Android 在Activity中关闭Activity

情景一：在Activity A关闭指定Activity B，（不确定ActivityB是否开启）

    1.在ActivityB中，设置静态变量

public static TheFirstPage_win8style instance;public static TheFirstPage_win8style getInstance(){return instance;}        @Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);instance=this;}       @Overrideprotected void onDestroy() {super.onDestroy();instance=null;}

    2.在ActivityA中，添加

       //如果IM界面的Activity，开启了。就关闭掉       if(ActivityB.instance!=null){ ActivityB.instance.finish();}