在实例化时将对象传递给Fragment或DialogFragment [英] Passing an Object to Fragment or DialogFragment upon Instantiation

问题描述

我正在尝试找出将对象传递给片段或 DialogFragment 而不会破坏"空构造函数'规则.

I'm trying to work out the correct way to pass in an Object to a Fragment or DialogFragment without breaking the 'empty constructor' rule.

例如，我创建了一个自定义视图，实例化的每个视图都想关联一个DiaglogFragment.此DialogFragment将用于显示控件，用户可以使用这些控件更改与之关联的自定义视图的某些方面.因为View是我所了解的对象，所以我不能使用 setArguments().

For example I have created a custom View and for each one I instantiate I want to associate a DiaglogFragment. This DialogFragment will be used to display controls with which the user can alter certain aspects of the custom View it is associated with. Because View is an Object I understand I cannot use setArguments().

我可以实现DialogFragment的newInstance(View)方法(即工厂模式)，但是如果我的Fragment由系统保存然后在以后恢复，会发生什么情况?据我所知，将没有对View对象的引用?

I could implement a newInstance(View) method of my DialogFragment i.e. Factory pattern but then what happens if my Fragment is saved by the system and then restored at a later date? As far as I can tell there will be no reference to the View object?

有人可以告诉我我是否以错误的方式使用了Fragments，或者是否有办法实现将对象传递给Fragment，这也将在以后处理系统时对付它.

Could someone tell me if I am using Fragments in the wrong way or is there way to achieve passing in an object to the Fragment which will also cope with the system reconstructing it at a later time.

推荐答案

在您的 DialogFragmnet 类中，创建两个方法:

In your DialogFragmnet class, you create two methods:

1. newInstance 来创建您的 DialogFragment

设置初始化您的对象

并在 onCreate

public class YourDialogFragment extends DialogFragment {

    ComplexVariable complexVar;

    public static YourDialogFragment newInstance(int arg, ComplexVariable complexVar) {
        YourDialogFragment frag = new MoveSongDialogFragment();
        Bundle args = new Bundle();
        args.putInt("count", arg);
        frag.setArguments(args);
        frag.setComplexVariable(complexVar);
        return frag;
    }

    public void setComplexVariable(ComplexVariable complexVar) {
        this.complexVar = complexVar;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setRetainInstance(true);
    }
}

然后，显示对话框

FragmentManager manager = getSupportFragmentManager();
FragmentTransaction ft = manager.beginTransaction();

Fragment prev = manager.findFragmentByTag("yourTag");
if (prev != null) {
    ft.remove(prev);
}

// Create and show the dialog.
DialogFragment newFragment = YourFragmentDialog.newInstance(argument, yourComplexObject);
newFragment.show(ft, "yourTag");

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