Question

我正在创建一个Android应用程序，它有一个导航抽屉，导航项目上加载了片段。

其中一个片段包含两个选项卡，它们通过ViewPager加载另外两个片段。

一切都像预期一样正常，但当我从抽屉中选择另一个导航项时，问题就出现了。

其中一个选项卡有选项菜单，但当我转到另一个片段并返回到前一个时，选项菜单会重复。

Class LunchTabsFragment

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.view.*;

public class LunchTabsFragment extends Fragment{

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

        //Setting tabs layout
        TabLayout tabLayout = (TabLayout) v.findViewById(R.id.tabs);
        tabLayout.addTab(tabLayout.newTab().setText("Menu"));
        tabLayout.addTab(tabLayout.newTab().setText("History"));

        //Setting pages to be loaded with fragments
        final ViewPager viewPager = (ViewPager) v.findViewById(R.id.pager);
        viewPager.setAdapter(new LunchTabsPagerAdapter(getFragmentManager(), tabLayout.getTabCount()));

        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
        tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }

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

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

        return v;
    }
}

Class LunchTabsPagerAdapter

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;

public class LunchTabsPagerAdapter extends FragmentStatePagerAdapter {
    int mNumOfTabs;

    public LunchTabsPagerAdapter(FragmentManager fm, int NumOfTabs) {
        super(fm);
        this.mNumOfTabs = NumOfTabs;
    }

    @Override
    public Fragment getItem(int position) {

        switch (position) {
            case 0:
                LunchMenuFragment tab1 = new LunchMenuFragment();
                return tab1;
            case 1:
                LunchHistoryFragment tab2 = new LunchHistoryFragment();
                return tab2;
            default:
                return null;
        }
    }

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

Class MainActivity

import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.support.v4.app.FragmentTransaction;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.*;
import android.view.Menu;

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

    public static final int DRAWER_OPEN = R.string.navigation_drawer_open;
    public static final int DRAWER_CLOSE = R.string.navigation_drawer_close;

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

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar, DRAWER_OPEN, DRAWER_CLOSE);
        drawer.addDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        if (savedInstanceState == null) {
            navigationView.getMenu().performIdentifierAction(R.id.nav_lunch, 0);
        }
    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        //creating fragment object
        Fragment fragment = null;

        //initializing the fragment object which is selected
        switch (item.getItemId()) {
            case R.id.nav_lunch:
                fragment = new LunchTabsFragment();
                break;
            case R.id.nav_attendance:
                fragment = new AttendanceFragment();
                break;
            case R.id.nav_account:
                fragment = new ProfileFragment();
                break;
            case R.id.nav_logout:
                UserSessionManager.getInstance(getApplicationContext()).logout();
                break;
        }

        //replacing the fragment
        if (fragment != null) {
            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.replace(R.id.content_frame, fragment);
            ft.commit();
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);

        return true;
    }
}

Class AttendanceFragment

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.*;

public class AttendanceFragment extends Fragment {

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

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        getActivity().setTitle("Attendance");
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="horizontal">

    <android.support.design.widget.TabLayout
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimary"/>

    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="fill_parent"
        android:layout_below="@id/tabs"/>

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout 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/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <include
        layout="@layout/app_bar_sliding"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_sliding"
        app:menu="@menu/activity_sliding_drawer" />

</android.support.v4.widget.DrawerLayout>

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context="com.example.gaditek.life.MenuActivity"
    tools:showIn="navigation_view">

    <item android:id="@+id/action_search"
        android:title="Search"
        android:icon="@drawable/ic_search"
        app:showAsAction="ifRoom|collapseActionView"
        app:actionViewClass="android.support.v7.widget.SearchView" />

Class LunchMenuFragment

import android.content.DialogInterface;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.app.AlertDialog;
import android.support.v7.widget.SearchView;
import android.util.Log;
import android.view.*;
import android.view.Menu;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;

public class LunchMenuFragment extends Fragment implements View.OnClickListener {

    private ArrayList<LunchMenuItem> lunchMenuItemsArray;
    private ListView listItemView;
    private LunchMenuAdapter adapter;
    private String search;

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

        //Initializing Buttons
        Button b = (Button) v.findViewById(R.id.btnReview);
        b.setOnClickListener(this);
        Button a = (Button) v.findViewById(R.id.btnRefresh);
        a.setOnClickListener(this);

        return v;
    }

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

    @Override
    public void onPrepareOptionsMenu(android.view.Menu menu) {
        menu.findItem(R.id.action_search).setVisible(true);
        super.onPrepareOptionsMenu(menu);
    }
}

Answer 1

在我不需要选项栏的导航操作的方式中，不得不在每个片段中使用此代码

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

@Override
public void onCreateOptionsMenu(android.view.Menu menu, MenuInflater inflater) {
    super.onCreateOptionsMenu(menu, inflater);
    menu.clear();
}

Android Fragment ViewPager正在重新创建选项菜单

Class LunchTabsFragment

Class LunchTabsPagerAdapter

Class MainActivity

Class AttendanceFragment

1 个答案: