android:id and id are not same...

本文讨论了在定义XML布局文件中的元素ID时应注意的问题。作者提到,在定义ID时使用android:id而非id的重要性,因为错误地使用id可能导致在OnClickListener中通过findViewByI()找不到对应的视图(如按钮),返回null。

摘要生成于 C知道 ,由 DeepSeek-R1 满血版支持, 前往体验 >

You need to be careful when defining the xml elements of layout.

In the layout, mostly I specified the id by "android:id".

When I used "id" mistakenly, "findViewByI()" cannot find the view (e.g., a button) in the OnClickListener's "onClick()" definition (it returned null)!

### Android UID System Overview In the context of the Android operating system, `android.uid.system` plays a crucial role in defining how applications interact with core system services and resources. Applications that declare `android:sharedUserId="android.uid.system"` within their manifest are assigned this specific user ID (UID). This assignment allows these apps to share the same Linux user ID as other components signed by the platform key[^1]. Applications sharing this UID gain elevated privileges necessary for performing operations typically restricted to system-level processes or those closely integrated into the device's functionality. For instance, such an application can access APIs not available to regular third-party apps due to security restrictions. To achieve this level of integration: - The app must be signed using the platform certificate. - Configuration includes specifying both the shared user ID and ensuring proper signing configurations in build scripts like Gradle files[^3]. For example, configuring the signing configuration involves setting up details about where the keystore is located along with passwords required during compilation time: ```gradle signingConfigs { debug { storeFile file('path/to/keystore.jks') storePassword 'your_store_password' keyAlias 'alias_name' keyPassword 'your_key_password' } } ``` This setup ensures only authorized entities—those possessing correct credentials—can compile code intended to run under `android.uid.system`. Moreover, declaring `<manifest xmlns:android="http://schemas.android.com/apx/android" package="com.example.app" android:sharedUserId="android.uid.system">` inside the `AndroidManifest.xml` ties together all aspects needed for running at higher privilege levels on behalf of the system itself[^2]. --related questions-- 1. What are some examples of API calls limited exclusively to applications holding the `android.uid.system`? 2. How does one obtain or generate certificates suitable for assigning the `android.uid.system` to custom-built applications? 3. Can multiple independent developers securely collaborate while developing software meant to operate under `android.uid.system`, considering its stringent requirements around authentication?
评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值