Save settings and configurations.
5 different ways of data persistance:
onSavedInstanceState(): store state of views in k-v pairs (Bundles), used when screen rotates / app killed by system, temperary.SharedPreferences: save k-v pairs to a file, can save primitive types.Android kills background apps !!
→ onCreate() → Created →onStart() → Visible(can be seen on screen) → onResume() → Active(get focus, can interact with)
Active → onPause() → Paused(lose focus — same thing as Visible?) → onStop() → Stopped(disappeared) → onDestroy() → Destroyed(lifecycle ends)
when rotate screen, the function calling is:
onPause --> onStop --> onDestroy --> onCreate --> onStart --> onResume
note ...
https://developer.android.com/reference/android/util/Log.html
error/warning/info/debug/verboseMyClass.class.getSimpleName()
https://developer.android.com/guide/topics/resources/providing-resources.html
rather than creating list items as we scroll, keep them in a queue (recycling bin) → when scrolling, the list items are recycled and re-bind to new content. RecyclerView is better version of ListView.
Adaper: bind data from data source, and provide the RecyclerView with new views ...
So far: single screen with a single activity.
start activity from another activity: use Intents.
toy app: type some text, press button, and a new activity will appear with the typed words.
create activity in android studio: new → activity
call startActivity with an ...
Created 星期一 06 二月 2017
The minSDK is the lowest SDK level that your app can run on. You can choose what level of devices to support.
By comparison, the targetSDK is NOT a high pass filter -- it’s used only to declare ...
INF422的TD2, 这节TD是要做一个多线程筛选质数的程序, 关于java的多线程, 以前用过但是不知道啥意思, 在这里总结下.
为了实现多线程, 需要定义一个新的class, 有两种方法:
或者继承自Thread类, 或者实现Runnable接口(关键是重载run()方法).
写法1: 定义一个继承自Thread的内部类--
class [类名] extends Thread{
方法1;
方法2；
…
public void run(){
// …
}
属性1；
属性2；
…
}
或者用下面种内联(inline)的写法, 不用给这个类起名字了(不过还要给这个实例取名字):
private Thread [实例名] = new Thread () {
public void run() {
// ...
}
} ;
然后让进程开始, 就是:
t.start();
如果用 ...
这学期INF422, 第一节课就是android安装调试环境的搭建(居然要一节课?), 这里总结一下.
下载ADT-Bundle 解压缩以后啥都有了, 包含一个eclipse...
linux下的环境变量放在.bashrc文件, 加入下面一行:
PATH=$PATH:<dir>/sdk/tools/:<dir>/sdk/platform-tools/:
其中<dir>是放置SDK的目录地址.
测试一下好不好使, 在终端中输入android, 看是否会弹出SDK manager
可以用eclipse的AVDmanager做, 也可以用命令行做.
输入:
android list targets
找到想要的target(我们要4.1.2)的那个id(一个数字), 然后, 运行命令:
android create ...
new-->android application
开发位于最上层application
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