ArrayList作为全局变量 [英] ArrayList as global variable

问题描述

我创建了类似应用程序扩展的类

I created class that extend of application like that

package com.appnetics;

import java.util.ArrayList;

import android.app.Application;

public class GlobalVariables extends Application {

    public ArrayList<Encounter> encounters;

}

并将其设置为像这样的表现

and set it in manifist like this

<application
android:name="GlobalVariables"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >

在一个Actiity中我使用此代码填充此数组

in one Actiity I fill this array using this code

GlobalVariables appState = new GlobalVariables();
appState.encounters =new ArrayList<Encounter>(); 
................
then add 

当试图使用它时会崩溃并出现null异常，我在另一个活动或类中使用它

when trying to use it it crash with null exception, I use it in another activity or class like that

    GlobalVariables appState = new GlobalVariables();

    Encounter EncounterObject = appState.encounters.get(position);

请找不到的东西，如何修复

is there something missing please , how to fix that

推荐答案

这是 GlobalVariables 类的实例变量，所以每次创建新的实例 GlobalVariables ，您将获得一个单独的变量。

It's an instance variable of the GlobalVariables class, so every time you create a new instance of GlobalVariables, you'll get a separate variable.

如果您真的想要一个全局变量，它应该是一个静态变量 - 但即便如此，只有当你在同一个进程中的活动之间共享数据时才会这样。您应该阅读 Android应用程序框架常见问题解答以获取更多信息。

If you really want a global variable, it should be a static variable - but even that will only work if you're sharing data between activities in the same process. You should read the Android Application Framework FAQ for more information.

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