I have reviewed a lot of similar questions regarding not being able to launch an activity but they don'
t seem to quite match my problem. I am working on a simple black jack game but its force quitting. I suspect there is a problem with loading up the card png images I have. Stepping through the debugger it crashes right while in the resetGame() function. I'm sure I am doing something dumb.
My Logcat:
10-15 20:21:43.309: E/AndroidRuntime(2863): FATAL EXCEPTION: main
10-15 20:21:43.309: E/AndroidRuntime(2863): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.
smith.blackjack/com.
smith.blackjack.Main}: java.lang.NullPointerException
10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.access$600(ActivityThread.java:130)
10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
10-15 20:21:43.309: E/AndroidRuntime(2863): at android.os.Handler.dispatchMessage(Handler.java:99)
10-15 20:21:43.309: E/AndroidRuntime(2863): at android.os.Looper.loop(Looper.java:137)
10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.main(ActivityThread.java:4745)
10-15 20:21:43.309: E/AndroidRuntime(2863): at java.lang.reflect.Method.invokeNative(Native Method)
10-15 20:21:43.309: E/AndroidRuntime(2863): at java.lang.reflect.Method.invoke(Method.java:511)
10-15 20:21:43.309: E/AndroidRuntime(2863): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
10-15 20:21:43.309: E/AndroidRuntime(2863): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-15 20:21:43.309: E/AndroidRuntime(2863): at dalvik.system.NativeStart.main(Native Method)
10-15 20:21:43.309: E/AndroidRuntime(2863): Caused by: java.lang.NullPointerException
10-15 20:21:43.309: E/AndroidRuntime(2863): at com.
smith.blackjack.DeckOfCards.<init>(DeckOfCards.java:17)
10-15 20:21:43.309: E/AndroidRuntime(2863): at com.
smith.blackjack.Main.resetGame(Main.java:98)
10-15 20:21:43.309: E/AndroidRuntime(2863): at com.
smith.blackjack.Main.onCreate(Main.java:67)
10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.Activity.performCreate(Activity.java:5008)
10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
10-15 20:21:43.309: E/AndroidRuntime(2863): ... 11 more
My androidmanifest:
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.
smith.blackjack"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="11"
android:targetSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".Main"
android:label="@string/title_activity_main" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
Here is my Main.java
package com.
smith.blackjack;
import android.os.Bundle;
import android.app.Activity;
import android.content.res.AssetManager;
import android.graphics.drawable.Drawable;
import java.io.IOException;
import java.io.InputStream;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
public class Main extends Activity {
private ImageView dealerCard0;
private ImageView dealerCard1;
private ImageView dealerCard2;
private ImageView dealerCard3;
private ImageView playerCard0;
private ImageView playerCard1;
private ImageView playerCard2;
private ImageView playerCard3;
private ImageView imgResult;
private Button btnDeal;
private Button btnDraw;
private Button btnHold;
private DeckOfCards deckOfCards;
private int[] dealerValues;
private int dealerSum;
private int dealerCardNumber;
private int[] playerValues;
private int playerSum;
private int playerCardNumber;
private InputStream dealerHiddenCard;
private Card dealerCard;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
dealerCard0 = (ImageView) findViewById(R.id.dealerCard0);
dealerCard1 = (ImageView) findViewById(R.id.dealerCard1);
dealerCard2 = (ImageView) findViewById(R.id.dealerCard2);
dealerCard3 = (ImageView) findViewById(R.id.dealerCard3);
playerCard0 = (ImageView) findViewById(R.id.playerCard0);
playerCard1 = (ImageView) findViewById(R.id.playerCard1);
playerCard2 = (ImageView) findViewById(R.id.playerCard2);
playerCard3 = (ImageView) findViewById(R.id.playerCard3);
imgResult = (ImageView) findViewById(R.id.imgResult);
btnDeal = (Button) findViewById(R.id.deal);
btnDraw = (Button) findViewById(R.id.draw);
btnHold = (Button) findViewById(R.id.hold);
btnDeal.setOnClickListener(btnDealListener);
btnDraw.setOnClickListener(btnDrawListener);
btnHold.setOnClickListener(btnHoldListener);
resetGame();
}
private void resetGame(){
AssetManager assets = getAssets();
dealerValues = new int[4];
playerValues = new int[4];
dealerSum = 0;
playerSum = 0;
dealerCardNumber = 0;
playerCardNumber = 0;
for (int i = 0; i < 4; i++) {
dealerValues[i] = 0;
playerValues[i] = 0;
}
try {
InputStream stream = assets.open("cardback.png");
// stream = assets.open("cardback.png");
Drawable cardImage = Drawable.createFromStream(stream, null);
dealerCard0.setImageDrawable(cardImage);
dealerCard1.setImageDrawable(cardImage);
dealerCard2.setImageDrawable(cardImage);
dealerCard3.setImageDrawable(cardImage);
playerCard0.setImageDrawable(cardImage);
playerCard1.setImageDrawable(cardImage);
playerCard2.setImageDrawable(cardImage);
