Android中application 全局变量
android编程中,application这样的名词似乎变得那样的不常见,而让大家更为熟悉的是activity、intent、provider、broadcast和service。但其实android中的application也有着它自身的用处。打开manifest文件,会看到有一个application配置标签,这就是有关application的使用了。
就是说application是用来保存全局变量的,并且是在package创建的时候就跟着存在了。所以当我们需要创建全局变量的时候,不需要再像j2se那样需要创建public权限的static变量,而直接在application中去实现。只需要调用Context的getApplicationContext或者Activity的getApplication方法来获得一个application对象,再做出相应的处理。
application文件:
Java代码:
public class TestApplication extends Application { private int curIndex; public int getCurIndex() { return curIndex; } public void setCurIndex(int curIndex) { this.curIndex = curIndex; } @Override public void onCreate() { super.onCreate(); } @Override public void onTerminate() { super.onTerminate(); } } public class TestApplication extends Application { private int curIndex; public int getCurIndex() { return curIndex; } public void setCurIndex(int curIndex) { this.curIndex = curIndex; } @Override public void onCreate() { super.onCreate(); } @Override public void onTerminate() { super.onTerminate(); } }
第二个Activity:
TestApplication application = (TestApplication)this.getApplication(); Log.i("data", ""+application.getCurIndex()); application.setCurIndex(6); TestApplication application = (TestApplication)this.getApplication(); Log.i("data", ""+application.getCurIndex()); application.setCurIndex(6);
application中有一个curIndex和setter getter方法。
第一个acitivty中对application进行的操作:
Java代码:
TestApplication application = (TestApplication) this.getApplication(); Log.i("data", ""+application.getCurIndex()); application.setCurIndex(5); TestApplication application = (TestApplication) this.getApplication(); Log.i("data", ""+application.getCurIndex()); application.setCurIndex(5);
第三个Activity:
final TestApplication application = (TestApplication) this.getApplication(); Log.i("data", ""+application.getCurIndex()); final TestApplication application = (TestApplication) this.getApplication(); Log.i("data", ""+application.getCurIndex());
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