Mini game for android

Question

For Android in this mini game the monkey catches nice bananas and coconuts.

enter image description here

It was somewhat more problematic to create the layout in XML compared to the small game engine and controls.

Maybe we can rewrite the code more object-oriented because it is rather procedural at this time. The game is open for testing in an open alpha and the source is available at my github.

Main activity

package dev.android.jamie;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.view.MotionEventCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.Window;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import java.util.Random;
public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
 public void onItemSelected(AdapterView<?> parent, View view,
 int pos, long id) {
 // An item was selected. You can retrieve the selected item using
 Log.d("myTag", "This is my message" + parent.getItemAtPosition(pos));
 String name = "Jamie";
 String str = parent.getItemAtPosition(pos).toString();
 if (str.equals("Rookie")) {
 cg = new CatchGame(this, 3, name, onScoreListener);
 // setContentView(cg);
 mainLayout.addView(cg);
 getSupportActionBar().hide();
 setContentView(mainLayout);
 Log.d("game", "Started Rookie game");
 } else if (str.equals("Advanced")) {
 mainLayout = new LinearLayout(this);
 mainLayout.setOrientation(LinearLayout.VERTICAL);
 LinearLayout menuLayout = new LinearLayout(this);
 menuLayout.setBackgroundColor(Color.parseColor("#FFFFFF"));
 textView = new TextView(this);
 textView.setVisibility(View.VISIBLE);
 str = "Score: 0";
 textView.setText(str);
 menuLayout.addView(textView);
 Button button = new Button(this);
 button.setText("Pause");
 button.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View v) {
 togglePausePlay();
 }
 });
 menuLayout.addView(button);
 Spinner spinner2 = new Spinner(this);
 spinner2.setOnItemSelectedListener(this);
 ArrayAdapter<String> adapter = new ArrayAdapter<>(MainActivity.this, android.R.layout.simple_list_item_1, spinnerValue);
 spinner2.setAdapter(adapter);
 menuLayout.addView(spinner2);
 mainLayout.addView(menuLayout);
 cg = new CatchGame(this, 5, "Jamie", onScoreListener);
 cg.setBackground(getResources().getDrawable(R.drawable.bg_land_mdpi));
 mainLayout.addView(cg);
// getWindow().requestFeature(Window.FEATURE_ACTION_BAR);
 getSupportActionBar().hide();
 setContentView(mainLayout);
 Log.d("game", "Started Advanced game");
 } else if (str.equals("Expert")) {
 cg = new CatchGame(this, 7, name, onScoreListener);
 //setContentView(cg);
 mainLayout.addView(cg);
 getSupportActionBar().hide();
 setContentView(mainLayout);
 }
 }
 public void onNothingSelected(AdapterView<?> parent) {
 // Another interface callback
 }
 CatchGame cg;
 public TextView textView;
 public LinearLayout mainLayout;
 String[] spinnerValue = {"Difficulty", "Rookie", "Advanced", "Expert", "Master"};
 // start app
 @Override
 public void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 mainLayout = new LinearLayout(this);
 mainLayout.setOrientation(LinearLayout.VERTICAL);
 LinearLayout menuLayout = new LinearLayout(this);
 menuLayout.setBackgroundColor(Color.parseColor("#FFFFFF"));
 textView = new TextView(this);
 textView.setVisibility(View.VISIBLE);
 String str = "Score: 0";
 textView.setText(str);
 menuLayout.addView(textView);
 Button button = new Button(this);
 button.setText("Pause");
 button.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View v) {
 togglePausePlay();
 }
 });
 menuLayout.addView(button);
 Spinner spinner2 = new Spinner(this);
 spinner2.setOnItemSelectedListener(this);
 ArrayAdapter<String> adapter = new ArrayAdapter<>(MainActivity.this, android.R.layout.simple_list_item_1, spinnerValue);
 spinner2.setAdapter(adapter);
 menuLayout.addView(spinner2);
 mainLayout.addView(menuLayout);
 cg = new CatchGame(this, 5, "Jamie", onScoreListener);
 cg.setBackground(getResources().getDrawable(R.drawable.bg_land_mdpi));
 mainLayout.addView(cg);
 getWindow().requestFeature(Window.FEATURE_ACTION_BAR);
 getSupportActionBar().hide();
 setContentView(mainLayout);
 }
 private void togglePausePlay() {
 if (cg.paused) {
 // play
 // getSupportActionBar().hide();
 Toast.makeText(MainActivity.this, "Play", Toast.LENGTH_SHORT).show();
 } else {
 // pause
 // getSupportActionBar().show();
 Toast.makeText(MainActivity.this, "Pause", Toast.LENGTH_SHORT).show();
 }
 cg.paused = !cg.paused;
 }
 private OnScoreListener onScoreListener = new OnScoreListener() {
 @Override
 public void onScore(int score) {
 textView.setText("Score: " + score);
 }
 };
 interface OnScoreListener {
 void onScore(int score);
 }
 class CatchGame extends View {
 int NBRSTEPS; // number of discrete positions in the x-dimension; must be uneven
 String heroName;
 int screenW;
 int screenH;
 int[] x; // x-coordinates for falling objects
 int[] y; // y-coordinates for falling objects
 int[] hero_positions; // x-coordinates for hero
 Random random = new Random();
 int ballW; // width of each falling object
 int ballH; // height of ditto
 float dY; //vertical speed
 Bitmap falling, hero, jamie2, jamieleft, jamieright, falling2;
 int heroXCoord;
 int heroYCoord;
 int xsteps;
 int score;
 int offset;
 boolean gameOver; // default value is false
 boolean toastDisplayed;
 boolean paused = false;
 OnScoreListener onScoreListener;
 // constructor, load images and get sizes
 public CatchGame(Context context, int difficulty, String name, OnScoreListener onScoreListener) {
