我有多个片段。我想保存所有实例，直到再次按下“主页”按钮

Question

我尝试了许多方法来保存实例，但是我很困惑如何将实例保存在背包中，因为没有人描述了如果有多个片段。

bottomNavigationView.setOnItemSelectedListener(item -> {
    switch (item.getItemId()){
            case R.id.home:
                loadFragment(new HomeFragment(),0);
                break;

        case R.id.create:

      loadFragment(new CreateFragment(),1);
            break;

        case R.id.profile:
            loadFragment(new ProfileFragment(),1);
            break;
    }
    return true;
});

    public void loadFragment(Fragment fragment,int flag){
        FragmentManager fragmentManager=getSupportFragmentManager();
        FragmentTransaction fragmentTransaction=fragmentManager.beginTransaction();
        if(flag==0){
            fragmentTransaction.add(R.id.frame_layout,fragment);
            fragmentManager.popBackStack(ROOT_FRAGMENT_TAG,FragmentManager.POP_BACK_STACK_INCLUSIVE);
                fragmentTransaction.addToBackStack(ROOT_FRAGMENT_TAG);
        }
        else {
            fragmentTransaction.replace(R.id.frame_layout,fragment);
            fragmentTransaction.addToBackStack(null);
        }
        fragmentTransaction.commit();
    }

Answer 1

我建议您将片段班级班。

private static MyFragment fragment;


public static MyFragment getInstance() {
    if (fragment == null) {
        fragment = new MyFragment();
    }
    return fragment;
}

然后使用getInstance（）方法来实例化片段