탐색 모음에서 조각 전환을 수행 할 수 없습니다.

7 개의 탭으로 구성된 탭 레이아웃을 만들었습니다. 내 앱에는 탐색 창도 있습니다. 드로어가 잘 열리지 만 탐색 드로어에서 항목을 선택하면 앱이 강제로 닫힙니다. 아래는 내 주요 활동입니다 .Java

public class MainActivity extends AppCompatActivity {
    private static final String TAG_HOME = "home";
    private static final String TAG_HISTORY = "history";
    private static final String TAG_LOCATION = "location";
    private static final String TAG_DEVELOPMENTS = "developments";
    private static final String TAG_DONATIONS = "donations";
    private static final String TAG_FEEDBACK = "feedback";
    private static final String TAG_RESOURCES = "resources";
    private static final String TAG_CONTACTUS = "contactus";
    public static String CURRENT_TAG = TAG_HOME;
    private DrawerLayout mDrawerLayout;
    // flag to load home fragment when user presses back key
    public static int navItemIndex = 0;
    private boolean shouldLoadHomeFragOnBackPress = true;
    private Handler mHandler;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // Adding Toolbar to Main screen
        mHandler = new Handler();
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        // Setting ViewPager for each Tabs
        ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);
        // Set Tabs inside Toolbar
        TabLayout tabs = (TabLayout) findViewById(R.id.tabs);
        tabs.setupWithViewPager(viewPager);
        // Create Navigation drawer and inlfate layout
        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer);

        // Set behavior of Navigation drawer
        navigationView.setNavigationItemSelectedListener(
                new NavigationView.OnNavigationItemSelectedListener() {


                    @Override
                    public boolean onNavigationItemSelected(MenuItem menuItem) {

                        //Check to see which item was being clicked and perform appropriate action
                        switch (menuItem.getItemId()) {
                            //Replacing the main content with ContentFragment Which is our Inbox View;
                            case R.id.nav_home:
                                navItemIndex = 0;
                                CURRENT_TAG = TAG_HOME;
                                break;
                            case R.id.nav_history:
                                navItemIndex = 1;
                                CURRENT_TAG = TAG_HISTORY;
                                break;
                            case R.id.nav_location:
                                navItemIndex = 2;
                                CURRENT_TAG = TAG_LOCATION;
                                break;
                            case R.id.nav_developments:
                                navItemIndex = 3;
                                CURRENT_TAG = TAG_DEVELOPMENTS;
                                break;
                            case R.id.nav_donations:
                                navItemIndex = 4;
                                CURRENT_TAG = TAG_DONATIONS;
                                break;
                            case R.id.nav_resources:
                                navItemIndex = 5;
                                CURRENT_TAG = TAG_RESOURCES;
                                break;
                            case R.id.nav_feedback:
                                navItemIndex = 6;
                                CURRENT_TAG = TAG_FEEDBACK;
                                break;
                            case R.id.nav_contactus:
                                navItemIndex = 7;
                                CURRENT_TAG = TAG_CONTACTUS;
                                break;

                            default:
                                navItemIndex = 0;
                        }

                        //Checking if the item is in checked state or not, if not make it in checked state
                        if (menuItem.isChecked()) {
                            menuItem.setChecked(false);
                        } else {
                            menuItem.setChecked(true);
                        }
                        menuItem.setChecked(true);

                        loadHomeFragment();

                        return true;
                    }
                });
        // Adding Floating Action Button to bottom right of main view

    }

    private void loadHomeFragment() {

        // if user select the current navigation menu again, don't do anything
        // just close the navigation drawer
        if (getSupportFragmentManager().findFragmentByTag(CURRENT_TAG) != null) {
            mDrawerLayout.closeDrawers();

            // show or hide the fab button

            return;
        }

        Runnable mPendingRunnable = new Runnable() {
            @Override
            public void run() {
                // update the main content by replacing fragments
                Fragment fragment = getHomeFragment();
                FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();

                fragmentTransaction.replace(R.id.tabs, fragment, CURRENT_TAG);
                fragmentTransaction.commitAllowingStateLoss();
            }
        };

