android基础控件（2）TabLayout+ViewPager实现选项卡

2.1 activity_main

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"xmlns:app="http://schemas.android.com/apk/res-auto"android:orientation="vertical"android:background="#cfcfcf"><com.google.android.material.tabs.TabLayoutandroid:layout_width="match_parent"android:layout_height="30dp"android:id="@+id/tab1"app:tabMode="scrollable"android:background="@color/colorPrimaryDark"/><androidx.viewpager.widget.ViewPagerandroid:layout_width="match_parent"android:layout_height="match_parent"android:id="@+id/vp1"/>
</LinearLayout>

2.2 Main_Activity

public class MainActivity extends AppCompatActivity {private TabLayout tabLayout;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);viewPager=findViewById(R.id.vp1);tabLayout=findViewById(R.id.tab1);initViewpage();}private void initViewpage() {List<String> title=new ArrayList<>();title.add("精选");title.add("体育");title.add("巴萨");title.add("购物");title.add("明星");title.add("视频");title.add("健康");title.add("励志");title.add("图文");title.add("本地");title.add("动漫");title.add("搞笑");title.add("科技");for (int i=0;i<title.size();i++){tabLayout.addTab(tabLayout.newTab().setText(title.get(i)));}List<Fragment> fragments=new ArrayList<>();for (int i=0;i<title.size();i++){fragments.add(new ListFragment());}FragmentAdapter fragmentAdapter=new FragmentAdapter(getSupportFragmentManager(),fragments,title);viewPager.setAdapter(fragmentAdapter);tabLayout.setupWithViewPager(viewPager);tabLayout.setTabsFromPagerAdapter(fragmentAdapter);}
}

2.3 FragmentAdapter类

public class FragmentAdapter extends FragmentStatePagerAdapter {private  List<Fragment> mfragmentList;private List<String> mtitles;public  FragmentAdapter(FragmentManager fm, List<Fragment> fragmentList,List<String> titles){super(fm);this.mfragmentList=fragmentList;this.mtitles=titles;}@NonNull@Overridepublic Fragment getItem(int position) {return mfragmentList.get(position);}@Overridepublic int getCount() {return mfragmentList.size();}@Nullable@Overridepublic CharSequence getPageTitle(int position) {return mtitles.get(position);}
}

2.4 ListFragment类

public class ListFragment extends Fragment {
// private RecyclerView recyclerView;private ListView listView;private ArrayAdapter<String> arrayAdapter;private String[] data={"Apple","Banana","Orange","Watermelon","Pear","Grape","Pineapple","Strawberry","Cherry","Mango","Apple","Banana","Orange","Watermelon","Pear","Grape","Pineapple","Strawberry","Cherry","Mango"};@Nullable@Overridepublic View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
//View view=inflater.inflate(R.layout.list_fragment,container,false);listView=view.findViewById(R.id.list11);arrayAdapter=new ArrayAdapter<String>(getContext(),android.R.layout.simple_list_item_1,data);listView.setAdapter(arrayAdapter);return view;}@Overridepublic void onActivityCreated(@Nullable Bundle savedInstanceState) {super.onActivityCreated(savedInstanceState);}
}

2.5 list_fragment布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:orientation="vertical" android:layout_width="match_parent"android:layout_height="match_parent"><ListViewandroid:id="@+id/list11"android:layout_width="match_parent"android:layout_height="match_parent"/>
</LinearLayout>

上面的实例采用最简单的方式生成多个相同的Fragment,在实际的开发过程中，每个选项卡的tab不可能是一样的，所以一般Fragement的Adapter不选用以上的FragmentStatePagerAdapter作为父类，而是采用FragmentPagerAdapter，这个将在后面的项目实例中详细讲解。另外TabLayout和ViewPager属于Material Design组件，需要添加相关依赖：配置design support library的API

使用androidX的配置：

dependencies {implementation fileTree(include: ['*.jar'], dir: 'libs')implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"implementation 'androidx.appcompat:appcompat:1.0.0-alpha3'implementation 'androidx.constraintlayout:constraintlayout:1.1.1'testImplementation 'junit:junit:4.12'androidTestImplementation 'androidx.test:runner:1.1.0-alpha3'androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0-alpha3'implementation 'com.google.android.material:material:1.0.0-alpha3'implementation 'androidx.cardview:cardview:1.0.0-alpha3'
}

使用过去的android的配置：

dependencies {implementation fileTree(include: ['*.jar'], dir: 'libs')implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"implementation 'com.android.support:appcompat-v7:28.0.0-alpha3'implementation 'com.android.support.constraint:constraint-layout:1.1.1'testImplementation 'junit:junit:4.12'androidTestImplementation 'com.android.support.test:runner:1.0.2'androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'implementation 'com.android.support:design:28.0.0-alpha3'implementation 'com.android.support:cardview-v7:28.0.0-alpha3'
}