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TabHost with Fragments and FragmentActivity

由 ℡╲_俬逩灬. 提交于 2019-11-26 04:39:55

问题


I\'m working on an Android App and I want to use 3 tabs for navigation using Fragments for each tab, but I don\'t know how to create the structure for doing it.

I want to add each fragment separately because each one is different, but I don\'t know where to add them in FragmentActivity.

I have these files.

tabs_layout.xml

<LinearLayout xmlns:android=\"http://schemas.android.com/apk/res/android\"
    android:orientation=\"vertical\"
    android:layout_height=\"match_parent\"
    android:layout_width=\"match_parent\">

    <TabHost android:id=\"@android:id/tabhost\"
         android:layout_width=\"match_parent\"
         android:layout_height=\"match_parent\">

         <LinearLayout
                android:orientation=\"vertical\"
                android:layout_width=\"match_parent\"
                android:layout_height=\"match_parent\" >

             <TabWidget
                android:id=\"@android:id/tabs\" 
                android:layout_width=\"match_parent\"
                android:layout_height=\"wrap_content\"
             />

             <FrameLayout
                 android:id=\"@android:id/tabcontent\" 
                 android:layout_width=\"match_parent\"
                 android:layout_height=\"match_parent\"

             >

                 <FrameLayout
                     android:id=\"@+id/tabRateAPet\" 
                     android:layout_width=\"match_parent\"
                     android:layout_height=\"match_parent\"

                 />

                 <FrameLayout
                     android:id=\"@+id/tabViewMyRates\" 
                     android:layout_width=\"match_parent\"
                     android:layout_height=\"match_parent\"

                 />

                 <FrameLayout
                     android:id=\"@+id/tabViewGlobalRates\" 
                     android:layout_width=\"match_parent\"
                     android:layout_height=\"match_parent\"

                 />


             </FrameLayout>
        </LinearLayout>
    </TabHost>
</LinearLayout>

TabsMain.java

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;

public class MainTabsActivity extends FragmentActivity {
public static final String RATE_A_PET = \"Rate a Pet\";
public static final String MY_RATES = \"My Rates\";
public static final String GLOBAL_RATES = \"Global Rates\";

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.tabs_layout);
 }
}

Tabs.java

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TabHost;
import android.widget.TabHost.OnTabChangeListener;
import android.widget.TabHost.TabSpec;
import android.widget.TextView;

public class Tabs extends Fragment implements OnTabChangeListener {
    private static final String TAG = \"FragmentTabs\";
    public static final String RATE_A_PET = \"Rate a Pet\";
    public static final String MY_RATES = \"My Rates\";
    public static final String GLOBAL_RATES = \"Global Rates\";

    private View mRoot;
    private TabHost mTabHost;
    private int mCurrentTab;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
//      super.onCreateView(inflater, container, savedInstanceState);
        mRoot = inflater.inflate(R.layout.tabs_layout, null);
        mTabHost = (TabHost) mRoot.findViewById(android.R.id.tabhost);
        setupTabs();
        return mRoot;
    }

    private void setupTabs() {
        mTabHost.setup(); // important!
        mTabHost.addTab(newTab(RATE_A_PET, R.string.tabRateAPet, R.id.tabRateAPet));
        mTabHost.addTab(newTab(MY_RATES, R.string.tabViewMyRates, R.id.tabViewMyRates));
    }

    private TabSpec newTab(String tag, int labelId, int tabContentId) {
        Log.d(TAG, \"buildTab(): tag=\" + tag);

        View indicator = LayoutInflater.from(getActivity()).inflate(
                R.layout.tab,
                (ViewGroup) mRoot.findViewById(android.R.id.tabs), false);
        ((TextView) indicator.findViewById(R.id.text)).setText(labelId);

        TabSpec tabSpec = mTabHost.newTabSpec(tag);
        tabSpec.setIndicator(indicator);
        tabSpec.setContent(tabContentId);
        return tabSpec;
    }


    @Override
    public void onTabChanged(String tabId) {
        Log.d(TAG, \"onTabChanged(): tabId=\" + tabId);
        if (RATE_A_PET.equals(tabId)) {
            updateTab(tabId, R.id.tabRateAPet);
            mCurrentTab = 0;
            return;
        }
        if (MY_RATES.equals(tabId)) {
            updateTab(tabId, R.id.tabViewMyRates);
            mCurrentTab = 1;
            return;
        }
        if (GLOBAL_RATES.equals(tabId)) {
            updateTab(tabId, R.id.tabViewGlobalRates);
            mCurrentTab = 2;
            return;
        }
    }   
    private void updateTab(String tabId, int placeholder) {
        FragmentManager fm = getFragmentManager();
        if (fm.findFragmentByTag(tabId) == null) {
            fm.beginTransaction()
                    .replace(placeholder, new RateMyPetActivity(), tabId)
                    .commit();
        }
    }

