improves fragment handling and fragment transactions

Author: stefanmedack

app/src/main/java/de/stefanmedack/ccctv/ui/detail/DetailActivity.kt

@@ -13,6 +13,7 @@ import de.stefanmedack.ccctv.ui.base.BaseInjectableActivity
 import de.stefanmedack.ccctv.util.EVENT_ID
 import de.stefanmedack.ccctv.util.EVENT_PICTURE
 import de.stefanmedack.ccctv.util.SHARED_DETAIL_TRANSITION
+import de.stefanmedack.ccctv.util.replaceFragmentInTransaction
 
 class DetailActivity : BaseInjectableActivity() {
 
@@ -27,15 +28,13 @@ class DetailActivity : BaseInjectableActivity() {
         // prevent stand-by while playing videos
         window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
 
-        if (savedInstanceState == null) {
-            fragment = DetailFragment()
-            fragment?.arguments = Bundle(2).apply {
+        fragment = DetailFragment()
+        fragment?.let { frag ->
+            frag.arguments = Bundle(2).apply {
                 putInt(EVENT_ID, intent.getIntExtra(EVENT_ID, -1))
                 putString(EVENT_PICTURE, intent.getStringExtra(EVENT_PICTURE))
             }
-            supportFragmentManager.beginTransaction().replace(R.id.fragment, fragment, DETAIL_TAG).commit()
-        } else {
-            fragment = supportFragmentManager.findFragmentByTag(DETAIL_TAG) as DetailFragment
+            replaceFragmentInTransaction(frag, R.id.fragment, DETAIL_TAG)
         }
     }
 

app/src/main/java/de/stefanmedack/ccctv/ui/main/MainActivity.kt

@@ -4,6 +4,7 @@ import android.os.Bundle
 import android.view.KeyEvent
 import de.stefanmedack.ccctv.R
 import de.stefanmedack.ccctv.ui.base.BaseInjectableActivity
+import de.stefanmedack.ccctv.util.replaceFragmentInTransaction
 
 class MainActivity : BaseInjectableActivity() {
 
@@ -15,11 +16,9 @@ class MainActivity : BaseInjectableActivity() {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.fragment_activity)
 
-        if (savedInstanceState == null) {
-            fragment = MainFragment()
-            supportFragmentManager.beginTransaction().replace(R.id.fragment, fragment).commit()
-        } else {
-            fragment = supportFragmentManager.findFragmentByTag(MAIN_TAG) as MainFragment
+        fragment = supportFragmentManager.findFragmentByTag(MAIN_TAG) as? MainFragment ?: MainFragment()
+        fragment?.let { frag ->
+            replaceFragmentInTransaction(frag, R.id.fragment, MAIN_TAG)
         }
     }
 

app/src/main/java/de/stefanmedack/ccctv/ui/playback/ExoPlayerActivity.kt

@@ -6,6 +6,7 @@ import android.support.v4.app.FragmentActivity
 import android.view.WindowManager
 import de.stefanmedack.ccctv.R
 import de.stefanmedack.ccctv.util.STREAM_URL
+import de.stefanmedack.ccctv.util.addFragmentInTransaction
 import info.metadude.java.library.brockman.models.Stream
 import info.metadude.java.library.brockman.models.Url.TYPE
 
@@ -18,14 +19,12 @@ class ExoPlayerActivity : FragmentActivity() {
         // prevent stand-by while playing videos
         window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
 
-        val ft = supportFragmentManager.beginTransaction()
         val fragment = ExoPlayerFragment().apply {
             arguments = Bundle(1).also {
                 it.putString(STREAM_URL, intent.getStringExtra(STREAM_URL))
             }
         }
-        ft.add(R.id.videoFragment, fragment, ExoPlayerFragment.TAG)
-        ft.commit()
+        addFragmentInTransaction(fragment, R.id.videoFragment, ExoPlayerFragment.TAG)
     }
 
     override fun onVisibleBehindCanceled() {

app/src/main/java/de/stefanmedack/ccctv/ui/search/SearchActivity.kt

@@ -4,6 +4,7 @@ import android.content.Intent
 import android.os.Bundle
 import de.stefanmedack.ccctv.R
 import de.stefanmedack.ccctv.ui.base.BaseInjectableActivity
+import de.stefanmedack.ccctv.util.replaceFragmentInTransaction
 
 class SearchActivity : BaseInjectableActivity() {
 
@@ -15,11 +16,9 @@ class SearchActivity : BaseInjectableActivity() {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.fragment_activity)
 
-        if (savedInstanceState == null) {
-            fragment = SearchFragment()
-            supportFragmentManager.beginTransaction().replace(R.id.fragment, fragment).commit()
-        } else {
-            fragment = supportFragmentManager.findFragmentByTag(SEARCH_TAG) as SearchFragment
+        fragment = supportFragmentManager.findFragmentByTag(SEARCH_TAG) as? SearchFragment ?: SearchFragment()
+        fragment?.let { frag ->
+            replaceFragmentInTransaction(frag, R.id.fragment, SEARCH_TAG)
         }
     }
 

app/src/main/java/de/stefanmedack/ccctv/util/AndroidExtensions.kt

@@ -4,6 +4,10 @@ import android.app.Activity
 import android.content.pm.PackageManager.PERMISSION_GRANTED
 import android.support.v17.leanback.widget.ArrayObjectAdapter
 import android.support.v17.leanback.widget.Row
+import android.support.v4.app.Fragment
+import android.support.v4.app.FragmentActivity
+import android.support.v4.app.FragmentManager
+import android.support.v4.app.FragmentTransaction
 
 fun Activity.hasPermission(permission: String) : Boolean =
         PERMISSION_GRANTED == this.packageManager.checkPermission(permission, this.packageName)
@@ -12,4 +16,34 @@ operator fun ArrayObjectAdapter.plusAssign(items: List<*>?) {
     items?.forEach { this.add(it) }
 }
 
-operator fun ArrayObjectAdapter.plusAssign(row: Row) = this.add(row)
+operator fun ArrayObjectAdapter.plusAssign(row: Row) = this.add(row)
+
+inline fun FragmentManager.inTransaction(func: FragmentTransaction.() -> FragmentTransaction) {
+    beginTransaction().func().commit()
+}
+
+fun FragmentActivity.addFragmentInTransaction(
+        fragment: Fragment,
+        containerId: Int,
+        tag: String? = null,
+        addToBackStack: Boolean = false
+) {
+    supportFragmentManager.inTransaction {
+        add(containerId, fragment, tag).also {
+            if (addToBackStack) addToBackStack(tag)
+        }
+    }
+}
+
+fun FragmentActivity.replaceFragmentInTransaction(
+        fragment: Fragment,
+        containerId: Int,
+        tag: String? = null,
+        addToBackStack: Boolean = false
+) {
+    supportFragmentManager.inTransaction {
+        replace(containerId, fragment, tag).also {
+            if (addToBackStack) addToBackStack(tag)
+        }
+    }
+}