如何使向上按钮返回而不是打开导航抽屉 [英] How to make Up Button go back instead of opening Navigation Drawer

问题描述

我在我的应用程序中成功实现了导航抽屉，将菜单的每个项目链接到一个片段.目标片段隐藏了DrawerToggle并显示了向上按钮(即箭头图标)，但是由于任何原因，如果我单击它，它将打开抽屉，而我无法返回上一个片段.我必须按下后退"按钮来执行此操作.我该如何改变这种行为?是否可以解决此问题而无需在每个片段中添加代码?

I successfully implemented a Navigation Drawer in my app, linking each item of the menu to a fragment. The destination fragment hides the DrawerToggle and displays the up button (i.e. the arrow icon), but for whatever reason, if I click on it, it opens the drawer and I can't go back to the previous fragment. I have to press the back button to do it. How can I change this behaviour? Is it possible to solve this without adding code in every fragment?

我使用的是什么

• 导航组件
• 一项活动，一些碎片
• 工具栏
• AppBarConfiguration

MainActivity

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        // Setup FTUE conditional navigation
        setupNavigation()

        setupNavigationDrawer()

        appBarConfiguration =
            AppBarConfiguration(
                setOf(R.id.overviewFragment, R.id.registrationFragment,
                       R.id.registrationParamFragment), drawerLayout)
        setupActionBarWithNavController(navController, appBarConfiguration)
        findViewById<NavigationView>(R.id.nav_view)
            .setupWithNavController(navController)
    }

    /**
     * Set the toolbar, set the drawerLayout, set the drawerToggle
     */
    private fun setupNavigationDrawer() {
        toolbar = findViewById(R.id.toolbar)

        setSupportActionBar(toolbar)

        drawerLayout = (findViewById<DrawerLayout>(R.id.drawer_layout))
            .apply {
                setStatusBarBackground(R.color.colorPrimaryDark)
            }
        drawerToggle = ActionBarDrawerToggle(this, drawerLayout, toolbar, R.string.open, R.string.close)
        drawerToggle.setDrawerIndicatorEnabled(true)
        drawerToggle.syncState()

        drawerLayout.addDrawerListener(drawerToggle)

    }

    override fun onPostCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) {
        super.onPostCreate(savedInstanceState, persistentState)
        drawerToggle.syncState()
    }

    /**
     * Ensures that the drawer is closed
     * before the app switches back to the previous fragment
     */
    override fun onBackPressed() {
        if (drawerLayout.isDrawerOpen(GravityCompat.START)) {
            drawerLayout.closeDrawer(GravityCompat.START)
        } else {
            super.onBackPressed()
        }
    }
}

完整存储库: Github

推荐答案

您需要使用导航控制器设置工具栏:

You need to set your toolbar up with the nav controller:

toolbar.setupWithNavController(findNavController(R.id.nav_host_fragment),findViewById(R.id.full_drawer_layout))

此处有更多信息.

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