Question

java中Activity是什么？

Answer 1

是android里面的。

// --------------创建Activity----------------
public class ExampleActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {//此方法必须要有
super.onCreate(savedInstanceState);
// The activity is being created.
}
@Override
protected void onStart() {
super.onStart();
// The activity is about to become visible.
}
@Override
protected void onResume() {
super.onResume();
// The activity has become visible (it is now "resumed").
}
@Override
protected void onPause() {
super.onPause();
// Another activity is taking focus (this activity is about to be "paused").
}
@Override
protected void onStop() {
super.onStop();
// The activity is no longer visible (it is now "stopped")
}
@Override
protected void onDestroy() {
super.onDestroy();
// The activity is about to be destroyed.
}
}
// -------------在manifest中注册Activity------
//ExampleActivity在启动应用的时候被启动
<activity android:name=".ExampleActivity" android:icon="@drawable/app_icon">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
//---------------启动 Activity------------
Intent intent = new Intent(this, SignInActivity.class);//SignInActivity为要跳转的Activity
startActivity(intent);

Answer 2

应该指的是安卓应用层编程里面的一个非常重要的概念
给予界面赋予完整的生命周期，也就是不只是界面
实际上底层的进程完全抽象出一个Activity
语言不过工具而已

Answer 3

楼主，这个是android中的常用的界面类，在android sdk里面

Answer 4

在android 程序开发中使用到的一种组件

Answer 5

好像是android中的东西吧？