Create fragments and implement fragment switching

app/src/main/java/io/eelo/appinstaller/MainActivity.kt

@@ -6,17 +6,70 @@ import android.support.design.internal.BottomNavigationItemView
 import android.support.design.internal.BottomNavigationMenuView
 import android.support.design.widget.BottomNavigationView
 import android.annotation.SuppressLint
+import android.support.v4.app.Fragment
+import android.view.MenuItem
+import io.eelo.appinstaller.categories.CategoriesFragment
+import io.eelo.appinstaller.home.HomeFragment
+import io.eelo.appinstaller.search.SearchFragment
+import io.eelo.appinstaller.settings.SettingsFragment
+import io.eelo.appinstaller.updates.UpdatesFragment
 import kotlinx.android.synthetic.main.activity_main.*
 
-class MainActivity : AppCompatActivity() {
+class MainActivity : AppCompatActivity(), BottomNavigationView.OnNavigationItemSelectedListener {
+    private var currentFragment: Fragment? = null
+    private val homeFragment = HomeFragment()
+    private val categoriesFragment = CategoriesFragment()
+    private val searchFragment = SearchFragment()
+    private val updatesFragment = UpdatesFragment()
+    private val settingsFragment = SettingsFragment()
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
 
+        // Show the home fragment by default
+        showFragment(homeFragment)
+
+        bottom_navigation_view.setOnNavigationItemSelectedListener(this)
+
+        // Disable shifting of nav bar items
         removeShiftMode(bottom_navigation_view)
     }
 
+    override fun onNavigationItemSelected(item: MenuItem): Boolean {
+        when {
+            item.itemId == R.id.menu_home -> {
+                showFragment(homeFragment)
+                return true
+            }
+            item.itemId == R.id.menu_categories -> {
+                showFragment(categoriesFragment)
+                return true
+            }
+            item.itemId == R.id.menu_search -> {
+                showFragment(searchFragment)
+                return true
+            }
+            item.itemId == R.id.menu_updates -> {
+                showFragment(updatesFragment)
+                return true
+            }
+            item.itemId == R.id.menu_settings -> {
+                showFragment(settingsFragment)
+                return true
+            }
+        }
+        return false
+    }
+
+    private fun showFragment(fragment: Fragment) {
+        supportFragmentManager
+                .beginTransaction()
+                .replace(R.id.frame_layout, fragment)
+                .commit()
+        currentFragment = fragment
+    }
+
     @SuppressLint("RestrictedApi")
     private fun removeShiftMode(bottomNavigationView: BottomNavigationView) {
         val menuView = bottomNavigationView.getChildAt(0) as BottomNavigationMenuView

app/src/main/java/io/eelo/appinstaller/categories/CategoriesFragment.kt

+package io.eelo.appinstaller.categories
+
+import android.os.Bundle
+import android.support.v4.app.Fragment
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import io.eelo.appinstaller.R
+
+class CategoriesFragment : Fragment() {
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        val view = inflater.inflate(R.layout.fragment_categories, container, false)
+        return view
+    }
+}
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app/src/main/java/io/eelo/appinstaller/home/HomeFragment.kt

+package io.eelo.appinstaller.home
+
+import android.os.Bundle
+import android.support.v4.app.Fragment
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import io.eelo.appinstaller.R
+
+class HomeFragment : Fragment() {
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        val view = inflater.inflate(R.layout.fragment_home, container, false)
+        return view
+    }
+}
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app/src/main/java/io/eelo/appinstaller/search/SearchFragment.kt

+package io.eelo.appinstaller.search
+
+import android.os.Bundle
+import android.support.v4.app.Fragment
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import io.eelo.appinstaller.R
+
+class SearchFragment : Fragment() {
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        val view = inflater.inflate(R.layout.fragment_search, container, false)
+        return view
+    }
+}
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app/src/main/java/io/eelo/appinstaller/settings/SettingsFragment.kt

+package io.eelo.appinstaller.settings
+
+import android.os.Bundle
+import android.support.v4.app.Fragment
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import io.eelo.appinstaller.R
+
+class SettingsFragment : Fragment() {
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        val view = inflater.inflate(R.layout.fragment_settings, container, false)
+        return view
+    }
+}
\ No newline at end of file

app/src/main/java/io/eelo/appinstaller/updates/UpdatesFragment.kt

+package io.eelo.appinstaller.updates
+
+import android.os.Bundle
+import android.support.v4.app.Fragment
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import io.eelo.appinstaller.R
+
+class UpdatesFragment : Fragment() {
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        val view = inflater.inflate(R.layout.fragment_updates, container, false)
+        return view
+    }
+}
\ No newline at end of file

app/src/main/res/layout/activity_main.xml

@@ -6,17 +6,25 @@
     android:layout_height="match_parent"
     tools:context=".MainActivity">
 
+    <FrameLayout
+        android:id="@+id/frame_layout"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        app:layout_constraintBottom_toTopOf="@id/divider"
+        app:layout_constraintTop_toTopOf="parent" />
+
     <View
+        android:id="@+id/divider"
         android:layout_width="match_parent"
         android:layout_height="1dp"
         android:background="@color/colorDivider"
-        app:layout_constraintBottom_toTopOf="@id/bottom_navigation_view"/>
+        app:layout_constraintBottom_toTopOf="@id/bottom_navigation_view" />
 
     <android.support.design.widget.BottomNavigationView
         android:id="@+id/bottom_navigation_view"
         android:layout_width="match_parent"
-        app:menu="@menu/activity_main_menu"
+        android:layout_height="wrap_content"
         app:layout_constraintBottom_toBottomOf="parent"
-        android:layout_height="wrap_content"/>
+        app:menu="@menu/activity_main_menu" />
 
 </android.support.constraint.ConstraintLayout>
\ No newline at end of file

app/src/main/res/layout/fragment_categories.xml

+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Categories Fragment"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toTopOf="parent"/>
+
+</android.support.constraint.ConstraintLayout>
\ No newline at end of file

app/src/main/res/layout/fragment_home.xml

+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Home Fragment"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toTopOf="parent"/>
+
+</android.support.constraint.ConstraintLayout>
\ No newline at end of file

app/src/main/res/layout/fragment_search.xml

+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Search Fragment"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toTopOf="parent"/>
+
+</android.support.constraint.ConstraintLayout>
\ No newline at end of file

app/src/main/res/layout/fragment_settings.xml

+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Settings Fragment"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toTopOf="parent"/>
+
+</android.support.constraint.ConstraintLayout>
\ No newline at end of file

app/src/main/res/layout/fragment_updates.xml

+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Updates Fragment"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toTopOf="parent"/>
+
+</android.support.constraint.ConstraintLayout>
\ No newline at end of file