例子一则
在main的onStart中注册一个BroadCastReceiver用来监听ACTION_CHANGING事件，在事件发生之后，修改textview的text。在onStop之中卸载改该listener，这样当第二个activity是透明的风格的时候main可以通过listener改变样式。
package org.cxz.lifeCycle;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;public class TransparentActivity extends Activity {private static final int MENU_OPTION_CHANGE = 1; @Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.transparent_activity);}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// TODO Auto-generated method stubsuper.onCreateOptionsMenu(menu);menu.add(0, MENU_OPTION_CHANGE, 0, R.string.change_bg);return true;}@Overridepublic boolean onMenuItemSelected(int featureId, MenuItem item) {super.onMenuItemSelected(featureId, item);switch (item.getItemId()) {case MENU_OPTION_CHANGE:changeMainBackGround();}return true;}private void changeMainBackGround() {Intent i = new Intent(MainActivity.ACTION_CHANGING);// startActivity(i);// not start an activitysendBroadcast(i);}}