拥有创建应用程序的一个子类的麻烦共享多个活动数据 [英] Having trouble creating a subclass of application to share data with multiple Activities

问题描述

我刚刚完成了几个在我的游戏活动，现在我要开始来连接他们两个使用真正的游戏数据，而不是测试数据，我只用，以确保每一件工作。由于多个活动将需要访问本场比赛的数据，我开始研究最好的办法将这些数据传递给我的活动。

I just finished a couple of activities in my game and now I was going to start to wire them both up to use real game data, instead of the test data I was using just to make sure each piece worked. Since multiple Activities will need access to this game data, I started researching the best way to pass this data to my Activities.

我知道如何使用putExtra与意图，但我GAMEDATA类有相当多的数据，而不是只是简单的键值对。除了相当多的基本数据类型，它也有很大的阵列。我真的不希望尝试，并通过这一切，除非我可以通过整个对象，而不是仅仅键/数据对。

I know about using putExtra with intents, but my GameData class has quite a bit of data and not just simple key value pairs. Besides quite a few basic data types, it also has large arrays. I didn't really want to try and pass all that, unless I can pass the entire object, instead of just key/data pairs.

我读了下面的帖子，并认为这将是一段路要走，但到目前为止，我还没有得到它的工作。

I read the following post and thought it would be the way to go, but so far, I haven't got it to work.

如何在Android中声明全局变量？

我创建了一个简单的测试应用程序来试试这个方法了，但它总是崩溃，我的code似乎看起来一样在上面的帖子 - 除了我改了名字。这里是我得到的错误。有人可以帮助我理解我在做什么错了？

I created a simple test app to try this method out, but it keeps crashing and my code seems to look the same as in the post above - except I changed the names. Here is the error I am getting. Can someone help me understand what I am doing wrong?

12-23 00：50：49.762：ERROR / AndroidRuntime（608）：java.lang.ClassCastException：产生的原因android.app.Application

12-23 00:50:49.762: ERROR/AndroidRuntime(608): Caused by: java.lang.ClassCastException: android.app.Application

据崩溃以下语句：

GameData newGameData = ((GameData)getApplicationContext());  

下面是我的code：

package mrk.examples.MainActivity;

import android.app.Application;

public class GameData extends Application {
    private int intTest;

    GameData () {
        intTest = 0;
    }

    public int getIntTest(){
        return intTest;
    }

    public void setIntTest(int value){
        intTest = value;
    }
}

//我的主要活动

// My main activity

package mrk.examples.MainActivity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;

public class MainActivity extends Activity {

    int intLocal;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        GameData newGameData = ((GameData) getApplicationContext());
        newGameData.setIntTest(0);
        intLocal = newGameData.getIntTest();
        Log.d("MainActivity", "IntLocal = " + intLocal);
        newGameData.setIntTest(1);
        Log.d("MainActivity", "IntLocal = " + intLocal
                + " newGameData IntTest: " + newGameData.getIntTest());
        Intent intentNew = new Intent(this, PassData2Activity.class);
        startActivity(intentNew);
    }
}

//我的测试活动，看它是否能够从上次活动访问数据和previous状态

// My test Activity to see if it can access the data and its previous state from the last activity

package mrk.examples.MainActivity;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class PassData2Activity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        GameData gamedataPass = ((GameData)getApplicationContext());
        Log.d("PassData2Activity", "gamedatapass IntTest =  " +
                                         gamedataPass.getIntTest());           
    }
}

下面是我的清单的相关部分：

Below is the relevant portion of my manifest:

<application android:icon="@drawable/icon"
             android:label="@string/app_name">    
    <activity android:name=".MainActivity"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>            
    </activity>

    <activity android:name=".PassData2Activity"></activity>

</application> 

<application android:name=".GameData"
         android:icon="@drawable/icon"
         android:label="@string/app_name">        
</application>

请帮助我了解为什么这个code崩溃？

Please help me understand why this code is crashing?

另外，如果你认为这仅仅是错误的做法，让多种活动可以访问相同的数据，请给你的建议。请记住，我说的是相当多的变量和一些大型的阵列。

Also, if you think this is just the wrong approach to let multiple activities have access to the same data, please give your suggestion. Please keep in mind that I am talking about quite a few variables and some large arrays.

推荐答案

我不知道，但我觉得要在清单中这些标记合并成一个单一的标签，像这样。 （您可能还需要充分阐明，而不是使用初始出您的应用程序包的名称，。作为一种快捷方式。）

I'm not sure, but I think you want to combine those tags in the manifest into a single tag, like this. (You may also need to fully spell out the package name of your app, instead of using the initial . as a shortcut.)

<application android:icon="@drawable/icon"
             android:name=".GameData"
             android:label="@string/app_name">    
    <activity android:name=".StaticGameData"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>            
    </activity>

    <activity android:name=".PassData2Activity"></activity>
</application> 

（顺便说一句，我会避免使用名称 GAMEDATA 应用程序，而 StaticGameData 的活动;这些都让我觉得 StaticGameData 将是一个子类 GAMEDATA ）

(By the way, I'd avoid using the names GameData for the application, and StaticGameData for the activity; these make me think that StaticGameData would be a subclass of GameData.)

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