MainActivity： @Override public?void?onClick(View?view)?{ ????switch?(view.getId())?{ ????????case?R.id.bt_user: ????????????cf.setinitif(new?Interface_ChangeFragment()?{ ????????????????@Override ????????????????public?Fragment?initif()?{ ????????????????????return?tab_user; ????????????????} ? ????????????????@Override ????????????????public?int?initTAG()?{ ????????????????????return?3; ????????????????} ????????????}); ????????????break; ????????case?R.id.bt_find: ????????????cf.setinitif(new?Interface_ChangeFragment()?{ ????????????????@Override ????????????????public?Fragment?initif()?{ ????????????????????return?tab_found; ????????????????} ? ????????????????@Override ????????????????public?int?initTAG()?{ ????????????????????return?2; ????????????????} ????????????}); ????????????break; ????????case?R.id.bt_watchmoive: ????????????cf.setinitif(new?Interface_ChangeFragment()?{ ????????????????@Override ????????????????public?Fragment?initif()?{ ????????????????????return?tab_watchMoive; ????????????????} ? ????????????????@Override ????????????????public?int?initTAG()?{ ????????????????????return?1; ????????????????} ????????????}); ????????????break; ????????case?R.id.bt_selectsong: ????????????cf.setinitif(new?Interface_ChangeFragment()?{ ????????????????@Override ????????????????public?Fragment?initif()?{ ????????????????????return?tab_selectSong; ????????????????} ? ????????????????@Override ????????????????public?int?initTAG()?{ ????????????????????return?0; ????????????????} ????????????}); ????????????break; ????????case?R.id.bt_frist: ????????????break; ????} ????? ????? ????? ????? ????接口的實現類： ????public?class?ChangeFragment?extends?FragmentActivity?{ ????int?TAG; ????Tab_selectSong?tab_selectSong; ????Tab_watchMoive?tab_watchmoive; ????Tab_Found?tab_found; ????Tab_User?tab_user; ????public?void?setinitif(Interface_ChangeFragment?interface_changeFragment)?{ ????????FragmentManager?manager?=?getSupportFragmentManager(); ????????FragmentTransaction?fts?=?manager.beginTransaction(); ????????if?(interface_changeFragment.initif()?==?null)?{ ????????????TAG?=?interface_changeFragment.initTAG(); ????????????switch?(TAG)?{ ????????????????case?0: ???????????????????tab_selectSong?=?new?Tab_selectSong(); ????????????????????fts.add(R.id.activity_fragment,tab_selectSong); ????????????????????hideall(); ????????????????????fts.show(tab_selectSong); ????????????????????fts.commit(); ????????????????????break; ????????????????case?1: ????????????????????tab_watchmoive?=?new?Tab_watchMoive(); ????????????????????fts.add(R.id.activity_fragment,tab_watchmoive); ????????????????????hideall(); ????????????????????fts.show(tab_watchmoive); ????????????????????fts.commit(); ????????????????????break; ????????????????case?2: ????????????????????tab_found?=?new?Tab_Found(); ????????????????????fts.add(R.id.activity_fragment,tab_found); ????????????????????hideall(); ????????????????????fts.show(tab_found); ????????????????????fts.commit(); ????????????????????break; ????????????????case?3: ???????????????????tab_user?=?new?Tab_User(); ????????????????????fts.add(R.id.activity_fragment,tab_user); ????????????????????hideall(); ????????????????????fts.show(tab_user); ????????????????????fts.commit(); ????????????????????break; ????????????} ????????}?else?{ ????????????TAG?=?interface_changeFragment.initTAG(); ????????????switch?(TAG)?{ ????????????????case?0: ????????????????????hideall(); ????????????????????fts.show(tab_selectSong); ????????????????????fts.commit(); ????????????????????break; ????????????????case?1: ????????????????????hideall(); ????????????????????fts.show(tab_watchmoive); ????????????????????fts.commit(); ????????????????????break; ????????????????case?2: ????????????????????hideall(); ????????????????????fts.show(tab_found); ????????????????????fts.commit(); ????????????????????break; ????????????????case?3: ???????????????????hideall(); ????????????????????fts.show(tab_user); ????????????????????fts.commit(); ????????????????????break; ????????????} ? ????????} ????} ? ????private?void?hideall()?{ ????????FragmentManager?manager?=?getSupportFragmentManager(); ????????FragmentTransaction?fts?=?manager.beginTransaction(); ????????if(tab_selectSong!=null) ????????{ ????????????fts.hide(tab_selectSong); ????????} ????????if(tab_watchmoive!=null) ????????{ ????????????fts.hide(tab_watchmoive); ????????} ????????if(tab_found!=null) ????????{ ????????????fts.hide(tab_found); ????????} ????????if(tab_user!=null) ????????{ ????????????fts.hide(tab_user); ????????} ????} } ? 用的是按鈕的點擊事件new出一個匿名內部類，之所以這么做，是不想讓主MainAcitity變得臃腫，可是 結果出錯了，Log打印出來是java.lang.IllegalStateException:?Activity?has?been?destroyed ? 求大神解答為什么啊？難道不可以這么寫嗎？ 我也是一個新手，才開始寫我的第一個APP。求大神解答