片段上的导航视图句柄后退按钮 [英] Navigation view handle back button on fragment

问题描述

我需要处理片段上的后退按钮.我在移动应用程序上使用了导航.问题是打开新片段页面时如何处理后退按钮?

Hi I need to handle back button on fragment. I using this navigation on my mobile apps. The question is how to handle back button when I open new fragment page?

我尝试在新片段上使用以下代码.

I try using below code on new fragment.

  actionBar.setDisplayShowHomeEnabled(true);
  actionBar.setDisplayHomeAsUpEnabled(true);

但是，当单击后退"按钮时，导航将打开.有解决方案吗?

But when click the back button , the navigation will be open. Any solution ?

谢谢

推荐答案

您知道，每当用户按下Back按钮时，您都需要转到先前加载的片段，然后尝试执行此操作(请注意，片段必须添加transaction.addToBackStack(null);)

As you know whenever user presses Back button you need to go to the previously loaded fragment and to do that try this (note fragment must be added with transaction.addToBackStack(null);)

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    if (item.getItemId() == android.R.id.home) {
        int backStackCount = fragmentManager.getBackStackEntryCount();//check currently how many frags loaded
        if (backStackCount > 0) {
            fragmentManager.popBackStack(); //go back to previously loaded fragment
        }   
    }

    return super.onOptionsItemSelected(item);
}

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