如何正确使用片段 [英] How to correctly using fragments

问题描述

在我的基类的活动我有联系，我从菜单中调用所有片段。

In my base Activity class I have links to all fragments that I call from menu.

事情是这样的：

BaseFragment mProjects;
BaseFragment mProfile;

public BaseFragment getFragment(FragmentType type) {
        BaseFragment fr = null;
        switch (type) {
            case PROFILE:
                fr = new Profile();
                break;
            case PROJECTS:
                fr = new Projects();
                break;
            default:
                return null;
        }

        return fr;
    }

所以，我创建片段从菜单有一次，访问的实例。好吗？或者我应该创建片段每次？如果是这样，那我怎么才能救片段的状态（数据位）？因为当我使用替换从片段经理，的onSaveInstanceState 替换片段不叫。所以，当我将重新打开它，没有保存的状态。

So, i create instance of fragments that accessible from menu one time. Is it good? Or i should create fragment every time? If so, then how can i save state of fragment (data, position)? Cause when i use replace from fragment manager, onSaveInstanceState of replaced fragment doesn't called. So when i will reopen it, there is no saved state.

顺便说一句，我使用的onSaveInstanceState 的活动：

Btw, I'm using onSaveInstanceState in Activity:

@Override
public void onSaveInstanceState(Bundle saveInstanceState) {

    // doing things
    super.onSaveInstanceState(saveInstanceState);
}

无论如何，如果我不存储链接片段的onSaveInstanceState 片段将永远不会被调用。所以，我可以存储片段的状态的onPause 方法，但似乎不好解决。

Anyway if i don't store links to fragments onSaveInstanceState of fragment will never called. So, i can store state of fragment in onPause method, but it seems bad solution.

UPD：它不是基于观点的问题。应该有使用片段的最佳做法。所以我要求这一点。

UPD: it's not opinion based question. There should be best practice for using fragment. So i asked for this.

推荐答案

在您更换当前显示的片段，需要 getSupportFragmentManager（）。putFragment（束，弦乐，片段），这将存储片段成束，你可以保持一个参考，并保存到您的活动的实例状态。

Before you replace a currently shown fragment, you need to getSupportFragmentManager().putFragment(Bundle, String, Fragment), this will store that fragment into a Bundle which you can keep a reference to, and save to your activity's instance state.

在你的 getFragment 方法，首先查看，如果你一直保存碎片进入包包含你要创建的片段 - getSupportFragmentManager （）.getFragment（捆绑，字符串）。这会给你，你可以返回并更换一个片段。如果没有，创建片段的新实例，你目前是。

In your getFragment method, first check to see if the bundle you have been saving your fragments into contains the fragment you want to create - getSupportFragmentManager().getFragment(Bundle, String). This will give you a fragment you can return and replace. If not, create a new instance of the fragment as you currently are.

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