the null status
        mBtnULC = findViewById(R.id.idBtnULC);
        mBtnLRC = findViewById(R.id.idBtnLRC);
        mBtnLLC = findViewById(R.id.idBtnLLC);
        mBtnLRC = findViewById(R.id.idBtnLRC);

        //quality control
        Button[] aRelevantButtons = {
            mBtnLLC, mBtnLRC, mBtnLLC, mBtnLRC
        };
        for (Button b : aRelevantButtons){
            boolean bNull = b==null;
            if (bNull){
                Log.e(
                    ERROR_STAMP,
                    "Button found null. Aborting."
                );
                finish(); //terminates the Activity
            }//if
        }//for

        //2 - via the Java bindings, assign behavior to the XML elements
    }//init
}//MainActivity