android - 错误：类型不匹配：推断类型为单位，但预期为布尔值

Question

我在导航抽屉中有错误。我在片段（center_fragment）上的抽屉不工作！

  navigationView.setNavigationItemSelectedListener {
            drawerLayout.closeDrawers()

            when (it.itemId) {

                R.id.contact -> findNavController().navigate(
                    centerFragmentDirections.actionCenterFragmentToContactFragment()

                )

                R.id.about_us -> findNavController().navigate(
                    centerFragmentDirections.actionCenterFragmentToAboutFragment()

                )


                else -> true
            }

标签： androidkotlinnavigationdrawer

Answer 1

setNavigationItemSelectedListener期望您返回布尔值，但您没有在 2 个when分支中返回布尔值：

        navView.setNavigationItemSelectedListener {
            when (it.itemId) {
                R.id.contact -> {
                    findNavController().navigate(centerFragmentDirections.actionCenterFragmentToContactFragment())
                    return@setNavigationItemSelectedListener true
                }
                R.id.about_us -> {
                    findNavController().navigate(centerFragmentDirections.actionCenterFragmentToAboutFragment())
                    return@setNavigationItemSelectedListener true
                }
                else -> true
            }
        }