这是我的解决方案(Android Studio 3.6):
在 app/build.gradle 中:
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation('com.crashlytics.sdk.android:crashlytics:2.10.1@aar') { transitive = true; }
implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
implementation 'com.google.android.material:material:1.1.0-beta01'
implementation 'org.altbeacon:android-beacon-library:2.16.3'
implementation 'androidx.localbroadcastmanager:localbroadcastmanager:1.0.0'
implementation 'androidx.viewpager2:viewpager2:1.0.0-beta05'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test.ext:junit:1.1.1'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
implementation "androidx.core:core-ktx:+"
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
}
这是我的活动:
import android.os.Bundle;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.viewpager2.widget.ViewPager2;
import java.util.ArrayList;
import java.util.List;
import com.myproject.android.R;
import com.myproject.android.adapter.CustomFragmentStateAdapter;
import com.myproject.android.ui.fragment.BluetoothPageFragment;
import com.myproject.android.ui.fragment.QrPageFragment;
public class QRBluetoothSwipeActivity extends AppCompatActivity {
private ViewPager2 myViewPager2;
private CustomFragmentStateAdapter myAdapter;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
// Make sure this is before calling super.onCreate
setTheme(R.style.AppTheme); // show splash screen
super.onCreate(savedInstanceState);
setContentView(R.layout.qr_bluetooth_swipe_activity);
init();
}
private void init() {
List<Fragment> fragmentList = new ArrayList<Fragment>();
QrPageFragment m1 = new QrPageFragment();
BluetoothPageFragment m2 = new BluetoothPageFragment();
myViewPager2 = findViewById(R.id.viewPager2);
fragmentList.add(m2);
fragmentList.add(m1);
myAdapter = new CustomFragmentStateAdapter(this, fragmentList);
myViewPager2.setAdapter(myAdapter);
}
}
这里是布局:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.actviity.SplashDelayActivity">
<androidx.viewpager2.widget.ViewPager2
android:id="@+id/viewPager2"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
这里是我的CustomFragmentStateAdapter
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentActivity;
import androidx.viewpager2.adapter.FragmentStateAdapter;
import org.jetbrains.annotations.NotNull;
import java.util.ArrayList;
import java.util.List;
public class CustomFragmentStateAdapter extends FragmentStateAdapter {
private List<Fragment> listFragment = new ArrayList<>();
public CustomFragmentStateAdapter(FragmentActivity fa, List<Fragment> list) {
super(fa);
listFragment = list;
}
@NotNull
@Override
public Fragment createFragment(int position) {
return listFragment.get(position);
}
@Override
public int getItemCount() {
return 2;
}
}
这是我的代码片段:
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import com.myproject.android.R;
public class BluetoothPageFragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.bluetooth_page_fragment, container, false);
}
}
和第二个片段:
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import com.myproject.android.R;
public class QrPageFragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.qr_page_fragment, container, false);
}
}
现在我使用androidx.viewpager2.widget.ViewPager2
与我的自定义片段。
它可以工作!!!
很好。
P.S. 另一个实现:
public class CustomFragmentStateAdapter extends FragmentStateAdapter {
private ArrayList<Fragment> arrayList = new ArrayList<>();
public CustomFragmentStateAdapter (FragmentActivity fa) {
super(fa);
}
public void addFragment(Fragment fragment) {
arrayList.add(fragment);
}
@Override
public int getItemCount() {
return arrayList.size();
}
@NonNull
@Override
public Fragment createFragment(int position) {
// return your fragment that corresponds to this 'position'
return arrayList.get(position);
}
}
然后在活动中这样使用:
myViewPager2 = findViewById(R.id.viewPager2);
myAdapter = new CustomFragmentStateAdapter (this);
myAdapter.addFragment(new QrPageFragment());
myAdapter.addFragment(new BluetoothPageFragment());
myViewPager2.setAdapter(myAdapter);
FragmentStateAdapter
的 createFragment
回调函数应该(正如它的名称所示)创建一个 Fragment
,而不是返回已经创建好并且正在等待中的 Fragment
。使用你的方法会干扰 FragmentManager
的操作。 - Bartek LipinskicreateFragment
中按位置返回了一个项目。一切都按预期工作,无需每次重新创建片段。但是适配器是这样调用的:val adapter = object : FragmentStateAdapter(childFragmentManager, viewLifecycleOwner.lifecycle)
。 - CoolMindFragmentManager
是相当复杂的机制(约 4k 行代码),如果不遵循其 API,你可能会遇到一些边缘情况和不确定的行为。 - Bartek Lipinskiclass SurveyPagerAdapter(
private val fragmentList: MutableList< Fragment>,
fragment: FragmentManager,
lifecycle: Lifecycle) : FragmentStateAdapter(fragment,lifecycle){
override fun getItemCount(): Int = fragmentList.size
override fun createFragment(position: Int): Fragment {
return fragmentList[position]
}
fun getFragmentName(position: Int) = fragmentList[position]
fun addFragment(fragment: Fragment) {
fragmentList.add(fragment)
notifyDataSetChanged()
}}
Kotlin Activity *只需在onCreate()方法中添加一个方法*
private fun setUpViewPager(){
val fragmentList : MutableList< Fragment> = mutableListOf()
fragmentList.add(SurveyPageOneFragment.newInstance(true))
fragmentList.add(SurveyPageTwoFragment.newInstance(true))
fragmentList.add(SurveyPageThreeFragment.newInstance(true))
fragmentList.add(SurveyPageFourFragment.newInstance(true))
fragmentList.add(SurveyPageFiveFragment.newInstance(true))
surveyPagerAdapter = SurveyPagerAdapter(fragmentList,supportFragmentManager,lifecycle)
binding.viewPager.adapter = surveyPagerAdapter
binding.dotsIndicator.attachTo(binding.viewPager)
}
Kotlin碎片
class SurveyPageOneFragment : Fragment() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
arguments?.let {
}
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_survey_page_one, container, false)
}
companion object {
@JvmStatic
fun newInstance(isMyBoolean: Boolean) = SurveyPageOneFragment().apply {
val fragment = SurveyPageOneFragment()
arguments = Bundle().apply {
putBoolean("REPLACE WITH A STRING CONSTANT", isMyBoolean)
}
fragment.arguments
return fragment
}
}}
在ViewPager2中的XML代码
<androidx.viewpager2.widget.ViewPager2
android:id="@+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layoutDirection="ltr"/>
圆点指示器
库//Kotlin圆点指示器实现'com.tbuonomo:dotsindicator:4.3'
<com.tbuonomo.viewpagerdotsindicator.DotsIndicator
android:id="@+id/dots_indicator"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:dotsColor="@color/colorSurveyEditGreenLight"
app:dotsCornerRadius="8dp"
app:dotsSize="16dp"
app:dotsSpacing="4dp"
app:dotsWidthFactor="2.5"
app:selectedDotColor="@color/white"
app:progressMode="true"
/>
我个人在 Fragment 中使用了 ViewPager2。这是我的做法。GitHub 上有示例代码 [https://github.com/codebyjames/Example-Using-ViewPager2-Slide-Page-Adapter]
首先,在 onCreate 方法中:
// pager adapter
val pagerAdapter = ScreenSlidePageAdapter(this@ManagerFragment)
viewPager.adapter = pagerAdapter
viewPager.setPageTransformer(ZoomOutPageTransformer())
ViewPager的适配器
class ScreenSlidePageAdapter(val fragment: Fragment): FragmentStateAdapter(fragment) {
val fragments = listOf(WalkThroughFragment(), PermissionsFragment(), DatastoreFragment())
override fun getItemCount(): Int {
return fragments.size
}
override fun createFragment(position: Int): Fragment {
return fragments[position]
}
}
ViewPager2 的转换 - 可选
class ZoomOutPageTransformer : ViewPager2.PageTransformer {
override fun transformPage(view: View, position: Float) {
view.apply {
val pageWidth = width
val pageHeight = height
when {
position < -1 -> { // [-Infinity,-1)
// This page is way off-screen to the left.
alpha = 0f
}
position <= 1 -> { // [-1,1]
// Modify the default slide transition to shrink the page as well
val scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position))
val vertMargin = pageHeight * (1 - scaleFactor) / 2
val horzMargin = pageWidth * (1 - scaleFactor) / 2
translationX = if (position < 0) {
horzMargin - vertMargin / 2
} else {
horzMargin + vertMargin / 2
}
// Scale the page down (between MIN_SCALE and 1)
scaleX = scaleFactor
scaleY = scaleFactor
// Fade the page relative to its size.
alpha = (MIN_ALPHA +
(((scaleFactor - MIN_SCALE) / (1 - MIN_SCALE)) * (1 - MIN_ALPHA)))
}
else -> { // (1,+Infinity]
// This page is way off-screen to the right.
alpha = 0f
}
}
}
}
}
我的 ManagerFragment 布局(包含 ViewPager2)
<androidx.viewpager2.widget.ViewPager2
android:id="@+id/viewPager"
android:layout_width="match_parent"
android:layout_height="match_parent" />