我正在开发第一款使用导航抽屉和Google地图的Android应用。我希望Google地图会在应用程序打开后立即显示，但我也希望它能够在＆＃34; New Trip＆＃34;在导航抽屉中被选中。
导航抽屉本身工作正常。但是，只要我添加了Google地图，抽屉中的任何内容都不会在点击时打开正确的布局。我试图为地图本身创建一个新的Fragment，而不是将它放在MainActivity中，但没有运气。我还关注创建导航抽屉和将GoogleMaps添加到应用程序中的几个视频教程，但他们都没有回答我的问题：
将Google地图添加到已有导航抽屉的应用时，您是否应该创建新的MapActivity.java和map.xml？如何在MainActivity中的onCreate以及稍后在导航抽屉中进行选择时显示地图？
我无法解释为什么我的导航抽屉在MainActivity中没有更改onNavigationItemSelected(MenuItem item)时停止工作：
package com.trippal.trippal;
import android.app.Dialog;
import android.app.FragmentManager;
import android.location.Address;
import android.location.Geocoder;
import android.os.Bundle;
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.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.maps.CameraUpdate;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import java.io.IOException;
import java.util.List;
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
GoogleMap mMap;
private static final int ERROR_DIALOG_REQUEST = 9001;
private static final double
CSULA_LAT = 34.065207,
CSULA_LNG = -118.170125,
LASVEGAS_LAT = 36.126750,
LASVEGAS_LNG = -115.165718;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (initMap()) {
Toast.makeText(this, "Ready to map!", Toast.LENGTH_SHORT).show();
gotoLocation(CSULA_LAT, CSULA_LNG, 14);
} else {
Toast.makeText(this, "Map not connected!", Toast.LENGTH_SHORT).show();
}
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
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 = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
}
@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) {
// Handle navigation view item clicks here.
int id = item.getItemId();
FragmentManager fragmentManager = getFragmentManager();
if (id == R.id.nav_new_trip_layout) {
fragmentManager.beginTransaction()
.replace(R.id.content_frame
, new NewTripFragment())
.commit();
} else if (id == R.id.nav_saved_trip_layout) {
fragmentManager.beginTransaction()
.replace(R.id.content_frame
, new SavedTripFragment())
.commit();
} else if (id == R.id.nav_saved_poi_layout) {
fragmentManager.beginTransaction()
.replace(R.id.content_frame
, new SavedPOIFragment())
.commit();
} else if (id == R.id.nav_pref_layout) {
fragmentManager.beginTransaction()
.replace(R.id.content_frame
, new PrefFragment())
.commit();
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
// ***** map logic *****
// checks if map service is connected
public boolean servicesOK() {
int isAvailable = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
if (isAvailable == ConnectionResult.SUCCESS) {
return true;
} else if (GooglePlayServicesUtil.isUserRecoverableError(isAvailable)) {
Dialog dialog = GooglePlayServicesUtil.getErrorDialog(isAvailable, this, ERROR_DIALOG_REQUEST);
dialog.show();
} else {
Toast.makeText(this, "Can't connect to mapping service", Toast.LENGTH_SHORT);
}
return false;
}
// initiates google map
private boolean initMap() {
if (mMap == null) {
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
mMap = mapFragment.getMap();
}
return (mMap != null);
}
// moves the camera location
private void gotoLocation(double lat, double lng, float zoom){
LatLng latLng = new LatLng(lat, lng);
CameraUpdate update = CameraUpdateFactory.newLatLngZoom(latLng, zoom);
mMap.moveCamera(update);
}
// hides softkey
private void hideSoftKeyboard(View v){
InputMethodManager imm = (InputMethodManager) getSystemService(INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(v.getWindowToken(), 0);
}
// geo location
public void geoLocate(View v) throws IOException {
hideSoftKeyboard(v);
TextView tv = (TextView) findViewById(R.id.map_editText_location);
String searchString = tv.getText().toString();
Geocoder gc = new Geocoder(this);
List<Address> list = gc.getFromLocationName(searchString, 1);
if (list.size() > 0){
Address address = list.get(0);
String locality = address.getLocality();
Toast.makeText(this, "Found: " + locality, Toast.LENGTH_SHORT).show();
double lat = address.getLatitude();
double lng = address.getLongitude();
gotoLocation(lat, lng, 15);
}
}
}
content_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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: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:paddingTop="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="com.trippal.trippal.MainActivity"
tools:showIn="@layout/app_bar_main">
<LinearLayout
android:id="@+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/map_textView_location"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/map_textView_location"
android:textSize="22dp" />
<EditText
android:id="@+id/map_editText_location"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@id/map_textView_location"
android:layout_toRightOf="@id/map_textView_location"
android:ems="6"
android:inputType="textCapWords"
android:textSize="22dp" />
<Button
android:id="@+id/button_search"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@id/map_textView_location"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:onClick="geoLocate"
android:text="@string/map_button_search" />
</RelativeLayout>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:map="http://schemas.android.com/apk/res-auto"
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>
</RelativeLayout>