Optimize sample.

app/src/main/java/com/example/zhpan/circleviewpager/activity/MainActivity.kt

@@ -25,16 +25,16 @@ class MainActivity : AppCompatActivity() {
 
     private fun initData() {
         val mAdapter = AdapterFragmentPager(supportFragmentManager)
-        vp_fragment!!.adapter = mAdapter
-        vp_fragment!!.disableTouchScroll(true)
-        vp_fragment!!.offscreenPageLimit = 2
-        vp_fragment!!.addOnPageChangeListener(object : ViewPager.OnPageChangeListener {
+        vp_fragment?.adapter = mAdapter
+        vp_fragment?.disableTouchScroll(true)
+        vp_fragment?.offscreenPageLimit = 2
+        vp_fragment?.addOnPageChangeListener(object : ViewPager.OnPageChangeListener {
             override fun onPageScrolled(position: Int, positionOffset: Float, positionOffsetPixels: Int) {
 
             }
 
             override fun onPageSelected(position: Int) {
-                rg_tab!!.check(getCheckedId(position))
+                rg_tab?.check(getCheckedId(position))
             }
 
             override fun onPageScrollStateChanged(state: Int) {
@@ -54,15 +54,15 @@ class MainActivity : AppCompatActivity() {
     }
 
     private fun setListener() {
-        rg_tab!!.setOnCheckedChangeListener { group, checkedId ->
+        rg_tab?.setOnCheckedChangeListener { group, checkedId ->
             if (checkedId == R.id.rb_home) {
-                vp_fragment!!.setCurrentItem(AdapterFragmentPager.PAGE_HOME, false)
+                vp_fragment?.setCurrentItem(AdapterFragmentPager.PAGE_HOME, false)
 
             } else if (checkedId == R.id.rb_find) {
-                vp_fragment!!.setCurrentItem(AdapterFragmentPager.PAGE_FIND, false)
+                vp_fragment?.setCurrentItem(AdapterFragmentPager.PAGE_FIND, false)
 
             } else if (checkedId == R.id.rb_add) {
-                vp_fragment!!.setCurrentItem(AdapterFragmentPager.PAGE_OTHERS, false)
+                vp_fragment?.setCurrentItem(AdapterFragmentPager.PAGE_OTHERS, false)
             }
         }
     }

app/src/main/java/com/example/zhpan/circleviewpager/activity/WelcomeActivity.kt

@@ -79,7 +79,7 @@ class WelcomeActivity : BaseDataActivity(), HolderCreator<CustomPageViewHolder>
     }
 
     private fun updateUI(position: Int) {
-        tv_describe!!.text = des[position]
+        tv_describe?.text = des[position]
         val translationAnim = ObjectAnimator.ofFloat(tv_describe, "translationX", -120f, 0f)
         translationAnim.duration = ANIMATION_DURATION.toLong()
         translationAnim.interpolator = DecelerateInterpolator()
@@ -89,13 +89,13 @@ class WelcomeActivity : BaseDataActivity(), HolderCreator<CustomPageViewHolder>
         animatorSet.playTogether(translationAnim, alphaAnimator1)
         animatorSet.start()
 
-        if (position == mViewPager.list.size - 1 && btn_start!!.visibility == View.GONE) {
-            btn_start!!.visibility = View.VISIBLE
+        if (position == mViewPager.list.size - 1 && btn_start?.visibility == View.GONE) {
+            btn_start?.visibility = View.VISIBLE
             ObjectAnimator
                     .ofFloat(btn_start, "alpha", 0f, 1f)
                     .setDuration(ANIMATION_DURATION.toLong()).start()
         } else {
-            btn_start!!.visibility = View.GONE
+            btn_start?.visibility = View.GONE
         }
     }