动作条向上导航与片段 [英] actionbar up navigation with fragments

问题描述

我已经有三个选项卡的标签式动作条/ viewpager布局说的 A B 和 C 。在标签的 C 标签（片段），我加入另一个片段说的片段ð。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();

我修改动作条在DFragment的onResume加起来按钮：

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，当我preSS硬件（手机）后退按钮，我要回去与CFragment原来的选项卡式（ABC）的布局选择。我怎样才能实现这个功能与动作条向上按钮了吗？

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 并添加此code到你的片段活动。

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 canback = getSupportFragmentManager().getBackStackEntryCount()>0;
   getSupportActionBar().setDisplayHomeAsUpEnabled(canback);
}

@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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