}

回答1:


I would suggest creating a separate fragment file for each tab. I recently did this as well, so I have outlined my code below:

Layout Files

activity_main.xml 

<android.support.v4.app.FragmentTabHost
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/tabhost"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TabWidget
        android:id="@android:id/tabs"

        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0"/>

    <FrameLayout
        android:id="@android:id/tabcontent"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_weight="0"/>

    <FrameLayout
        android:id="@+id/realtabcontent"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/>

</LinearLayout>
</android.support.v4.app.FragmentTabHost>

tab1_view.xml //add your respective tab layouts using this format (make sure to change string variables)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
        tools:context=".DeviceFragment" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/tab1_fragment_string" />

</LinearLayout>

SRC Files

MainActivity.java //notice that in the .addTab process I only used text. You can also add icons using drawables that you would need to add to your hdpi folder. I also only created three tabs in this example.

package com.example.applicationname;

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTabHost;

public class MainActivity extends FragmentActivity {
    // Fragment TabHost as mTabHost
    private FragmentTabHost mTabHost;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mTabHost = (FragmentTabHost)findViewById(android.R.id.tabhost);
        mTabHost.setup(this, getSupportFragmentManager(), R.id.realtabcontent);

        mTabHost.addTab(mTabHost.newTabSpec("tab1").setIndicator("Tab1"),
            Tab1Fragment.class, null);
        mTabHost.addTab(mTabHost.newTabSpec("tab2").setIndicator("Tab2"),
            Tab2Fragment.class, null);
        mTabHost.addTab(mTabHost.newTabSpec("tab3").setIndicator("Tab3"),
            Tab3Fragment.class, null);
    }
}

Tab1Fragment.java //once again replicate for desired number of tabs

package com.example.applicationname;

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

public class Tab1Fragment extends Fragment  {

 @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View V = inflater.inflate(R.layout.tab1_view, container, false);

        return V;
    }
}

Make sure that your R.java and strings.xml files are properly set up, and then your tabs should be up and running.




回答2:


TabHost doesn't retains Fragment's states. So why using TabHost?

So use ViewPager with TabLayout instead.

Prons of Viewpager over Tabhost:

  • ViewPager retains Fragments states. Mean Fragment will not again recreated if switched.
  • Inbuilt swiping feature that gives user smoother experience.
  • Less CPU consumption, because Tabhost recreates Fragment/Activity again and again when Tab is switched.

See the difference :

Using Tablayout + ViewPager (Supports swipe, retains Fragments states

Using TabHost (Doesn't support swipe, doesn't retain states)

Small Code for Tablayout + ViewPager

// find views by id
ViewPager viewPager = findViewById(R.id.viewpager);
TabLayout tabLayout = findViewById(R.id.tablayout);

// attach tablayout with viewpager
tabLayout.setupWithViewPager(viewPager);

ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());

// add your fragments
adapter.addFrag(new SampleFragment(), "Tab1");
adapter.addFrag(new SampleFragment(), "Tab2");
adapter.addFrag(new SampleFragment(), "Tab3");

// set adapter on viewpager
viewPager.setAdapter(adapter);

XML layout

<?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"
    android:orientation="vertical">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tablayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <androidx.viewpager.widget.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

</LinearLayout>

Note If you are not using AndroidX yet, you need to change following in layout.

  • Change com.google.android.material.tabs.TabLayout to android.support.design.widget.TabLayout
  • Chagne androidx.viewpager.widget.ViewPager to android.support.v4.view.ViewPager

But I'll strongly recommend to migrate to AndroidX, see @this answer to understand why.

And this is common ViewPagerAdapter for all your Viewpager in app.

public class ViewPagerAdapter extends FragmentStatePagerAdapter {
    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();
    }

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

    public void addFrag(Fragment fragment) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add("");
    }

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

Important Related Links

  • Difference between getSupportFragmentManager() and getChildFragmentManager()?
  • getSupportFragmentManager() versus getFragmentManager() in android 3.0+
  • Difference between FragmentPagerAdapter and FragmentStatePagerAdapter


来源：https://stackoverflow.com/questions/17227855/tabhost-with-fragments-and-fragmentactivity

标签
android
android-fragments
android-tabhost
android-fragmentactivity
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