Android后退按钮关闭整个应用

Question

我有一个主要活动（OrganizerMainActivity），其RecyclerView。当您单击列表项时，我会以这种方式启动一个新的活动：

@Override
public void onListFragmentInteraction(EventModel item) {
    Intent eventDetailIntent = new Intent(this, EventDetailActivity.class);
    eventDetailIntent.putExtra(EVENT_ITEM, item);
    startActivity(eventDetailIntent);
}

在我来到EventDetailActivity之后，如果按下后退按钮，整个应用程序都会关闭。但是，我需要该应用返回OrganizerMainActivity。

我的AndroidManifest.xml也是：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="app.iamindia.com.iamindia">

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CAMERA" />
"
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

<application
    android:name=".MainApplication"
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity
        android:name=".SignInActivity"
        android:configChanges="orientation"
        android:screenOrientation="portrait">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".SignUpActivity" />
    <activity android:name=".UserTypeActivity" />
    <activity
        android:name=".OrganizerMainActivity"
        android:configChanges="orientation"
        android:label="@string/title_activity_main"
        android:screenOrientation="portrait"
        android:theme="@style/AppTheme" />
    <activity
        android:name=".ForgotPasswordActivity"
        android:configChanges="orientation"
        android:screenOrientation="portrait" />
    <activity
        android:name=".SignUpOneActivity"
        android:label="SignUpActivity"
        android:theme="@style/AppTheme" />
    <activity
        android:name=".VolunteerMainActivity"
        android:configChanges="orientation"
        android:label="@string/title_activity_volunteer_main"
        android:screenOrientation="portrait"
        android:theme="@style/AppTheme" />
    <activity android:name=".SignUpTwoActivity" />
    <activity
        android:name=".CreateEventActivity"
        android:configChanges="orientation"
        android:screenOrientation="portrait" />
    <activity
        android:name="com.theartofdev.edmodo.cropper.CropImageActivity"
        android:theme="@style/Base.Theme.AppCompat" />

    <meta-data
        android:name="com.google.android.geo.API_KEY"
        android:value="AIzaSyCh0sjei_PUUCGexYBZtGbDjN_pZGNjCXs" />

    <activity
        android:name=".EventDetailActivity"
        android:label="@string/title_activity_event_detail"
        android:theme="@style/AppTheme"
        android:parentActivityName=".OrganizerMainActivity"></activity>
</application>

更新：EventDetailActivity

package app.iamindia.com.iamindia;

import android.app.Activity;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.app.NavUtils;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;

import app.iamindia.com.iamindia.models.EventModel;
import app.iamindia.com.iamindia.models.UserModel;
import app.iamindia.com.iamindia.services.UserService;

public class EventDetailActivity extends AppCompatActivity {

    private static final String EVENT_ITEM = "EVENT_ITEM";
    private EventModel item;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_event_detail);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setTitle("Event Detail");

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        if (getIntent().getExtras().getParcelable(EVENT_ITEM) != null) {
            item = getIntent().getExtras().getParcelable(EVENT_ITEM);
        }
    }

    @Override
    public void onBackPressed() {
        super.onBackPressed();
    }

    private void getOrganizerProfileDetails(String organizerId) {
        UserService.getInstance().getUserProfile(organizerId, new UserService.AsyncListener<UserModel>() {
            @Override
            public void onSuccess(UserModel userModel) {

            }

            @Override
            public void onFailure(@NonNull Exception e) {

            }
        });
    }

}

更新：OrganizerMainActivity

package app.iamindia.com.iamindia;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.NavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
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.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;

import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

import java.util.List;

import app.iamindia.com.iamindia.models.EventModel;
import app.iamindia.com.iamindia.services.EventService;
import app.iamindia.com.iamindia.services.UserService;

public class OrganizerMainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener, HomeFragment.OnFragmentInteractionListener,
        EventListFragment.OnListFragmentInteractionListener, ProfileFragment.OnFragmentInteractionListener,
        LeaderBoardFragment.OnFragmentInteractionListener{

    private static int navIndex = 0;
    private static String currentTag = "home";
    private String[] activityTitles;
    private NavigationView navigationView;
    private static final String EVENT_ITEM = "EVENT_ITEM";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_organizer_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        if (UserService.getInstance().getCurrentUser().getType().equalsIgnoreCase("organizer")) {
            fab.setVisibility(View.VISIBLE);
            fab.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Intent newEventIntent = new Intent(OrganizerMainActivity.this, CreateEventActivity.class);
                    startActivity(newEventIntent);
                }
            });
        } else {
            fab.setVisibility(View.GONE);
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

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

        activityTitles = getResources().getStringArray(R.array.nav_item_titles);

        // load home fragment by default
        if (savedInstanceState == null) {
            navIndex = 0;
            currentTag = "home";
            loadHomeFragment();
        }

        EventService.getInstance().fetchEvents(new OnSuccessListener<List<EventModel>>() {
            @Override
            public void onSuccess(List<EventModel> eventModels) {
            }
        });
    }

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

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

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        displayFragment(item.getItemId());
        return true;
    }

    private void displayFragment(int id) {
        Fragment fragment;

        switch(id) {
            case R.id.organizer_home:
                navIndex = 0;
                fragment = new HomeFragment();
                setTitle("Home");
                break;
            case R.id.organizer_leaderboard:
                navIndex = 1;
                fragment = new LeaderBoardFragment();
                setTitle("Leader Board");
                break;
            default:
                fragment = new HomeFragment();
        }

        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);
    }

    private void loadHomeFragment() {
        selectNavMenu();
        setToolbarTitle();

        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.content_frame, new HomeFragment());
        ft.commit();
    }

    private void selectNavMenu() {
        navigationView.getMenu().getItem(navIndex).setChecked(true);
    }

    private void setToolbarTitle() {
//        getSupportActionBar().setTitle(activityTitles[navIndex]);
    }



    @Override
    public void onFragmentInteraction(Uri uri){
        //you can leave it empty
    }

    @Override
    public void onListFragmentInteraction(EventModel item) {
        Intent eventDetailIntent = new Intent(this, EventDetailActivity.class);
        eventDetailIntent.putExtra(EVENT_ITEM, item);
        startActivity(eventDetailIntent);
    }
}

有人可以指导我吗？