activity has been destroyed ，使用 fragment时

今天 程序中，忽然遇到了这个bug，现象，viewpager里的fragment 嵌套fragment，有使用transation.commitAllowingStateLoss方法，当退出 这个activity，再进入，在fragment里面 切换 fragment时，出现 activity has been destroyed   这个bug，下面贴出 部分代码：

fm = getActivity().getSupportFragmentManager();
FragmentTransaction transaction = fm.beginTransaction();
transaction.add(R.id.frame_layout, wksFragment, "wks");
transaction.add(R.id.frame_layout, jxzFragment, "jxz");
transaction.add(R.id.frame_layout, ywcFragment, "ywc");
transaction.commit();

fm.beginTransaction().hide(wksFragment).hide(ywcFragment).show(jxzFragment).commitAllowingStateLoss();

//未开赛
weiRl.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
change(weiRl, weiTv);
//weiTv.setCompoundDrawables();
fm.beginTransaction().hide(jxzFragment).hide(ywcFragment).show(wksFragment).commitAllowingStateLoss();
}
});
//进行中
onRl.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
change(onRl, onTv);
fm.beginTransaction().hide(wksFragment).hide(ywcFragment).show(jxzFragment).commitAllowingStateLoss();
}
});
//已完场
wanRl.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
change(wanRl, wanTv);
fm.beginTransaction().hide(jxzFragment).hide(wksFragment).show(ywcFragment).commitAllowingStateLoss();

}
});

最后 解决办法，

发现，我在要调用commitAllowingStateLoss方法的fragment 上， 在onViewCreated方法里，加入了非空判断

如下

@Overridepublic void onViewCreated(View view, @Nullable Bundle savedInstanceState) {if (fm== null) {wksFragment = new QuWksFragment();jxzFragment = new QuJxzFragment();ywcFragment = new QuYwcFragment();fm = getActivity().getSupportFragmentManager();
FragmentTransaction transaction = fm.beginTransaction();
transaction.add(R.id.frame_layout, wksFragment, "wks");
transaction.add(R.id.frame_layout, jxzFragment, "jxz");
transaction.add(R.id.frame_layout, ywcFragment, "ywc");
transaction.commit();

fm.beginTransaction().hide(wksFragment).hide(ywcFragment).show(jxzFragment).commitAllowingStateLoss();initListerner();}}

然后 把 非空 判断去掉，问题就解决了。