 super(context);
 NBRSTEPS = difficulty;
 heroName = name;
 this.onScoreListener = onScoreListener;
 x = new int[NBRSTEPS];
 y = new int[NBRSTEPS];
 hero_positions = new int[NBRSTEPS];
 int resourceIdFalling = 0;
 int resourceIdFalling2 = 0;
 int resourceIdHero = 0;
 if (heroName.equals("Jamie")) {
 resourceIdFalling = R.mipmap.falling_object2;
 resourceIdFalling2 = R.drawable.coconut_hdpi;
 resourceIdHero = R.drawable.left_side_hdpi;
 setBackground(getResources().getDrawable(R.mipmap.background));
 }
 falling = BitmapFactory.decodeResource(getResources(), resourceIdFalling); //load a falling image
 falling2 = BitmapFactory.decodeResource(getResources(), resourceIdFalling2); //load a falling image
 hero = BitmapFactory.decodeResource(getResources(), resourceIdHero); //load a hero image
 jamieleft = BitmapFactory.decodeResource(getResources(), R.drawable.left_side_hdpi); //load a hero image
 jamieright = BitmapFactory.decodeResource(getResources(), R.drawable.right_side_hdpi); //load a hero image
 ballW = falling.getWidth();
 ballH = falling.getHeight();
 }
 // set coordinates, etc.
 void initialize() {
 if (!gameOver) { // run only once, when the game is first started
 int maxOffset = (NBRSTEPS - 1) / 2;
 for (int i = 0; i < x.length; i++) {
 int origin = (screenW / 2) + xsteps * (i - maxOffset);
 x[i] = origin - (ballW / 2);
 hero_positions[i] = origin - hero.getWidth();
 }
 int heroWidth = hero.getWidth();
 int heroHeight = hero.getHeight();
 hero = Bitmap.createScaledBitmap(hero, heroWidth * 2, heroHeight * 2, true);
 hero = Bitmap.createScaledBitmap(hero, heroWidth * 2, heroHeight * 2, true);
 jamieleft = Bitmap.createScaledBitmap(jamieleft, jamieleft.getWidth() * 2, jamieright.getWidth() * 2, true);
 jamieright = Bitmap.createScaledBitmap(jamieright, jamieright.getWidth() * 2, jamieright.getWidth() * 2, true);
 heroYCoord = screenH - 2 * heroHeight; // bottom of screen
 }
 for (int i = 0; i < y.length; i++) {
 y[i] = -random.nextInt(1000); // place items randomly in vertical direction
 }
 offset = (NBRSTEPS - 1) / 2; // place hero at centre of the screen
 heroXCoord = hero_positions[offset];
 // initialize or reset global attributes
 dY = 2.0f;
 score = 0;
 gameOver = false;
 toastDisplayed = false;
 }
 // method called when the screen opens
 @Override
 public void onSizeChanged(int w, int h, int oldw, int oldh) {
 super.onSizeChanged(w, h, oldw, oldh);
 screenW = w;
 screenH = h;
 xsteps = w / NBRSTEPS;
 initialize();
 }
 // method called when the "game over" toast has finished displaying
 void restart(Canvas canvas) {
 toastDisplayed = true;
 initialize();
 draw(canvas);
 }
 // update the canvas in order to display the game action
 @Override
 public void onDraw(Canvas canvas) {
 if (toastDisplayed) {
 restart(canvas);
 return;
 }
 super.onDraw(canvas);
 int heroHeight = hero.getHeight();
 int heroWidth = hero.getWidth();
 int heroCentre = heroXCoord + heroWidth / 2;
 Context context = this.getContext();
 // compute locations of falling objects
 for (int i = 0; i < y.length; i++) {
 if (!paused) {
 y[i] += (int) dY;
 }
 // if falling object hits bottom of screen
 if (y[i] > (screenH - ballH) && !gameOver) {
 dY = 0;
 gameOver = true;
 paused = true;
 int duration = Toast.LENGTH_SHORT;
 final Toast toast = Toast.makeText(context, "GAME OVER!\nScore: " + score, duration);
 toast.show();
 Handler handler = new Handler();
 handler.postDelayed(new Runnable() {
 @Override
 public void run() {
 toast.cancel();
 toastDisplayed = true;
 }
 }, 3000);
 //Vibrator v = (Vibrator) context.getSystemService(context.VIBRATOR_SERVICE);
 // Vibrate for 3000 milliseconds
 //v.vibrate(3000);
 }
 // if the hero catches a falling object
 if (x[i] < heroCentre && x[i] + ballW > heroCentre &&
 y[i] > screenH - ballH - heroHeight) {
 y[i] = -random.nextInt(1000); // reset to new vertical position
 score += 1;
 onScoreListener.onScore(score);
 }
 }
 canvas.save(); //Save the position of the canvas.
 for (int i = 0; i < y.length; i++) {
 if (i % 2 == 0)
 canvas.drawBitmap(falling2, x[i], y[i], null); //Draw the falling on the canvas.
 else
 canvas.drawBitmap(falling, x[i], y[i], null); //Draw the falling on the canvas.
 }
 canvas.drawBitmap(hero, heroXCoord, heroYCoord, null); //Draw the hero on the canvas.
 canvas.restore();
 //Call the next frame.
 invalidate();
 }
 // event listener for when the user touches the screen
 @Override
 public boolean onTouchEvent(MotionEvent event) {
 if (paused) {
 paused = false;
 }
 int action = MotionEventCompat.getActionMasked(event);
 if (action != MotionEvent.ACTION_DOWN || gameOver) { // non-touchdown event or gameover
 return true; // do nothing
 }
 int coordX = (int) event.getX();
 int xCentre = (screenW / 2) - (hero.getWidth() / 2);
 int maxOffset = hero_positions.length - 1; // can't move outside right edge of screen
 int minOffset = 0; // ditto left edge of screen
 if (coordX < xCentre && offset > minOffset) { // touch event left of the centre of screen
 offset--; // move hero to the left
 if (coordX < heroXCoord)// + heroWidth / 2)
 hero = Bitmap.createScaledBitmap(jamieleft, jamieleft.getWidth(), jamieleft.getHeight(), true);
 }
 if (coordX > xCentre && offset < maxOffset) { // touch event right of the centre of screen
 offset++; // move hero to the right
 if (coordX > heroXCoord)
 hero = Bitmap.createScaledBitmap(jamieright, jamieright.getWidth(), jamieright.getHeight(), true);
 }
 heroXCoord = hero_positions[offset];
 return true;
 }
 }
}

Layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:paddingLeft="16dp"
 android:paddingRight="16dp"
 android:orientation="vertical" >
 <Button
 android:id="@+id/pause"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:layout_alignParentBottom="true"
 android:layout_column="0"
 android:text="@string/pause" />
 <TextView
 android:id="@+id/textView1"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_alignParentLeft="true"
 android:layout_alignParentTop="true"
 android:background="#FFFFFF"
 android:gravity="top"
 android:maxLines="2"
 android:scrollbars="vertical"
 android:textAppearance="?android:attr/textAppearanceLarge"
 android:textColor="#000000" />
 <Spinner android:id="@+id/Spinner01"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content" />
 <dev.android.jamie.CatchGame
 android:id="@+id/view"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:layout_weight="1"
 android:adjustViewBounds="true"
 android:background="#FFFFFF"
 android:paddingLeft="10dp"
 android:paddingRight="10dp"
 android:paddingTop="10dp" />
</LinearLayout>

Answer 1

 String str = parent.getItemAtPosition(pos).toString();

What does str mean? You proceed to use it to determine the level (i.e. str.equals("Rookie")) but it is not clear from the name (or even the method you use) that that is what str does.

Java 8 now supports switch-case statements for strings. You may eventually want to refactor this into some sort of "difficulty" enum, but for now, I would change the level select to a switch case instead of if-else chain. See this answer for the syntax.

 //setContentView(cg);
 mainLayout.addView(cg);
 getSupportActionBar().hide();
 setContentView(mainLayout);

Is repeated twice in level select, this should be refactored out into a method.

 boolean gameOver; // default value is false

Not something you should rely on. Explicitly assign it to false.

 int[] x; // x-coordinates for falling objects
 int[] y; // y-coordinates for falling objects

Why not something like xFalling and yFalling? x and y are used so often I would certainly forget (even with the comment) that this referred to falling objects in particular.

 hero = Bitmap.createScaledBitmap(hero, heroWidth * 2, heroHeight * 2, true);
 hero = Bitmap.createScaledBitmap(hero, heroWidth * 2, heroHeight * 2, true);

You call this twice in a row. I am not sure why you do this. Is this a mistake? If not there should be a comment why this is not a mistake.

In onCreate you have the following two lines:

 String str = "Score: 0";
 textView.setText(str);

You never use str (and the name is not descriptive). I would just set the textView directly like:

 textView.setText("Score: 0");