vahid-m · September 17, 2024 11:07 · Sep 17, 2024
diff --git a/BottomNavFragment.kt b/BottomNavFragment.kt
@@ -0,0 +1,86 @@
+class RootFragment: KeyedFragment(R.layout.root_fragment) {
+    private val binding by viewBinding(RootFragmentBinding::bind)
+
+    private lateinit var firstFragment: FirstFragment
+    private lateinit var secondFragment: SecondFragment
+    private lateinit var thirdFragment: ThirdFragment
+
+    private val fragments: Array<Fragment> get() = arrayOf(firstFragment, secondFragment, thirdFragment)
+    private var selectedIndex = 0
+
+    private val tabs: Array<TextView> get() = binding.run {
+        arrayOf(buttonFirstTab, buttonSecondTab, buttonThirdTab)
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        if (savedInstanceState == null) {
+            val firstFragment = FirstFragment().also { this.firstFragment = it }
+            val secondFragment = SecondFragment().also { this.secondFragment = it }
+            val thirdFragment = ThirdFragment().also { this.thirdFragment = it }
+
+            childFragmentManager.beginTransaction()
+                .add(R.id.containerBottomNavContent, firstFragment, "firstFragment")
+                .add(R.id.containerBottomNavContent, secondFragment, "secondFragment")
+                .add(R.id.containerBottomNavContent, thirdFragment, "thirdFragment")
+                .selectFragment(selectedIndex)
+                .commit()
+        } else {
+            selectedIndex = savedInstanceState.getInt("selectedIndex", 0)
+
+            firstFragment = childFragmentManager.findFragmentByTag("firstFragment") as FirstFragment
+            secondFragment = childFragmentManager.findFragmentByTag("secondFragment") as SecondFragment
+            thirdFragment = childFragmentManager.findFragmentByTag("thirdFragment") as ThirdFragment
+        }
+    }
+
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+
+        tabs.forEachIndexed { index, textView ->
+            textView.setOnClickListener {
+                selectFragment(index)
+            }
+        }
+
+        setupTabSelectedState(selectedIndex)
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        super.onSaveInstanceState(outState)
+        outState.putInt("selectedIndex", selectedIndex)
+    }
+
+    private fun FragmentTransaction.selectFragment(selectedIndex: Int): FragmentTransaction {
+        fragments.forEachIndexed { index, fragment ->
+            if (index == selectedIndex) {
+                attach(fragment)
+            } else {
+                detach(fragment)
+            }
+        }
+
+        return this
+    }
+
+    private fun setupTabSelectedState(selectedIndex: Int) {
+        tabs.forEachIndexed { index, textView ->
+            textView.setTextColor(when {
+                index == selectedIndex -> ContextCompat.getColor(requireContext(), R.color.tab_selected)
+                else -> ContextCompat.getColor(requireContext(), R.color.tab_unselected)
+            })
+        }
+    }
+
+    private fun selectFragment(indexToSelect: Int) {
+        this.selectedIndex = indexToSelect
+
+        setupTabSelectedState(indexToSelect)
+
+        childFragmentManager.beginTransaction()
+            .selectFragment(indexToSelect)
+            .commit()
+    }
+}