Android: "Piedra, papel y tijeras"

Aquí dando mis primeros gateos en el mundo de desarrollo de Android. En esta simple aplicación ejemplifico el uso de:

• Buttons
• Click events
• Image Views
• Alert dialogs

La aplicación es un simple juego de"Piedra, Papel y Tijeras". El usuario hace la selección entre las clásicas tres opciones, y luego Android hace una selección aleatoria. De acuerdo a las básicas reglas universales de este conocido juego, el resultado es determinado y mostrado en un mensaje de alerta.

Este es el layout básico del juego. Las dos imágenes de signo de interrogación son para desplegar las dos selecciones. Las otras tres imágenes son para que el usuario haga la selección.

XML del layout:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20dp"
        android:padding="@dimen/padding_medium"
        android:text="Rock, Paper, Scissors!"
        tools:context=".RockPaperScissors" />

    <Button
        android:id="@+id/buttonRock"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="147dp"
        android:layout_marginRight="20dp"
        android:layout_toLeftOf="@+id/textView1"
        android:background="@drawable/rock_small" />

    <Button
        android:id="@+id/buttonPaper"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/buttonRock"
        android:layout_alignBottom="@+id/buttonRock"
        android:layout_centerHorizontal="true"
        android:background="@drawable/paper_small" />

    <Button
        android:id="@+id/buttonScissors"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/buttonPaper"
        android:layout_alignBottom="@+id/buttonPaper"
        android:layout_marginLeft="23dp"
        android:layout_toRightOf="@+id/textView1"
        android:background="@drawable/scissors_small" />

    <ImageView
        android:id="@+id/imageViewAnswerUser"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView1"
        android:layout_marginTop="26dp"
        android:layout_toLeftOf="@+id/buttonPaper"
        android:src="@drawable/question" />

    <ImageView
        android:id="@+id/ImageViewAnswerAndroid"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/buttonScissors"
        android:layout_alignTop="@+id/imageViewAnswerUser"
        android:src="@drawable/question" />

    <ImageButton
        android:id="@+id/imageButtonHome"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/buttonPaper"
        android:layout_below="@+id/buttonPaper"
        android:layout_marginTop="38dp"
        android:src="@drawable/home" />

</RelativeLayout>

código de la actividad:

package com.example.mytoolbox;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ImageView;

public class RockPaperScissors extends Activity implements OnClickListener {
 
 public enum Option {
  ROCK, PAPER, SCISSORS
 }
 
 public enum Result {
  WIN, LOSS, DRAW  
 }
 
 private Option userSelection;
 private Result gameResult;
 

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_rock_paper_scissors);
        
        Button buttonRock = (Button) findViewById(R.id.buttonRock);
        Button buttonpaper = (Button) findViewById(R.id.buttonPaper);
        Button buttonScissors = (Button) findViewById(R.id.buttonScissors);
        ImageButton buttonHome = (ImageButton) findViewById(R.id.imageButtonHome);
        
        // Set click listening event for all buttons.
        buttonRock.setOnClickListener(this);
        buttonpaper.setOnClickListener(this);
        buttonScissors.setOnClickListener(this);
        buttonHome.setOnClickListener(this);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_rock_paper_scissors, menu);
        return true;
    }

 @Override
 public void onClick(View v) {
  
  ImageView imageView = (ImageView) findViewById(R.id.imageViewAnswerUser);
  boolean play = true;
  
  switch (v.getId()) {
   case R.id.buttonRock:
    userSelection = Option.ROCK;
    imageView.setImageResource(R.drawable.rock);
    break; 
   case R.id.buttonPaper:
    userSelection = Option.PAPER;
    imageView.setImageResource(R.drawable.paper);
    break;
   case R.id.buttonScissors:
    userSelection = Option.SCISSORS;
    imageView.setImageResource(R.drawable.scissors);
    break;
   case R.id.imageButtonHome:
    startActivity(new Intent(RockPaperScissors.this, ChooseActivity.class)); // To go home.
    play = false;
    break;
  }
  
  if(play) {
   play();
   showResults();
  }
 }

 private void showResults() {
  AlertDialog.Builder builder = new AlertDialog.Builder(RockPaperScissors.this);     
     builder.setCancelable(false);     
     builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {   
   @Override
   public void onClick(DialogInterface dialog, int which) {
    // Do nothing   
   }
  });
     
     // Sets the right message according to result.
     if(gameResult == Result.LOSS) {
      builder.setMessage("You Loose!");
     } else if(gameResult == Result.WIN) {
      builder.setMessage("You Win!");
     } else if(gameResult == Result.DRAW) {
      builder.setMessage("It's a draw!");
     } 
     
     AlertDialog alert = builder.create();
     alert.show();  
    } 

 private void play() {
  // Generates a random play.
  int rand =  ((int)(Math.random() * 10)) % 3;
  Option androidSelection = null;
  ImageView imageView = (ImageView) findViewById(R.id.ImageViewAnswerAndroid);
  
  // Sets the right image according to random selection.
  switch (rand) {
   case 0:
    androidSelection = Option.ROCK;
    imageView.setImageResource(R.drawable.rock);
    break;
   case 1:
    androidSelection = Option.PAPER;
    imageView.setImageResource(R.drawable.paper);
    break;
   case 2:
    androidSelection = Option.SCISSORS;
    imageView.setImageResource(R.drawable.scissors);
    break;
  }
  // Determine game result according to user selection and Android selection.
  if(androidSelection == userSelection) {
   gameResult = Result.DRAW;
  }
  else if(androidSelection == Option.ROCK && userSelection == Option.SCISSORS) {
   gameResult = Result.LOSS;
  }
  else if(androidSelection == Option.PAPER && userSelection == Option.ROCK) {
   gameResult = Result.LOSS;
  } 
  else if(androidSelection == Option.SCISSORS && userSelection == Option.PAPER) {
   gameResult = Result.LOSS;
  } else {
   gameResult = Result.WIN;
  }  
 }    
}

App corriendo: