解决Activity被系统销毁造成的Fragment混乱的问题

最新推荐文章于 2021-05-31 03:07:38 发布

原创最新推荐文章于 2021-05-31 03:07:38 发布 · 2.8k 阅读

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本文介绍了一种在Android中解决Activity因内存紧张被销毁后重建时Fragment显示混乱的问题的方法。通过保存和恢复Fragment的状态来确保界面的一致性。

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当activity被系统因为内存紧张销毁时再重建时，内部的fragment可能会导致显示混乱，尤其是一个activity加多个fragment的界面。
解决办法就是判断savedInstanceState是否为Null，并进行恢复，示例代码如下：

    private int saveIndex;//保存的fragment的下标
    private boolean isHomeActDestroy;//activity的销毁标识

     @Override
    protected void onCreate(@Nullable Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        if(savedInstanceState!=null&&savedInstanceState.getBoolean("isHomeActDestroy",false)){

            saveIndex = savedInstanceState.getInt("SaveIndex", 0);
            isHomeActDestroy=savedInstanceState.getBoolean("isHomeActDestroy",false);

            FragmentManager manager = getSupportFragmentManager();
            FragmentTransaction transaction = manager.beginTransaction();
            Fragment f1 = manager.findFragmentByTag(MapFg.class.getSimpleName());
            Fragment f2 = manager.findFragmentByTag(ShopFg.class.getSimpleName());
            Fragment f3 = manager.findFragmentByTag(PublishFg.class.getSimpleName());
            Fragment f4 = manager.findFragmentByTag(AroundFg.class.getSimpleName());
            Fragment f5 = manager.findFragmentByTag(UserFg.class.getSimpleName());
            switch (saveIndex){
                case 0:
                {
                    if (null==f1){
                        transaction.add(R.id.fragment_container,new MapFg(),MapFg.class.getSimpleName());
                    }else {
                        transaction.show(f1);
                    }
                    if (null!=f2)
                        transaction.hide(f2);
                    if (null!=f3)
                        transaction.hide(f3);
                    if (null!=f4)
                        transaction.hide(f4);
                    if (null!=f5)
                        transaction.hide(f5);
                    transaction.commitAllowingStateLoss();
                }
                    break;
                case 1:
                {
                    if (null==f2){
                        transaction.add(R.id.fragment_container,new ShopFg(),ShopFg.class.getSimpleName());
                    }else {
                        transaction.show(f2);
                    }
                    if (null!=f1)
                        transaction.hide(f1);
                    if (null!=f3)
                        transaction.hide(f3);
                    if (null!=f4)
                        transaction.hide(f4);
                    if (null!=f5)
                        transaction.hide(f5);
                    transaction.commitAllowingStateLoss();
                }
                break;
                //                    case 2:
                //                        break;
                case 3:
                {
                    if (null==f4){
                        transaction.add(R.id.fragment_container,new AroundFg(),AroundFg.class.getSimpleName());
                    }else {
                        transaction.show(f4);
                    }
                    if (null!=f1)
                        transaction.hide(f1);
                    if (null!=f2)
                        transaction.hide(f2);
                    if (null!=f3)
                        transaction.hide(f3);
                    if (null!=f5)
                        transaction.hide(f5);
                    transaction.commitAllowingStateLoss();
                }
                break;
                case 4:
                {
                    if (null==f5){
                        transaction.add(R.id.fragment_container,new UserFg(),UserFg.class.getSimpleName());
                    }else {
                        transaction.show(f5);
                    }
                    if (null!=f1)
                        transaction.hide(f1);
                    if (null!=f2)
                        transaction.hide(f2);
                    if (null!=f3)
                        transaction.hide(f3);
                    if (null!=f4)
                        transaction.hide(f4);
                    transaction.commitAllowingStateLoss();
                }
                break;
                default:
            }
        }
        setContentView(R.layout.act_home);
        if (savedInstanceState == null){
            getSupportFragmentManager().beginTransaction().add(R.id.fragment_container,new MapFg(),MapFg.class.getSimpleName()).commit();
        }
        ///此处其他代码省略
     }
       @Override
    protected void onSaveInstanceState(Bundle outState)
    {
        outState.putInt("SaveIndex", saveIndex);
        outState.putBoolean("isHomeActDestroy",true);
        super.onSaveInstanceState(outState);
    }