        // If mPendingRunnable is not null, then add to the message queue
        if (mPendingRunnable != null) {
            mHandler.post(mPendingRunnable);
        }

        mDrawerLayout.closeDrawers();

        invalidateOptionsMenu();
    }

    private Fragment getHomeFragment() {
        switch (navItemIndex) {
            case 0:
                // home
                one_main oneMain = new one_main();
                return oneMain;
            case 1:

                one_fragment oneFragment = new one_fragment();
                return oneFragment;
            case 2:

                two_location twoLocation = new two_location();
                return twoLocation;
            case 3:

                four_future fourFuture = new four_future();
                return fourFuture;

            case 4:

                three_donation threeDonation = new three_donation();
                return threeDonation;

            case 5:

                six_download sixDownload = new six_download();
                return sixDownload;
            case 6:

                five_feedback fiveFeedback = new five_feedback();
                return fiveFeedback;

            case 7:

                seven_contact sevenContact = new seven_contact();
                return sevenContact;
            default:
                return new one_main();
        }
    }



    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        } else if (id == android.R.id.home) {
            mDrawerLayout.openDrawer(GravityCompat.START);
        }
        return super.onOptionsItemSelected(item);
    }
//Checking if the item is in checked state or not, if not make it in checked state

    @Override
    public void onBackPressed() {
        if (mDrawerLayout.isDrawerOpen(GravityCompat.START)) {
            mDrawerLayout.closeDrawers();
            return;
        }
        if (shouldLoadHomeFragOnBackPress) {
            // checking if user is on other navigation menu
            // rather than home
            if (navItemIndex != 0) {
                navItemIndex = 0;
                CURRENT_TAG = TAG_HOME;
                loadHomeFragment();
                return;
            }
        }

        super.onBackPressed();
    }

}

내 menu_navigation.xml은 다음과 같습니다.

<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <group android:checkableBehavior="single">
        <item
            android:id="@+id/nav_home"
       android:icon="@drawable/ic_home_black_24dp"
        android:tint="@color/button_grey"
        android:title="Home" />
    <item
        android:id="@+id/nav_history"
        android:icon="@drawable/ic_bookmark_border_black_24dp"
        android:tint="@color/button_grey"
        android:title="History" />
    <item
        android:id="@+id/nav_location"
        android:icon="@drawable/ic_bookmark_border_black_24dp"
        android:tint="@color/button_grey"
        android:title="Location" />

        <item

            android:id="@+id/nav_developments"
            android:icon="@drawable/ic_bookmark_border_black_24dp"
            android:tint="@color/button_grey"
            android:title="Developments" />
        <item
            android:id="@+id/nav_donations"
            android:icon="@drawable/ic_bookmark_border_black_24dp"
            android:tint="@color/button_grey"
            android:title="Donations" />
        <item
            android:id="@+id/nav_resources"
            android:icon="@drawable/ic_bookmark_border_black_24dp"
            android:tint="@color/button_grey"
            android:title="Resources" />
        <item
            android:id="@+id/nav_feedback"
            android:icon="@drawable/ic_bookmark_border_black_24dp"
            android:tint="@color/button_grey"
            android:title="Feedback" />

        <item
            android:id="@+id/nav_contactus"
            android:icon="@drawable/ic_bookmark_border_black_24dp"
            android:tint="@color/button_grey"
            android:title="Contact Us" />
</group>
</menu>

내 활동 main.xml

<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/drawer"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.design.widget.CoordinatorLayout
        android:id="@+id/main_content"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <android.support.design.widget.AppBarLayout
            android:id="@+id/appbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                android:background="?attr/colorPrimary"
                app:layout_scrollFlags="scroll|enterAlways"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

            <android.support.design.widget.TabLayout
                android:id="@+id/tabs"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:tabGravity="fill"
                app:tabMode="scrollable"
                app:tabTextAppearance="@style/TabTextAppearance"/>
        </android.support.design.widget.AppBarLayout>
        <android.support.v4.view.ViewPager
            android:id="@+id/viewpager"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    </android.support.design.widget.CoordinatorLayout>
    <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/navheader"
        app:menu="@menu/menu_navigation" />
</android.support.v4.widget.DrawerLayout>

누군가 탐색 메뉴에서 항목을 선택할 때 앱이 닫히는 이유를 말해 줄 수 있습니까?