Question

首先，我是Android编程的初学者。我要做的是编写三个Tabs，每个ListView里面都有一个ListView（你知道它来自例如WhatsApp）。 Android Studio可以轻松自动创建选项卡式活动。所以问题是：如何为每个Tab实现ListView？实际上有一个很好的教程http://www.androidhive.info/2012/05/android-combining-tab-layout-and-list-view/使用TabActivity。但是，不推荐使用此方法，而应使用Fragments。我使用ListView扩展了main_fragment.xml（由Android Studio创建）。但是，设置相应列表适配器的正确方法是什么，尤其是设置它们的位置？由于空对象引用错误，将它们设置为ListView list_all = (ListView) findViewById(R.id.listViewAll)中的onCreate()不起作用。另外，我没有找到如何使用rootView返回的onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState)所以我该如何解决这个问题呢？

main_fragment.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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:background="@color/colorAccent"
    android:paddingTop="@dimen/activity_vertical_margin">

    <ListView
        android:id="@+id/listViewAll"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></ListView>

</RelativeLayout>

main.xml中：

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.CoordinatorLayout 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:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    android:background="@color/white"

    tools:context="de.url.members">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="@dimen/appbar_padding_top"
        android:background="@color/bg_login_dark"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="@color/bg_login_dark"
            app:layout_scrollFlags="scroll|enterAlways"
            app:popupTheme="@style/AppTheme.PopupOverlay">

        </android.support.v7.widget.Toolbar>

        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabMaxWidth="0dp"
            app:tabGravity="fill"
            app:tabMode="fixed"
            android:fillViewport="false" />

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end|bottom"
        android:layout_margin="@dimen/fab_margin"
        android:src="@android:drawable/ic_dialog_email" />

</android.support.design.widget.CoordinatorLayout>

main.java：

public class main extends AppCompatActivity {

    /**
     * The {@link android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. We use a
     * {@link FragmentPagerAdapter} derivative, which will keep every
     * loaded fragment in memory. If this becomes too memory intensive, it
     * may be best to switch to a
     * {@link android.support.v4.app.FragmentStatePagerAdapter}.
     */
    private SectionsPagerAdapter mSectionsPagerAdapter;


    // The {@link ViewPager} that will host the section contents.
    private ViewPager mViewPager;


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


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

        // Create the adapter that will return a fragment for each of the three
        // primary sections of the activity.
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);

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

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
            // action here
            }
        });
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_members, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.logout) {
            //action here
        }

        return super.onOptionsItemSelected(item);
    }


    /**
     * A placeholder fragment containing a simple view.
     */

    public static class PlaceholderFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        private static final String ARG_SECTION_NUMBER = "section_number";

        public PlaceholderFragment() {
        }

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {

            int sectionNumber = getArguments().getInt(ARG_SECTION_NUMBER);//INDEX of selected TAB
            View rootView;

            if (sectionNumber == 1){
                rootView = inflater.inflate(R.layout.main_fragment, container, false);
            }else if (sectionNumber == 2){
                rootView = inflater.inflate(R.layout.main_fragment, container, false);                 
            }else if (sectionNumber == 3){
                rootView = inflater.inflate(R.layout.main_fragment, container, false);                  
            }else{
                rootView = inflater.inflate(R.layout.main_fragment, container, false);

            }

            return rootView;
        }
    }

    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

        @Override
        public Fragment getItem(int position) {
            // getItem is called to instantiate the fragment for the given page.
            // Return a PlaceholderFragment (defined as a static inner class below).
            return PlaceholderFragment.newInstance(position + 1);
        }

        @Override
        public int getCount() {
            // Show 3 total pages.
            return 3;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
                case 0:
                    return getResources().getString(R.string.title_section1);
                case 1:
                    return getResources().getString(R.string.title_section2);
                case 2:
                    return getResources().getString(R.string.title_section3);
            }
            return null;
        }
    }
}

Answer 1

如果你想使用list with tablayout和viewpager尝试这种方式它将适合你

public class MainActivity extends AppCompatActivity {
    private static Toolbar toolbar;
    private static ViewPager viewPager;
    private static TabLayout tabLayout;

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

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

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

        tabLayout = (TabLayout) findViewById(R.id.tabLayout);
        tabLayout.setupWithViewPager(viewPager);//setting tab over viewpager

