關鍵代碼：

public?class?FragmentActivity?extends?AppCompatActivity{

????private?static?final?String?TAG?=?"FragmentActivity";

????private?ImageButton?btn_weixin;
????private?ImageButton?btn_friend;
????private?ImageButton?btn_address;
????private?ImageButton?btn_settings;

????private?LinearLayout?lay_weixin;
????private?LinearLayout?lay_friend;
????private?LinearLayout?lay_address;
????private?LinearLayout?lay_settings;

????private?Fragment?weixinFragment;
????private?Fragment?friendFragment;
????private?Fragment?addressFragment;
????private?Fragment?settingsFragment;
????private?FragmentManager?fragmentManager;


????private?static?final?int?WEIXIN_POSITION?=?0;
????private?static?final?int?FRIEND_POSITION?=?1;
????private?static?final?int?ADDRESS_POSITION?=?2;
????private?static?final?int?SETTINGS_POSITION?=?3;


????@Override
????protected?void?onCreate(Bundle?savedInstanceState)?{
????????requestWindowFeature(Window.FEATURE_NO_TITLE);
????????super.onCreate(savedInstanceState);
????????setContentView(R.layout.activity_fragment1_tab);
????????initData();
????????initView();
????????setSelectFragment(WEIXIN_POSITION);//設置頁面默認選中的Fragment
????}

????//初始化Fragment
????private?void?initData()?{
????????weixinFragment?=?new?WeixinFragment();
????????friendFragment?=?new?FriendFragment();
????????addressFragment?=?new?AddressFragment();
????????settingsFragment?=?new?SettingsFragment();
????????fragmentManager?=?getSupportFragmentManager();
????}

????private?void?initView()?{
????????lay_weixin?=?(LinearLayout)?findViewById(R.id.lay_weixin);
????????lay_friend?=?(LinearLayout)?findViewById(R.id.lay_friend);
????????lay_address?=?(LinearLayout)?findViewById(R.id.lay_address);
????????lay_settings?=?(LinearLayout)?findViewById(R.id.lay_settings);

????????btn_weixin?=?(ImageButton)?findViewById(R.id.btn_weixin);
????????btn_friend?=?(ImageButton)?findViewById(R.id.btn_friend);
????????btn_address?=?(ImageButton)?findViewById(R.id.btn_address);
????????btn_settings?=?(ImageButton)?findViewById(R.id.btn_settings);

????}

????//設置我們的tab所選擇的對應的Fragment
????private?void?setSelectFragment(int?position){
????????FragmentTransaction?fragmentTransaction?=?fragmentManager.beginTransaction();
????????resetImg();
????????removeAllFragment(fragmentTransaction);
????????switch?(position){
????????????case?WEIXIN_POSITION:
????????????????fragmentTransaction.add(R.id.content,weixinFragment);
????????????????btn_weixin.setImageResource(R.mipmap.tab_weixin_pressed);
????????????????break;
????????????case?FRIEND_POSITION:
????????????????fragmentTransaction.add(R.id.content,friendFragment);
????????????????btn_friend.setImageResource(R.mipmap.tab_find_frd_pressed);
????????????????break;
????????????case?ADDRESS_POSITION:
????????????????fragmentTransaction.add(R.id.content,addressFragment);
????????????????btn_address.setImageResource(R.mipmap.tab_address_pressed);
????????????????break;
????????????case?SETTINGS_POSITION:
????????????????fragmentTransaction.add(R.id.content,settingsFragment);
????????????????btn_settings.setImageResource(R.mipmap.tab_settings_pressed);
????????????????break;
????????}
????????fragmentTransaction.commit();
????}

????/**
?????*?取消所有fragment的顯示
?????*/
????private?void?removeAllFragment(FragmentTransaction?fragmentTransaction){
????????fragmentTransaction.remove(weixinFragment);
????????fragmentTransaction.remove(friendFragment);
????????fragmentTransaction.remove(addressFragment);
????????fragmentTransaction.remove(settingsFragment);
????}

????public?void?doOnClick(View?view){
????????switch?(view.getId()){
????????????case?R.id.lay_weixin:
????????????????setSelectFragment(WEIXIN_POSITION);
????????????????break;
????????????case?R.id.lay_friend:
????????????????setSelectFragment(FRIEND_POSITION);
????????????????break;
????????????case?R.id.lay_address:
????????????????setSelectFragment(ADDRESS_POSITION);
????????????????break;
????????????case?R.id.lay_settings:
????????????????setSelectFragment(SETTINGS_POSITION);
????????????????break;
????????}
????}

????/**
?????*?將ImageButton的圖片全部置為normal
?????*/
????private?void?resetImg()?{
????????btn_weixin.setImageResource(R.mipmap.tab_weixin_normal);
????????btn_friend.setImageResource(R.mipmap.tab_find_frd_normal);
????????btn_address.setImageResource(R.mipmap.tab_address_normal);
????????btn_settings.setImageResource(R.mipmap.tab_settings_normal);
????}

}

請問我這樣寫問題在哪里？我的tab，如果重復的點擊自己，Fragment就加載不出來了