带片段的操作栏向上导航 [英] actionbar up navigation with fragments

问题描述

我有一个选项卡式操作栏/viewpager 布局，其中包含三个选项卡:A、B 和 C.在选项卡 C 选项卡(片段)中，我添加了另一个片段说片段 D.与

I have a tabbed Actionbar/viewpager layout with three tabs say A, B, and C. In tab C tab(fragment),I am adding another fragment say fragment D. with

 DFragment f= new DFragment();
 ft.add(android.R.id.content, f, "");
 ft.remove(CFragment.this);
 ft.addToBackStack(null);
 ft.commit();

我修改了 DFragment 的 onResume 中的 actionbar 来添加按钮:

I modify actionbar in DFragment's onResume to add up button:

ActionBar ab = getActivity().getActionBar();
ab.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
ab.setDisplayHomeAsUpEnabled(true);
ab.setDisplayShowHomeEnabled(true);

现在在 DFragment 中，当我按下硬件(电话)后退按钮时，我返回到选择了 CFragment 的原始选项卡式(ABC)布局.如何使用操作栏向上按钮实现此功能?

Now in DFragment, when I press hardware(phone) Back button, I return to the original Tabbed(ABC) layout with CFragment selected. How can I achieve this functionality with actionbar up button?

推荐答案

实施 OnBackStackChangedListener 并将此代码添加到您的 Fragment Activity.

Implement OnBackStackChangedListener and add this code to your Fragment Activity.

@Override
public void onCreate(Bundle savedInstanceState) {
    //Listen for changes in the back stack
    getSupportFragmentManager().addOnBackStackChangedListener(this);
    //Handle when activity is recreated like on orientation Change
    shouldDisplayHomeUp();
}

@Override
public void onBackStackChanged() {
    shouldDisplayHomeUp();
}

public void shouldDisplayHomeUp(){
   //Enable Up button only  if there are entries in the back stack
   boolean canGoBack = getSupportFragmentManager().getBackStackEntryCount()>0;
   getSupportActionBar().setDisplayHomeAsUpEnabled(canGoBack);
}

@Override
public boolean onSupportNavigateUp() {
    //This method is called when the up button is pressed. Just the pop back stack.
    getSupportFragmentManager().popBackStack();
    return true;
}

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