Viewpager2+Fragment+指示器

• 效果展示：

1. MainActivity.java

package com.huawei.myviewpager;import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.viewpager2.widget.ViewPager2;import android.os.Bundle;
import android.view.View;
import android.widget.LinearLayout;import com.huawei.myviewpager.adapter.MyFragmentPagerAdapter;
import com.huawei.myviewpager.fragment.FirstFragment;
import com.huawei.myviewpager.fragment.SecondFragment;
import com.huawei.myviewpager.fragment.ThirdFragment;import java.util.ArrayList;
import java.util.List;public class MainActivity extends AppCompatActivity {private MyFragmentPagerAdapter mAdapter;private ViewPager2 mViewpager;private List<Fragment> mList;private LinearLayout mPointIndicator;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mList = new ArrayList<>();mList.add(new FirstFragment());mList.add(new SecondFragment());mList.add(new ThirdFragment());mAdapter = new MyFragmentPagerAdapter(this, mList);initView();}private void initView() {mViewpager = findViewById(R.id.vp2);mViewpager.setAdapter(mAdapter);mPointIndicator = findViewById(R.id.fragment_indicator);insertPoint();mViewpager.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {@Overridepublic void onPageSelected(int position) {int realPosition;if (position != 0) {realPosition = position % 3;} else {realPosition = 0;}setSelectPoint(realPosition);}});}private void insertPoint() {for (int i = 0; i < 3; i++) {View point = new View(MainActivity.this);LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(40, 40);layoutParams.topMargin = 20;if (i == 0) {point.setBackground(getResources().getDrawable(R.drawable.indicator_point_selected));} else {point.setBackground(getResources().getDrawable(R.drawable.indicator_point_unselected));}point.setLayoutParams(layoutParams);mPointIndicator.addView(point);}}private void setSelectPoint(int realPosition) {for (int i = 0; i < mPointIndicator.getChildCount(); i++) {View point = mPointIndicator.getChildAt(i);if (i == realPosition) {point.setBackgroundResource(R.drawable.indicator_point_selected);} else {point.setBackgroundResource(R.drawable.indicator_point_unselected);}}}
}

2. activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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=".MainActivity"><androidx.viewpager2.widget.ViewPager2android:id="@+id/vp2"android:orientation="vertical"android:layout_width="match_parent"android:layout_height="match_parent" /><LinearLayoutandroid:id="@+id/fragment_indicator"android:layout_width="40dp"android:layout_height="100dp"android:layout_alignParentEnd="true"android:layout_marginEnd="32dp"android:layout_marginTop="80dp"android:gravity="center"android:orientation="vertical" /></RelativeLayout>

3. MyFragmentPagerAdapter

package com.huawei.myviewpager.adapter;import java.util.List;import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentActivity;
import androidx.viewpager2.adapter.FragmentStateAdapter;public class MyFragmentPagerAdapter extends FragmentStateAdapter {private List<Fragment> mList;public MyFragmentPagerAdapter(@NonNull FragmentActivity fragmentActivity, List<Fragment> list) {super(fragmentActivity);mList = list;}@NonNull@Overridepublic Fragment createFragment(int position) {Fragment fragment = mList.get(position);return fragment;}@Overridepublic int getItemCount() {return mList.size();}
}

4. FirstFragment.java

public class FirstFragment extends Fragment {@Nullable@Overridepublic View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {return inflater.inflate(R.layout.fragment_first, container, false);}
}

5. fragment_first.xml，三个fragment相同布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"><ImageViewandroid:layout_width="match_parent"android:layout_height="match_parent"android:scaleType="fitXY"android:src="@drawable/img9" />
</RelativeLayout>

6. indicator_point_selected.xml 指示器选中shape

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"><corners android:radius="250dp" /><solid android:color="#FF000000" /><stroke android:color="#FF000000" />
</shape>

7. indicator_point_unselected.xml 指示器未选中shape

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"><corners android:radius="250dp" /><solid android:color="#FFFFFFFF" /><strokeandroid:width="1dp"android:color="#FF000000" />
</shape
://schemas.android.com/apk/res/android"><corners android:radius="250dp" /><solid android:color="#FFFFFFFF" /><strokeandroid:width="1dp"android:color="#FF000000" />
</shape