优化首页切换 Fragment Kotlin 的用法；

Author: git-xuhao

app/build.gradle

@@ -20,8 +20,8 @@ android {
         applicationId "com.hazz.kotlinmvp"
         minSdkVersion rootProject.ext.android.minSdkVersion
         targetSdkVersion rootProject.ext.android.targetSdkVersion
-        versionCode 4
-        versionName "1.2.1"
+        versionCode 5
+        versionName "1.2.2"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
         javaCompileOptions {
             annotationProcessorOptions {

app/src/main/java/com/hazz/kotlinmvp/ui/activity/MainActivity.kt

@@ -36,7 +36,7 @@ class MainActivity : BaseActivity() {
     private var mHomeFragment: HomeFragment? = null
     private var mDiscoveryFragment: DiscoveryFragment? = null
     private var mHotFragment: HotFragment? = null
-    private var mMineFragment: MineFragment?=null
+    private var mMineFragment: MineFragment? = null
 
     //默认为0
     private var mIndex = 0
@@ -58,7 +58,6 @@ class MainActivity : BaseActivity() {
     }
 
 
-
     //初始化底部菜单
     private fun initTab() {
         (0 until mTitles.size)
@@ -84,40 +83,33 @@ class MainActivity : BaseActivity() {
     private fun switchFragment(position: Int) {
         val transaction = supportFragmentManager.beginTransaction()
         hideFragments(transaction)
-        showToast(supportFragmentManager.fragments.size.toString())
-        /*重复进入退出视频详情页会导致fragment不断增加*/
         when (position) {
-            0 //首页
-            -> if (mHomeFragment == null) {
-
-                mHomeFragment = HomeFragment.getInstance(mTitles[position])
-                transaction.add(R.id.fl_container, mHomeFragment, "home")
-            } else {
-                transaction.show(mHomeFragment)
-            }
-            1 //发现
-            -> if (mDiscoveryFragment == null) {
-                mDiscoveryFragment = DiscoveryFragment.getInstance(mTitles[position])
-                transaction.add(R.id.fl_container, mDiscoveryFragment, "discovery")
-            } else {
-                transaction.show(mDiscoveryFragment)
+            0 // 首页
+            -> mHomeFragment?.let {
+                transaction.show(it)
+            } ?: HomeFragment.getInstance(mTitles[position]).let {
+                mHomeFragment = it
+                transaction.add(R.id.fl_container, it, "home")
             }
-            2 //热门
-            -> if ( mHotFragment == null) {
-                mHotFragment = HotFragment.getInstance(mTitles[position])
-                transaction.add(R.id.fl_container, mHotFragment, "hot")
-            }
-            else {
-                transaction.show(mHotFragment)
-            }
-
+            1  //发现
+            -> mDiscoveryFragment?.let {
+                transaction.show(it)
+            } ?: DiscoveryFragment.getInstance(mTitles[position]).let {
+                mDiscoveryFragment = it
+                transaction.add(R.id.fl_container, it, "discovery") }
+            2  //热门
+            -> mHotFragment?.let {
+                transaction.show(it)
+            } ?: HotFragment.getInstance(mTitles[position]).let {
+                mHotFragment = it
+                transaction.add(R.id.fl_container, it, "hot") }
             3 //我的
-            -> if (mMineFragment == null) {
-                mMineFragment = MineFragment.getInstance(mTitles[position])
-                transaction.add(R.id.fl_container, mMineFragment, "mine")
-            } else {
-                transaction.show(mMineFragment)
-            }
+            -> mMineFragment?.let {
+                transaction.show(it)
+            } ?: MineFragment.getInstance(mTitles[position]).let {
+                mMineFragment = it
+                transaction.add(R.id.fl_container, it, "mine") }
+
             else -> {
 
             }
@@ -134,19 +126,10 @@ class MainActivity : BaseActivity() {
      * @param transaction transaction
      */
     private fun hideFragments(transaction: FragmentTransaction) {
-        if (null != mHomeFragment) {
-            transaction.hide(mHomeFragment)
-        }
-        if (null != mDiscoveryFragment) {
-            transaction.hide(mDiscoveryFragment)
-        }
-        if (null != mHotFragment) {
-            transaction.hide(mHotFragment)
-        }
-        if (null != mMineFragment) {
-            transaction.hide(mMineFragment)
-        }
-
+        mHomeFragment?.let { transaction.hide(it) }
+        mDiscoveryFragment?.let { transaction.hide(it) }
+        mHotFragment?.let { transaction.hide(it) }
+        mMineFragment?.let { transaction.hide(it) }
     }
 
 
@@ -166,6 +149,7 @@ class MainActivity : BaseActivity() {
     override fun initData() {
 
     }
+
     override fun start() {
 
     }
@@ -186,5 +170,4 @@ class MainActivity : BaseActivity() {
     }
 
 
-
 }

app/src/main/java/com/hazz/kotlinmvp/view/recyclerview/adapter/CommonAdapter.kt

@@ -16,7 +16,7 @@ import com.hazz.kotlinmvp.view.recyclerview.ViewHolder
 
 abstract class CommonAdapter<T>(var mContext: Context, var mData: ArrayList<T>, //条目布局
                                 private var mLayoutId: Int) : RecyclerView.Adapter<ViewHolder>() {
-    protected var mInflater: LayoutInflater?=null
+    protected var mInflater: LayoutInflater? = null
     private var mTypeSupport: MultipleType<T>? = null
 
     //使用接口回调点击事件
@@ -52,12 +52,21 @@ abstract class CommonAdapter<T>(var mContext: Context, var mData: ArrayList<T>,
     override fun onBindViewHolder(holder: ViewHolder, position: Int) {
         //绑定数据
         bindData(holder, mData[position], position)
+
+//        if (mItemClickListener != null) {
+//            holder.itemView.setOnClickListener { mItemClickListener!!.onItemClick(mData[position], position) }
+//        }
+//        //长按点击事件
+//        if (mItemLongClickListener != null) {
+//            holder.itemView.setOnLongClickListener { mItemLongClickListener!!.onItemLongClick(mData[position], position) }
+//        }
         //条目点击事件
-        if (mItemClickListener != null) {
+        mItemClickListener?.let {
             holder.itemView.setOnClickListener { mItemClickListener!!.onItemClick(mData[position], position) }
         }
+
         //长按点击事件
-        if (mItemLongClickListener != null) {
+        mItemLongClickListener?.let {
             holder.itemView.setOnLongClickListener { mItemLongClickListener!!.onItemLongClick(mData[position], position) }
         }
     }