android中application 关于全局变量
16lz
2021-01-23
转自:http://blog.csdn.net/leilu2008/article/details/6199961
android中application 关于全局变量
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。那究竟application有什么用处呢?来看看SDK中是如何描述的:
Base class for those who need to maintain global application state. You can provide your own implementation by specifying its name in your AndroidManifest.xml's < application> tag, which will cause that class to be instantiated for you when the process for your application/package is created.
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。
因小工程中涉及到的文件比较多,这里就贴代码撒。
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();
}
}
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
1. TestApplication application = (TestApplication) this.getApplication();
2. Log.i("data", ""+application.getCurIndex());
3. application.setCurIndex(5);
TestApplication application = (TestApplication) this.getApplication();
Log.i("data", ""+application.getCurIndex());
application.setCurIndex(5);
第二个Activity:
Java代码
1. TestApplication application = (TestApplication)this.getApplication();
2. Log.i("data", ""+application.getCurIndex());
3. application.setCurIndex(6);
TestApplication application = (TestApplication)this.getApplication();
Log.i("data", ""+application.getCurIndex());
application.setCurIndex(6);
第三个Activity:
Java代码
1. final TestApplication application = (TestApplication) this.getApplication();
2. Log.i("data", ""+application.getCurIndex());
final TestApplication application = (TestApplication) this.getApplication();
Log.i("data", ""+application.getCurIndex());
PS: <application android:icon="@drawable/icon" android:label="@string/app_name" android:name=".TestApplication">
android中application 关于全局变量
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。那究竟application有什么用处呢?来看看SDK中是如何描述的:
Base class for those who need to maintain global application state. You can provide your own implementation by specifying its name in your AndroidManifest.xml's < application> tag, which will cause that class to be instantiated for you when the process for your application/package is created.
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。
因小工程中涉及到的文件比较多,这里就贴代码撒。
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();
}
}
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
1. TestApplication application = (TestApplication) this.getApplication();
2. Log.i("data", ""+application.getCurIndex());
3. application.setCurIndex(5);
TestApplication application = (TestApplication) this.getApplication();
Log.i("data", ""+application.getCurIndex());
application.setCurIndex(5);
第二个Activity:
Java代码
1. TestApplication application = (TestApplication)this.getApplication();
2. Log.i("data", ""+application.getCurIndex());
3. application.setCurIndex(6);
TestApplication application = (TestApplication)this.getApplication();
Log.i("data", ""+application.getCurIndex());
application.setCurIndex(6);
第三个Activity:
Java代码
1. final TestApplication application = (TestApplication) this.getApplication();
2. Log.i("data", ""+application.getCurIndex());
final TestApplication application = (TestApplication) this.getApplication();
Log.i("data", ""+application.getCurIndex());
PS: <application android:icon="@drawable/icon" android:label="@string/app_name" android:name=".TestApplication">
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