方法在 Activity 中有效,但在片段中无效

Method worked in Activity but not in a fragment

我将我的 activity 转换为一个片段,方法 network_reinit_activity 之前工作正常,但是当我 运行 它在片段中时它不会,这是方法:

private final Context c = getActivity();

private void network_reinit_activity() {

    new Thread(new Runnable() {
        @Override
        public void run() {
            Activity mainAct = (Activity)c;
            Intent new_i = new Intent(getActivity(), NavigationActivity.class);
        mainAct.finish();
        Intent srv_i = new Intent(c, RadioStreamService.class);
        srv_i.putExtra("RS_STREAM_URL", RS_STREAM_URL);
        getActivity().stopService(srv_i);
        if(isInForeground)
    //          startActivity(new_i);
        }
    }).run();


}

片段没有完成,activity完成,请看下面代码

new Thread(new Runnable() {
        @Override
        public void run() {
            Activity mainAct = (Activity)c;
            Intent new_i = new Intent(getActivity(), NavigationActivity.class);
             getActivity().onBackPressed()   // to finish fragment
             Intent srv_i = new Intent(c, RadioStreamService.class);
             srv_i.putExtra("RS_STREAM_URL", RS_STREAM_URL);
             getActivity().stopService(srv_i);
             if(isInForeground)
             //          startActivity(new_i);
             }
    }).run();