简书链接:【原创】fragment隐藏显示方式来控制切换tab支持横竖屏记忆回收，切换过快又使用动画导致重叠问题解决
文章字数：516,阅读全文大约需要2分钟

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    static long lastClickTime = 0;

    public static Fragment switchPagesByHide(Map<Integer, PairX<String, SoftReference<Fragment>>> map, FragmentManager fragmentManager, int fragment_container_id, int key) {

        Fragment fragment;
        ArrayList<Fragment> needHideFragments = new ArrayList<>();
        for (Integer currentKey : map.keySet()) {
            if (currentKey == key) {
                continue;
            }
            PairX<String, SoftReference<Fragment>> pair = map.get(currentKey);
            fragment = pair.second.get();
            if (fragment == null) {
                fragment = fragmentManager.findFragmentByTag(getFragmentTagName(pair.first));
                if (fragment != null && fragment.isAdded()) {
                    needHideFragments.add(fragment);
                    if (BuildConfig.DEBUG && AppContext.DEBUG_) {
                        Log.w(TAG, "from tag fragment :" + fragment.getClass().getSimpleName());
                    }
                }
                continue;
            } else if (fragment.isAdded()) {
                needHideFragments.add(fragment);
            } else {
                fragment = fragmentManager.findFragmentByTag(getFragmentTagName(fragment.getClass()));
                if (fragment != null && fragment.isAdded()) {
                    needHideFragments.add(fragment);
                    if (BuildConfig.DEBUG && AppContext.DEBUG_) {
                        Log.w(TAG, " and instance not add,from tag fragment :" + fragment.getClass().getSimpleName());
                    }
                }
            }
        }
        PairX<String, SoftReference<Fragment>> pair = map.get(key);

        Fragment currentFragment = pair.second.get();
        Fragment tagCurrentFragment = fragmentManager.findFragmentByTag(getFragmentTagName(currentFragment.getClass().getName()));
        if (currentFragment == null) {
            if (tagCurrentFragment != null) {
                currentFragment = tagCurrentFragment;
            } else {
                try {
                    currentFragment = (Fragment) Class.forName(pair.first).newInstance();
                    pair.second = new SoftReference<>(currentFragment);
                } catch (Throwable e) {
                    e.printStackTrace();
                }
            }
        } else if (tagCurrentFragment != null && tagCurrentFragment.isAdded()) {//当前如果tag里面有还是需要隐藏它.
            needHideFragments.add(tagCurrentFragment);
        }

        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        for (Fragment fragment_ : needHideFragments) {
            //if (!fragment_.isHidden()) {
            if (BuildConfig.DEBUG && AppContext.DEBUG_) {
                if (fragment_.isHidden()) {
                    Log.w(TAG, "REPEAT_HIDE_" + fragment_.getClass().getSimpleName());
                } else {

                    Log.w(TAG, "HIDE_" + fragment_.getClass().getSimpleName());
                }
            }
            fragmentTransaction.hide(fragment_);
//            popBackStackImmediate
            //}
        }
        if (!(currentFragment instanceof MyFragment) && !AppUtils.isPadBySizeLarge(AppContext.getInstance())) {//因为隐藏了actionbar，所以会出现白屏，不能动画
            long currentMs = System.currentTimeMillis();
            if (lastClickTime == 0 || currentMs - lastClickTime > 5500) {
                currentFragment.setEnterTransition(createTransition());
                currentFragment.setReenterTransition(createTransition());
                lastClickTime = currentMs;
                if(BuildConfig.DEBUG){
                    Log.w(TAG,"_fragment anim:"+currentFragment.getClass().getSimpleName());
                }
            }else{//必须设置，否则依然会因为切换过快导致重复.
                currentFragment.setEnterTransition(null);
                currentFragment.setReenterTransition(null);
            }

        }
        if (currentFragment.isAdded()) {
            if (BuildConfig.DEBUG) {
                Log.w(TAG, "FRAGMENT_SHOW:"+currentFragment.getClass().getSimpleName()+",before_hidden:" + currentFragment.isHidden() + ",save:" + currentFragment.isStateSaved() + ",detach:" + currentFragment.isDetached() + ",add:" + currentFragment.isAdded());
            }
            fragmentTransaction.show(currentFragment);
        } else {
            if (BuildConfig.DEBUG) {
                Log.w(TAG, "FRAGMENT_ADD:" + currentFragment.isHidden() + ",save:" + currentFragment.isStateSaved() + ",detach:" + currentFragment.isDetached() + ",add:" + currentFragment.isAdded() + "," + currentFragment);
            }
            fragmentTransaction.add(fragment_container_id == 0 ? R.id.fragment_space : fragment_container_id, currentFragment, getFragmentTagName(currentFragment.getClass()));
        }
        fragmentTransaction.commitAllowingStateLoss();

