Activity 方法：onCreate() 和 onDestroy()

当第一次创建活动时，系统会调用OnContentChanged()方法作为系统的第一个方法和最后一个调用是OnDetachedFromWindow()方法当一个 Activity 被杀死时，但 android 文档说 Activity 的整个生命周期发生在OnCreate() and OnDestroy()。为什么？请帮助我理解这些方法之间的区别。

Code:

import android.app.Activity;
import android.content.res.Configuration;
import android.os.Bundle;
import android.widget.Toast;

public class ActivitylifecycleActivity extends Activity {
    /** Called when the activity is first created. */

    @Override
    public void onContentChanged() {
        super.onContentChanged();   
        Toast.makeText(getApplicationContext(),"1. onContentChanged()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Toast.makeText(getApplicationContext(),"2. onCreate()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onStart() {
        super.onStart();
        Toast.makeText(getApplicationContext(),"3. onStart()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onRestoreInstanceState(Bundle restoreInstanceState) {
        Toast.makeText(getApplicationContext(),"4. onRestoreinstaneState()", Toast.LENGTH_SHORT).show();
        super.onRestoreInstanceState(restoreInstanceState);
    }

    @Override
    public void onRestart() {
        super.onRestart();
        Toast.makeText(getApplicationContext(),"5. onRestart()", Toast.LENGTH_SHORT).show();
    }

    @Override
    protected void onPostCreate(Bundle onpostcrete) {
        super.onPostCreate(onpostcrete);
        Toast.makeText(getApplicationContext(),"6. onPostCreate()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onResume() {
        super.onResume();
        Toast.makeText(getApplicationContext(),"7. onResume()", Toast.LENGTH_SHORT).show();
    }

    @Override
    protected void onPostResume() {
        super.onPostResume();
        Toast.makeText(getApplicationContext(),"8. onPostResume()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onAttachedToWindow() {
        super.onAttachedToWindow();
        Toast.makeText(getApplicationContext(),"9. onAttachedToWindow()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onWindowFocusChanged(boolean bo) {
        super.onWindowFocusChanged(true);
        Toast.makeText(getApplicationContext(),"10. onWindowFocusChanged()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onUserLeaveHint() {
        super.onUserLeaveHint();
        Toast.makeText(getApplicationContext(),"11. onUserLeaveHint()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onUserInteraction() {
        super.onUserInteraction();
        ii=0;
        Toast.makeText(getApplicationContext(),"12. onUserInteraction()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onSaveInstanceState(Bundle savedInstanceState) {
        super.onSaveInstanceState(savedInstanceState);
        Toast.makeText(getApplicationContext(),"13. onSaveInstanceState()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onPause() {
        super.onPause();
        Toast.makeText(getApplicationContext(),"14. onPause()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onStop() {
        super.onStop();
        Toast.makeText(getApplicationContext(),"15. onStop()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Toast.makeText(getApplicationContext(),"16. onDestroy()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        Toast.makeText(getApplicationContext(),"17. onDetachedFromWindow()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        Toast.makeText(getApplicationContext(),"18. onConfigurationChanged()", Toast.LENGTH_SHORT).show();
    }

    @Override
    public boolean onSearchRequested() {
        super.onSearchRequested();
        Toast.makeText(getApplicationContext(),"19. onSearchRequested()", Toast.LENGTH_SHORT).show();
        return false;
    }
}

在这段代码中，onContentChanged()之前被调用onCreate()方法和onDetachedFromWindow()之后被调用onDestroy(). Why?

onCreate():

当一个活动开始它的生命时onCreate()叫做。它在活动的生命周期中仅被调用一次。

onDestroy():

onDestroy()当活动完成其生命周期时调用。它也在活动的生命周期中被调用一次。

onContentChanged():

每当屏幕的内容视图发生变化时（由于调用Window.setContentView or Window.addContentView）。例如，您向活动添加新视图或想要通过调用刷新列表notifyDataSetChanged().

onDetachedFromWindow():

当与该活动关联的主窗口已与窗口管理器分离时调用。例如，当当前 Activity 进入后台或另一个 Activity 出现在当前 Activity 前面时，就会调用它。