Android的碎片处理后退按钮preSS [英] Android Fragment handle back button press

问题描述

我有一些片段在我的活动

I have some fragments in my activity

[1], [2], [3], [4], [5], [6]

和上后退按钮preSS我必须从返回[2] [1]，如果当前的活动片段[2]，或者什么也不做，否则。

And on Back Button Press I must to return from [2] to [1] if current active fragment is [2], or do nothing otherwise.

什么是做到这一点的最佳做法？

What is the best practise to do that?

修改：应用程序不能返回[2] [3] ... [6]

EDIT: Application must not return to [2] from [3]...[6]

推荐答案

当您在片段之间的转换，呼叫 addToBackStack（）为你的 FragmentTransaction ：

When you are transitioning between Fragments, call addToBackStack() as part of your FragmentTransaction:

FragmentTransaction tx = fragmentManager.beginTransation();
tx.replace( R.id.fragment, new MyFragment() ).addToBackStack( "tag" ).commit();

如果您需要更详细的控制（即当一些片段可见，要想喝preSS返回键），你可以在父设置 OnKeyListener 鉴于您的片段：

If you require more detailed control (i.e. when some Fragments are visible, you want to suppress the back key) you can set an OnKeyListener on the parent view of your fragment:

//You need to add the following line for this solution to work; thanks skayred
fragment.getView().setFocusableInTouchMode(true);
fragment.getView().requestFocus();
fragment.getView().setOnKeyListener( new OnKeyListener()
{
    @Override
    public boolean onKey( View v, int keyCode, KeyEvent event )
    {
        if( keyCode == KeyEvent.KEYCODE_BACK )
        {
            return true;
        }
        return false;
    }
} );

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