        return currentFragment;
    }

解决办法，频繁点击就直接清除动画，不使用动画

如果还是有重叠，最后经过修改的版本是这样的

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    public static Fragment switchPagesByHide(Map<Integer, PairX<String, SoftReference<Fragment>>> map, FragmentManager fragmentManager, int fragment_container_id, int key, DialogUtils.INotify<Fragment> onHiddenNotify, DialogUtils.INotify<Fragment> onShowNotify) {
        Fragment fragment;
        ArrayList<Fragment> needHideFragments = new ArrayList<>();
        for (Integer loopKey : map.keySet()) {
            if (loopKey == key) {
                continue;
            }
            PairX<String, SoftReference<Fragment>> pair = map.get(loopKey);
            fragment = pair.second.get();
            if (fragment == null) {
                fragment = fragmentManager.findFragmentByTag(getFragmentTagName(pair.first));
                if (fragment != null) {
//                if (fragment != null && fragment.isAdded()) {
                    needHideFragments.add(fragment);
                    if (BuildConfig.DEBUG && AppContext.DEBUG_) {
                        Log.w(TAG, "from tag fragment :" + fragment.getClass().getSimpleName());
                    }
                }
                continue;
           /* } else if (!fragment.isHidden()) {
                needHideFragments.add(fragment);*/
            } else {
//                fragment = fragmentManager.findFragmentByTag(getFragmentTagName(fragment.getClass()));
//                if (fragment != null && !fragment.isHidden()) {
                needHideFragments.add(fragment);
                if (BuildConfig.DEBUG && AppContext.DEBUG_) {
                    Log.w(TAG, " and instance not add,from tag fragment :" + fragment.getClass().getSimpleName());
                }
//                }
            }
        }
        PairX<String, SoftReference<Fragment>> pair = map.get(key);
        Fragment currentFragment = pair.second.get();
        Fragment tagCurrentFragment = currentFragment == null ? null : fragmentManager.findFragmentByTag(getFragmentTagName(currentFragment.getClass().getName()));
        if (currentFragment == null) {
            if (tagCurrentFragment != null) {
                currentFragment = tagCurrentFragment;
            } else {
                try {
                    currentFragment = (Fragment) Class.forName(pair.first).newInstance();
                    pair.second = new SoftReference<>(currentFragment);
                } catch (Throwable e) {
                    e.printStackTrace();
                }
            }
        } else if (tagCurrentFragment != null && tagCurrentFragment.isAdded()) {//当前如果tag里面有还是需要隐藏它.
            if (BuildConfig.DEBUG) {
                Log.w(TAG, "FIND REPEAT FROM TAG");
            }
        }

        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        for (Fragment fragment_ : needHideFragments) {
            //if (!fragment_.isHidden()) {
            if (BuildConfig.DEBUG && AppContext.DEBUG_) {
                if (fragment_.isHidden()) {
                    Log.w(TAG, "REPEAT_HIDE_" + fragment_.getClass().getSimpleName());
                } else {

                    Log.w(TAG, "HIDE_" + fragment_.getClass().getSimpleName());
                }
            }
            fragmentTransaction.hide(fragment_);
            if (fragment_.isResumed()) {
                onHiddenNotify.onNotify(fragment_);
            }
//            popBackStackImmediate
            //}
        }
        if (!(currentFragment instanceof MyFragment) && !AppUtils.isPadBySizeLarge(AppContext.getInstance())) {//因为隐藏了actionbar，所以会出现白屏，不能动画
            long currentMs = System.currentTimeMillis();
      /*      if (lastClickTime == 0 || currentMs - lastClickTime > 3000) {
                currentFragment.setEnterTransition(createTransition());
                currentFragment.setReenterTransition(createTransition());
                lastClickTime = currentMs;
                if (BuildConfig.DEBUG) {
                    Log.w(TAG, "_fragment anim:" + currentFragment.getClass().getSimpleName());
                }
            } else {//必须设置，否则依然会因为切换过快导致重复.
                currentFragment.setEnterTransition(null);
                currentFragment.setReenterTransition(null);
            }*/

