Java、ios、android開發總結(二) Android中全域變數和靜態變數的使用

1.盡量不要使用靜態變數,靜態常量除外(static final).

http://blog.csdn.net/zhangyue0503/article/details/7614944

2.自訂一個MyApplication繼承android.app.Application,在其中定義全域變數。
啟動Application時，系統會建立一個PID，即進程ID，所有的Activity就會在此進程上運行。那麼我們在Application建立的 時候初始化全域變數，同一個應用的所有Activity都可以取到這些全域變數的值

import android.app.Application;import android.util.Log;public class MyApplication extends Application {public static final String TAG = MyApplication.class.getSimpleName();private User user;@Overridepublic void onCreate() {Log.i(TAG, "onCreate ::");super.onCreate();}public User getUser() {return user;}public void setUser(User user) {this.user = user;}}

AndroidManifest.xml中

Activity、Service中

MyApplication app = (MyApplication)getApplication().MyApplication app = (MyApplication)getApplicationContext();app.getUser();app.setUser(xxx);

BroadcastReceiver中onReceive()方法

MyApplication app = (MyApplication)context.getApplicationContext();app.getUser();app.setUser(xxx);

ContentProvider中

MyApplication app = (MyApplication)getContext().getApplicationContext();app.getUser();app.setUser(xxx);

其他類中，可以通過傳遞context,通過如下方式調用

MyApplication app = (MyApplication)context.getApplicationContext();app.getUser();app.setUser(xxx);