playerCard3.setImageDrawable(cardImage);
imgResult.setImageDrawable(cardImage);
deckOfCards = new DeckOfCards();
deckOfCards.shuffle();
assets.close();
}
catch (IOException e){
Log.e("Reset Game", "Error Loading", e);
}
}
public OnClickListener btnDealListener = new OnClickListener()
{
// @Override
public void onClick(View v) {
try {
AssetManager assets = getAssets();
InputStream stream;
// first player card
Card newCard;
newCard = deckOfCards.dealCard();
playerValues[playerCardNumber] = newCard.faceValue;
playerCardNumber++;
stream = assets.open(newCard.File);
Drawable cardImage = Drawable.createFromStream(stream, newCard.File);
playerCard0.setImageDrawable(cardImage);
assets.close();
// second player card
newCard = deckOfCards.dealCard();
playerValues[playerCardNumber] = newCard.faceValue;
playerCardNumber++;
stream = assets.open(newCard.File);
cardImage = Drawable.createFromStream(stream, newCard.File);
playerCard1.setImageDrawable(cardImage);
assets.close();
// first dealer card hidden
newCard = deckOfCards.dealCard();
dealerCard = newCard;
dealerValues[dealerCardNumber] = newCard.faceValue;
dealerCardNumber++;
dealerHiddenCard = assets.open(newCard.File);
stream = assets.open("cardback.png");
cardImage = Drawable.createFromStream(stream, "cardback");
dealerCard0.setImageDrawable(cardImage);
assets.close();
// second dealer card open
newCard = deckOfCards.dealCard();
dealerValues[dealerCardNumber] = newCard.faceValue;
dealerCardNumber++;
stream = assets.open(newCard.File);
cardImage = Drawable.createFromStream(stream, newCard.File);
dealerCard1.setImageDrawable(cardImage);
assets.close();
}
catch (IOException e){
Log.e("Deal", "Error Loading", e);
}
};
};
public OnClickListener btnDrawListener = new OnClickListener()
{
// @Override
public void onClick(View v) {
try {
AssetManager assets = getAssets();
InputStream stream;
// get next player card
Card newCard;
newCard = deckOfCards.dealCard();
playerValues[playerCardNumber] = newCard.faceValue;
playerCardNumber++;
stream = assets.open(newCard.File);
Drawable cardImage = Drawable.createFromStream(stream, newCard.File);
switch (playerCardNumber){
case 3:
playerCard2.setImageDrawable(cardImage);
case 4:
playerCard3.setImageDrawable(cardImage);
}
assets.close();
}
catch (IOException e){
Log.e("Draw", "Error Loading", e);
}
};
};
public OnClickListener btnHoldListener = new OnClickListener()
{
// @Override
public void onClick(View v) {
Drawable cardImage;
// evaluate player hand
playerSum = evaluate(playerValues);
if (playerSum > 21){
// player losses
}
// flip over the dealer hidden card
cardImage = Drawable.createFromStream(dealerHiddenCard, dealerCard.File);
Card newCard;
InputStream stream;
AssetManager assets = getAssets();
for (int i=2; i<4; i++){
dealerSum = evaluate(dealerValues);
if (dealerSum < 16 ) {
newCard = deckOfCards.dealCard();
dealerValues[dealerCardNumber] = newCard.faceValue;
dealerCardNumber++;
try {
stream = assets.open(newCard.File);
cardImage = Drawable.createFromStream(stream, newCard.File);
switch (dealerCardNumber){
case 3:
dealerCard2.setImageDrawable(cardImage);
case 4:
dealerCard3.setImageDrawable(cardImage);
}
assets.close();
}
catch (IOException e){
Log.e("Draw", "Error Loading", e);
}
if (dealerSum < playerSum) {
// player wins
}
if (dealerSum > playerSum){
// dealer wins
}
if (dealerSum == playerSum){
// it is a draw
}
}
}
};
};
public int evaluate (int[]values) {
int sumCards = 0;
for (int i = 0; i < 4; i++){
sumCards += values[i];
}
if (sumCards > 21) {
for (int i = 0; i < 4; i++){
if (values[i] == 11) {
values[i] = 1;
sumCards -= 10;
continue;
}
}
}
return sumCards;
}
}
My DeckOfCards class:
package com.
smith.blackjack;
import java.util.Random;
public class DeckOfCards {
private Card [] deck;
private int currentCard;
private static final int NUMBER_OF_CARDS = 52;
private static final Random randomNumbers = new Random();
public DeckOfCards () {
deck = new Card[NUMBER_OF_CARDS];
currentCard = 0 ;
for(int count = 0; count < deck.length; count++)
{
deck[count].faceValue = count + 1;
}
}
public void shuffle () {
currentCard = 0;
for (int first = 0; first < deck.length; first ++){
int second = randomNumbers.nextInt(NUMBER_OF_CARDS);
int temp = deck[first].faceValue;
deck[first].faceValue=deck[second].faceValue;
deck[second].faceValue = temp;
}
}
public Card dealCard(){
Card temp = new Card();
temp.faceValue = 0;
temp.File = "";
if(currentCard < deck.length)
{
temp.faceValue = deck[currentCard].faceValue / 4;
int suit = deck[currentCard].faceValue % 4;
String suitString = "";
switch (suit){
case 0:
suitString = "c";
case 1:
suitString = "d";
case 2:
suitString = "h";
case 3:
suitString = "s";
}
Integer face = temp.faceValue / 4 ;
String faceString = face.toString();
temp.File = faceString + suitString + ".png";
switch (temp.faceValue){
case 11:
temp.faceValue = 10;
case 12:
temp.faceValue = 10;
case 13:
temp.faceValue = 10;
}
return temp;
}
else
return temp;
}
}
