在android中管理工具栏的导航和从片段到片段的后退按钮 [英] Manage toolbar's navigation and back button from fragment to fragment in android

问题描述

我的所有片段都通过 ActionBarActivity （ mainActivity ）进行控制，在 mainActivity 内 DrawerLayout 已实现，并且所有子片段都通过drawerLayout的列表项单击进行推送。我面临的问题是在通过抽屉推送片段之后我想将抽屉图标更改为 ToolBar 的后退图标，以便用户可以导航到上一个片段并处理android.R.id.home的回调要么在同一个片段内，要么在 mainActivity 内。

All of my fragments are controlled through ActionBarActivity (mainActivity), inside mainActivity a DrawerLayout is implemented and all the child fragments are pushed through drawerLayout's list item click. The problem that I'm facing is after pushing a fragment through drawerLayout I want to change the drawer icon into back icon of ToolBar so that user can navigate to previous fragment and to handle the callback of android.R.id.home either inside the same fragment or inside the mainActivity.

推荐答案

您已将 Fragment 添加到后台堆栈，并在片段管理器中添加侦听器，如下所示

You have add Fragment to back stack and add listener in fragment manager like this

getSupportFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
            @Override
            public void onBackStackChanged() {
                if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
                    getSupportActionBar().setDisplayHomeAsUpEnabled(true); // show back button
                    toolbar.setNavigationOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            onBackPressed();
                        }
                    });
                } else {
                    //show hamburger
                    getSupportActionBar().setDisplayHomeAsUpEnabled(false);
                    toggle.syncState();
                    toolbar.setNavigationOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            drawerLayout.openDrawer(GravityCompat.START);
                        }
                    });
                }
            }
        });

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