        }
        if (currentFragment.isAdded()) {
            if (BuildConfig.DEBUG) {
                Log.w(TAG, "FRAGMENT_SHOW:" + currentFragment.getClass().getSimpleName() + ",before_hidden:" + currentFragment.isHidden() + ",save:" + currentFragment.isStateSaved() + ",detach:" + currentFragment.isDetached() + ",add:" + currentFragment.isAdded());
            }
//            fragmentTransaction.remove(currentFragment).commitNowAllowingStateLoss();//  Fragment no longer exists for key f#0: unique id 5893b1ef-2180-4110-ac1a-36ffc36df0b1 viewPager2.setSaveEnabled(false);
            fragmentTransaction.show(currentFragment);

            if (onShowNotify != null && currentFragment.isResumed()) {
                onShowNotify.onNotify(currentFragment);
            }
        } else {
            if (BuildConfig.DEBUG) {
                Log.w(TAG, "FRAGMENT_ADD_NEW :currentStatus:is hidden:" + currentFragment.isHidden() + ",save:" + currentFragment.isStateSaved() + ",detach:" + currentFragment.isDetached() + ",add:" + currentFragment.isAdded() + "," + currentFragment);
            }
            fragmentTransaction.add(fragment_container_id == 0 ? R.id.fragment_space : fragment_container_id, currentFragment, getFragmentTagName(currentFragment.getClass()));
            if (currentFragment.isHidden()) {
                fragmentTransaction.show(currentFragment);
            }
            if (onShowNotify != null && !currentFragment.isResumed()) {
                onShowNotify.onNotify(currentFragment);
            }
        }
        fragmentTransaction.commitAllowingStateLoss();

        return currentFragment;
    }

其实分别屏蔽了2个分支的逻辑，因为同时返回有重叠，但是概率非常低，横竖屏方式无法测试出来，快速点击还是有概率出现 ，所以改成了最终的代码

测试回收的方法非常简单，就是不固定横屏或者竖屏旋转屏幕就可以让activity重建，

在onCreate中 是先添加进去，然后从savedInstanceState 中重新找出来，找到的进行替换。这样保证了顺序问题，

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ArrayMap<Integer, FragmentUtil.PairX<String, SoftReference<Fragment>>> fragments = new ArrayMap<>();


        fragments.put(R.id.navigation_home, pairHome);
        fragments.put(R.id.navigation_app, new FragmentUtil.PairX<String, SoftReference<Fragment>>(AppModuleNewStyleFragment.class.getName(), new SoftReference<>(new AppModuleNewStyleFragment())));
        fragments.put(R.id.navigation_reportform, new FragmentUtil.PairX<String, SoftReference<Fragment>>(ReportFormsFragment.class.getName(), new SoftReference<>(new ReportFormsFragment())));
        fragments.put(R.id.navigation_notifications, new FragmentUtil.PairX<String, SoftReference<Fragment>>(NotificationsFragment.class.getName(), new SoftReference<>(new NotificationsFragment())));
        fragments.put(R.id.navigation_my, new FragmentUtil.PairX<String, SoftReference<Fragment>>(MyFragment.class.getName(), new SoftReference<>(new MyFragment())));

    

    if (savedInstanceState != null) {
        int tab_id = savedInstanceState.getInt("tab_id");
        for (Integer key : fragments.keySet()) {
            Fragment fragment = getSupportFragmentManager().getFragment(savedInstanceState, key + "");
            if (fragment != null) {
                fragments.put(key, new FragmentUtil.PairX<String, SoftReference<Fragment>>(fragment.getClass().getName(), new SoftReference<>(fragment)));
                if (BuildConfig.DEBUG) {
                    Log.w(TAG, "" + fragment.getClass().getName() + "从存储中恢复了");
                }
            }
        }
        binding.navView.setSelectedItemId(tab_id);
    }

在保存状态方法中

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@Override
    protected void onSaveInstanceState(@NonNull Bundle outState) {
        super.onSaveInstanceState(outState);
        Log.w(TAG, "onSaveInstanceState");
        for (Map.Entry<Integer, FragmentUtil.PairX<String, SoftReference<Fragment>>> entry : fragments.entrySet()) {
            FragmentUtil.PairX<String, SoftReference<Fragment>> pair = entry.getValue();
            if (pair.second.get() != null) {
                Fragment fragment = pair.second.get();
                if (fragment != null && fragment.isAdded()) {
                    getSupportFragmentManager().putFragment(outState, entry.getKey() + "", fragment);
                }
            } else {

            }
        }
        outState.putInt("tab_id", getBinding().navView.getSelectedItemId());
    }

PairX类

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public static class PairX<First, Second> {
    public First first;
    public Second second;

    public PairX(First first, Second second) {
        this.first = first;
        this.second = second;
    }
}


我这里用弱引用是为了解决被回收了，但是依然被activity持有的问题，不然我为什么不直接用replace方法呢，replace是我以前常用的方法，然后使用强引用，但是这样不会自动回收replace之前的fragment吧。

重叠的坑很多，我顺便给几个参考链接
各种坑的解决
https://blog.51cto.com/u_15303287/3089390
fragment自身法隐藏解决重叠
https://blog.csdn.net/weixin_33805557/article/details/92344513
https://www.jianshu.com/p/d9143a92ad94