我在Android中玩碎片。
我知道我可以通过使用以下代码更改一个片段:
FragmentManager fragMgr = getSupportFragmentManager();
FragmentTransaction fragTrans = fragMgr.beginTransaction();
MyFragment myFragment = new MyFragment(); //my custom fragment
fragTrans.replace(android.R.id.content, myFragment);
fragTrans.addToBackStack(null);
fragTrans.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
fragTrans.commit();
我的问题是，在Java文件中，如何获得当前显示的片段实例?
当前回答
这是我的工作。我希望这能帮助到某人。
FragmentManager fragmentManager = this.getSupportFragmentManager();
String tag = fragmentManager
.getBackStackEntryAt(
fragmentManager
.getBackStackEntryCount() - 1)
.getName();
Log.d("This is your Top Fragment name: ", ""+tag);
其他回答
Sev的答案适用于当你按下后退按钮或以其他方式更改后退堆栈时。
不过，我做了一些略有不同的事情。我有一个backstack更改监听器设置在一个基本片段和它的派生片段，这段代码是在监听器:
Fragment f = getActivity().getSupportFragmentManager().findFragmentById(R.id.container);
if (f.getClass().equals(getClass())) {
// On back button, or popBackStack(),
// the fragment that's becoming visible executes here,
// but not the one being popped, or others on the back stack
// So, for my case, I can change action bar bg color per fragment
}
请尝试这种方法.....
private Fragment getCurrentFragment(){
FragmentManager fragmentManager = getSupportFragmentManager();
String fragmentTag = fragmentManager.getBackStackEntryAt(fragmentManager.getBackStackEntryCount() - 1).getName();
Fragment currentFragment = getSupportFragmentManager()
.findFragmentByTag(fragmentTag);
return currentFragment;
}
In the main activity, the onAttachFragment(Fragment fragment) method is called when a new fragment is attached to the activity. In this method, you can get the instance of the current fragment. However, the onAttachFragment(Fragment fragment) method is not called when a fragment is popped off the back stack, ie, when the back button is pressed to get the top fragment on top of the stack. I am still looking for a callback method that is triggered in the main activity when a fragment becomes visible inside the activity.
〇应该可以
val visibleFragment = supportFragmentManager.fragments.findLast { fgm -> fgm.isVisible }
Timber.d("backStackIterator: visibleFragment: $visibleFragment")
我用什么来寻找当前显示片段是在下面的代码。这很简单，现在对我来说很有用。它运行在持有片段的活动中
FragmentManager fragManager = this.getSupportFragmentManager();
int count = this.getSupportFragmentManager().getBackStackEntryCount();
Fragment frag = fragManager.getFragments().get(count>0?count-1:count);
