当第一次创建一个活动时，系统会调用OnContentChanged()方法作为第一个方法，当一个活动被杀死时，系统的最后一次调用是OnDetachedFromWindow()方法，但是android文档表示在OnCreate之间发生活动的整个生命周期()和OnDestroy()。为什么？请帮我理解这些方法之间的区别。

码：

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，onCreate()方法调用onContentChanged()，onDetachedFromWindow()在onDestroy()之后被调用。为什么？