        //Implementing tab selected listener over tablayout
        tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());//setting current selected item over viewpager
                switch (tab.getPosition()) {
                    case 0:
                        Log.e("TAG","TAB1");
                        break;
                    case 1:
                        Log.e("TAG","TAB2");
                        break;
                    case 2:
                        Log.e("TAG","TAB3");
                        break;
                }
            }

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

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


    //Setting View Pager
    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFrag(new DummyFragment("ANDROID"), "ANDROID");
        adapter.addFrag(new DummyFragment("iOS"), "iOS");
        adapter.addFrag(new DummyFragment("WINDOWS"), "WINDOWS");
        viewPager.setAdapter(adapter);
    }


    //View Pager fragments setting adapter class
    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();//fragment arraylist
        private final List<String> mFragmentTitleList = new ArrayList<>();//title arraylist

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

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

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


        //adding fragments and title method
        public void addFrag(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

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

有关详情，请参阅android-material-design-tabs-using-tablayout

OR

选中此http://www.tutorialsbuzz.com/2015/10/Android-Sliding-TabLayout-ListView-WhatsApp.html

并查看此https://github.com/codepath/android_guides/wiki/Handling-Scrolls-with-CoordinatorLayout

<强>输出

Answer 2

我将解释如何将ListView放在其中一个片段上。（对不起，如果我写错了英文）

你应该把你的listView视图放在xml上，由你的一个片段显示。在您发布的代码中，布局巫婆片段显示为R.layout.main_fragment

然后在片段上你必须声明你的ListView：

ListView list_all = (ListView) rootView.findViewById(R.id.listViewAll);

你必须创建一个ListView适配器，一个对象类和一些其他文件，你可以使用你发布的教程。

Link

然后编写代码，在片段上分配rootView后将适配器设置为此ListView：

if (sectionNumber == 1){
        rootView = inflater.inflate(R.layout.main_fragment, container, false);
        }else if (sectionNumber == 2){
            rootView = inflater.inflate(R.layout.main_fragment, container, false);                 
        }else if (sectionNumber == 3){
            rootView = inflater.inflate(R.layout.main_fragment, container, false);                  
        }else{
            rootView = inflater.inflate(R.layout.main_fragment, container, false);
}

ArrayList<Object> arrayListOfObjects = new ArrayList<>();
arrayListOfObjects.add(new Object(...));
MyAdapter adapter = new MyAdapter(arrayListOfObjects);
list_all.setListAdapter(adapter);

Answer 3

我现在只需编辑main.java中的getItem() public class SectionsPagerAdapter方法就解决了这个问题。只需返回默认的ListFragment而不是PlaceholderFragment。有趣的说明：为所有选项卡返回相同的ListFragment对象会导致错误。

main.java：

public class MainActivity extends AppCompatActivity {

    private ArrayAdapter<String> adapter;

    private ListFragment contacts1 = new ListFragment();
    private ListFragment contacts2 = new ListFragment();
    private ListFragment contacts3 = new ListFragment();

    List<String> words = new ArrayList<String>();

    private SectionsPagerAdapter mSectionsPagerAdapter;

    /**
     * The {@link ViewPager} that will host the section contents.
     */
    private ViewPager mViewPager;

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

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        // Create the adapter that will return a fragment for each of the three
        // primary sections of the activity.
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);

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

        words.add("Hello");
        words.add("World");
        words.add("!");
        adapter = new ArrayAdapter<String>(this,R.layout.item,words);
        contacts1.setListAdapter(adapter);
        contacts2.setListAdapter(adapter);
        contacts3.setListAdapter(adapter);


        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Update List", Snackbar.LENGTH_LONG).setAction("Action", null).show();
                words.add("New Item");
                adapter.notifyDataSetInvalidated();
            }
        });

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }


    public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

        @Override
        public ListFragment getItem(int position) {

            if (position == 0){
                return contacts1;
            }else if (position == 1){
                return contacts2;
            }else{
                return contacts3;
            }


        }

        @Override
        public int getCount() {
            // Show 3 total pages.
            return 3;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
                case 0:
                    return "SECTION 1";
                case 1:
                    return "SECTION 2";
                case 2:
                    return "SECTION 3";
            }
            return null;
        }
    }
}

如何使用ListViews创建选项卡式活动 - Android

3 个答案: