我想在 view-pager 中为 3 个不同的选项卡显示 3 个不同的片段，Tabbed activity Android

Question

我是 android 的新手，这次我通过观看视频教程创建了一个带选项卡 activity 的查看寻呼机。如果用户滑动 tab1（显示第一个片段）、tab2（显示第二个片段）tab3（显示第三个片段）等位置，则问题或需求是显示 3 个不同的片段现在它显示所有选项卡的一个且唯一的片段

这是我的适配器 class，名为 datafragment 包裹 com.example.jaison.news;

public class datafragment extends Fragment {
View view;
ViewPager viewPager;
TabLayout tabLayout;


@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    view= inflater.inflate(R.layout.sample,container,false);


    viewPager = (ViewPager) view.findViewById(R.id.viewpager);
    viewPager.setAdapter(new sliderAdapter(getChildFragmentManager()));
    tabLayout = (TabLayout) view.findViewById(R.id.sliding_tabs);
    tabLayout.post(new Runnable() {
        @Override
        public void run() {
            tabLayout.setupWithViewPager(viewPager);
        }
    });

    return view;

}




private class sliderAdapter extends FragmentPagerAdapter{

    final  String tabs[]={"tab1", "tab2","tab3"};
    public sliderAdapter(FragmentManager fm) {
        super(fm);
    }


    @Override
    public Fragment getItem(int position) {
        Fragment fragment = null;

        return fragment;
    }


    @Override
    public int getCount() {


       return 3;
    }
   @Override
   public CharSequence getPageTitle(int position) {
        return tabs[position];
   }
}




 }

对于那些不明白我的意思的人，我只需要像这样实现代码，但我不确定这一点..

        switch (position) {
            case 0:

                //showing first fragment


            case 1: 

                    //showing second fragment


            case 2:
                //showing third fragment
            default:
                return new Fragment();
        }

Answer 1

像这样更改您的 getItem 方法

 @Override
public Fragment getItem(int position) {
    Fragment fragment = null;
    switch (position){
        case 0:
            fragment = new Tab1Fragment();
            break;
        case 1:
            fragment = new Tab2Fragment();
            break;
       case 2:
            fragment = new Tab3Fragment();
            break;
    }
    return fragment;
}

Answer 2

使用这个：

private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        // adding the fragments here with titles
        adapter.addFragment(new OneFragment(), "ONE");
        adapter.addFragment(new TwoFragment(), "TWO");
        adapter.addFragment(new ThreeFragment(), "THREE");
        viewPager.setAdapter(adapter);
    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }

        public void addFragment(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
            //return null;
        }
    }

然后这样设置：

ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);

tabLayout = (TabLayout) view.findViewById(R.id.sliding_tabs);
tabLayout.setupWithViewPager(viewPager);

希望对您有所帮助！！！

Answer 3

您需要创建一个 viewPagerAdapter 实例，然后向其中添加项目。像这样：

ViewPagerAdapter viewpagerAdapter = new ViewPagerAdapter(getChildFragmentManager());

viewPager.setAdapter(viewpagerAdapter);

// then add items to it as you add items to a recyclerview adapter or to any list

viewpagerAdapter.addFragment(new Fragment1(), "title1");

viewpager 适配器的自定义代码是：

public class ViewPagerAdapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    public void addFragment(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }
}

此外，由于您是编程新手，建议您使用正确的命名法，例如。类的名字总是以首字母大写开头

class ClassName 

void methodName

Answer 4

MainActivity

import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

    viewPager = (ViewPager) findViewById(R.id.viewpager);
    setupViewPager(viewPager);

    tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(viewPager);
}

private void setupViewPager(ViewPager viewPager) {
    ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
    adapter.addFragment(new OneFragment(), "ONE");
    adapter.addFragment(new TwoFragment(), "TWO");
    adapter.addFragment(new ThreeFragment(), "THREE");
    viewPager.setAdapter(adapter);
}

class ViewPagerAdapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    public void addFragment(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }
}
}

OneFragment.java

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


public class OneFragment extends Fragment{

public OneFragment() {
    // Required empty public constructor
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_one, container, false);
}

}

fragment_one.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/one"
    android:textSize="40dp"
    android:textStyle="bold"
    android:layout_centerInParent="true"/>

 </RelativeLayout>

Likewise create few more fragment activities with same code we used for OneFragment.java.

Answer 5

查看这个简单的完整示例：在这里我也使用了 TabLayout，它经常与 ViewPager 一起使用，所以接下来对你有用。

需要API:

compile 'com.android.support:design:25.3.1'

如果想在这种情况下变得更简单，您可以忽略并从 xml 和 java 文件中删除 TabLayout 的所有部分。

1. 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"
android:layout_width="match_parent"
android:layout_height="match_parent">

<android.support.v4.view.ViewPager
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/viewPager"/>

    <android.support.design.widget.TabLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorPrimary"
        app:tabIndicatorColor="@color/colorPrimaryDark"
        app:layout_scrollFlags="scroll|enterAlways"
        android:id="@+id/tabLayout"/>

</RelativeLayout>

2。片段Tab1.xml

<?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">

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:text="TAB 1"
    android:id="@+id/textTab1"/>

</RelativeLayout>

3。片段Tab2.xml

<?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">

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:text="TAB 2"
    android:id="@+id/textTab2"/>

</RelativeLayout>

4。片段Tab3.xml

<?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">

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:text="TAB 3"
    android:id="@+id/textSpacerNoTitleab3"/>

</RelativeLayout>

5. MainActivity.java

public class MainActivity extends AppCompatActivity
    implements TabLayout.OnTabSelectedListener, ViewPager.OnPageChangeListener{

ViewPager viewPager;
TabLayout tabLayout;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    viewPager = (ViewPager) findViewById(R.id.viewPager);
    tabLayout = (TabLayout) findViewById(R.id.tabLayout);

    tabLayout.addTab(tabLayout.newTab().setText("Page 1"));
    tabLayout.addTab(tabLayout.newTab().setText("Page 2"));
    tabLayout.addTab(tabLayout.newTab().setText("Page 3"));
    tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
    tabLayout.addOnTabSelectedListener(this);

    viewPager.setAdapter(new VPAdapter(getSupportFragmentManager()));
    viewPager.addOnPageChangeListener(this);
}

@Override
public void onTabSelected(TabLayout.Tab tab) {
    w("onTabSelected(): "+tab.getPosition());
    viewPager.setCurrentItem(tab.getPosition());
}

@Override
public void onTabUnselected(TabLayout.Tab tab) {

}

@Override
public void onTabReselected(TabLayout.Tab tab) {

}

@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

}

@Override
public void onPageSelected(int position) {
    w("onPageSelected(): "+position);
    TabLayout.Tab tab = tabLayout.getTabAt(position);
    if(tab!=null)tab.select();
}

@Override
public void onPageScrollStateChanged(int state) {

}

void w(String string){
    Log.w("MKN",getClass().getSimpleName()+" "+string);
}
}

6.片段classTab1.java public class Tab1 扩展片段 {

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    super.onCreateView(inflater, container, savedInstanceState);
    return inflater.inflate(R.layout.tab1,container,false);
}
}

7.片段classTab2.java

public class Tab2 extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    super.onCreateView(inflater, container, savedInstanceState);
    return inflater.inflate(R.layout.tab2,container,false);
}
}

8.片段classTab3.java

public class Tab3 extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    super.onCreateView(inflater, container, savedInstanceState);
    return inflater.inflate(R.layout.tab3,container,false);
}
}

9.适配器 class VPAdapter.java

public class VPAdapter extends FragmentPagerAdapter {

public VPAdapter(FragmentManager fm) {
    super(fm);
}

@Override
public Fragment getItem(int position) {
    if(position == 0) return new Tab1();
    if(position == 1) return new Tab2();
    if(position == 2) return new Tab3();

    throw new IllegalStateException("Unexpected position " + position);
}

@Override
public int getCount() {
    return 3;
}
}

我想在 view-pager 中为 3 个不同的选项卡显示 3 个不同的片段，Tabbed activity Android

I want to show 3 different fragments for 3 different tabs in view-pager ,Tabbed activity Android

java

android

android-fragments

android-viewpager

android-tabbed-activity