谷歌地图不显示在android系统

Question

标记我下面toturial在Google Developers网站给出在MapsActivity.java

package com.pro.soft.inzi.track_trace; 

import android.content.Intent; 
import android.os.Bundle; 
import android.support.v4.app.FragmentActivity; 
import android.view.View; 
import android.widget.Button; 

import com.google.android.gms.maps.CameraUpdateFactory; 
import com.google.android.gms.maps.GoogleMap; 
import com.google.android.gms.maps.OnMapReadyCallback; 
import com.google.android.gms.maps.model.LatLng; 
import com.google.android.gms.maps.model.MarkerOptions; 

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback { 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_maps); 

     Button sign_in_btn = (Button) findViewById(R.id.b1); 
     sign_in_btn.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       Intent intent = new Intent(getApplicationContext(),Live.class); 
       startActivity(intent); 
      } 
     }); 
     Button history_btn = (Button) findViewById(R.id.b2); 
     history_btn.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       Intent intent = new Intent(getApplicationContext(), History.class); 
       startActivity(intent); 
      } 
     }); 
    } 
    @Override 
    public void onMapReady(GoogleMap googleMap) { 

     // Add a marker in Pakistan and move the camera 
     LatLng Pakistan = new LatLng(31, 71); 
     googleMap.addMarker(new MarkerOptions().position(Pakistan).title("Marker in Pakistan")); 
     googleMap.moveCamera(CameraUpdateFactory.newLatLng(Pakistan)); 
    } 
} 

这些都是AndroidManifest.xml文件

<uses-permission android:name="android.permission.INTERNET" /> 
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> 
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> 
    <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" /> 
    <!-- 
The ACCESS_COARSE/FINE_LOCATION permissions are not required to use 
     Google Maps Android API v2, but are recommended. 
    --> 
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> 
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> 

    <!-- 
    To retrieve OAuth 2.0 tokens or invalidate tokens to disconnect a user. This disconnect 
    option is required to comply with the Google+ Sign-In developer policies 
    --> 
    <uses-permission android:name="android.permission.USE_CREDENTIALS" /> 
    <!-- To retrieve the account name (email) as part of sign-in: --> 
    <uses-permission android:name="android.permission.GET_ACCOUNTS" /> 
    <!-- To auto-complete the email text field in the login form with the user's emails --> 
    <uses-permission android:name="android.permission.READ_PROFILE" /> 
    <uses-permission android:name="android.permission.READ_CONTACTS" /> 

    <permission 
     android:name="your.package.name.permission.MAPS_RECEIVE" 
     android:protectionLevel="signature" /> 
    <uses-permission android:name="your.package.name.permission.MAPS_RECEIVE"/> 
    <uses-feature 
     android:glEsVersion="0x00020000" 
     android:required="true"/> 

的一切权限，该代码除了一个Marker做工精细我遵循这个网站上的相关问题和网络上的说明但是都是徒劳的。
标记未显示在地图中 请告诉我什么是错的。

编辑：这里是activity_maps代码，包括MapFragment在它

<RelativeLayout 
    android:layout_height="match_parent" 
    android:layout_width="match_parent" 
    xmlns:android="http://schemas.android.com/apk/res/android"> 

    <Button 
     android:id="@+id/b1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="@string/b1_text" 
     /> 
    <Button 
     android:id="@+id/b2" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="@string/b2_text" 
     android:layout_toRightOf="@+id/b1"/> 
    <Button android:id="@+id/b3" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="@string/b3_text" 
     android:layout_toRightOf="@+id/b2"/> 

    <RelativeLayout 
     android:id="@+id/mainP" 
     android:layout_width="match_parent" 
     android:layout_height="400dp" 
     android:layout_below="@+id/b2"> 

     <fragment 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:id="@+id/map" 
      tools:context=".MapsActivity" 
      android:name="com.google.android.gms.maps.MapFragment" /> 

    </RelativeLayout> 
    <EditText 
     android:id="@+id/info" 
     android:layout_width="160dp" 
     android:layout_height="wrap_content" 
     android:hint="@string/info_1" 
     android:layout_below="@+id/mainP" 
     /> 
    <EditText 
     android:layout_width="160dp" 
     android:layout_height="wrap_content" 
     android:hint="@string/info_2" 
     android:layout_below="@+id/mainP" 
     android:layout_toRightOf="@+id/info"/> 
</RelativeLayout> 

Answer 1

首先，你应该初始化您googleMap Object在onCreate(....)

SupportMapFragment googleMap=(SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map); 

Answer 2

试试这个

googleMap.addMarker(new MarkerOptions() 
      .position(Pakistan) 
      .title("Marker in Pakistan") 
      .icon(BitmapDescriptorFactory 
      .defaultMarker(BitmapDescriptorFactory.HUE_GREEN))); 

Answer 3

add this ,it works 

googleMap.addMarker（新的MarkerOptions（）.POSITION（新经纬度（纬度，经度））。title（“我的位置”）.snippet（“kochi”）。draggable（true））;

Answer 4

你onMapReady(GoogleMap googleMap)不会被调用。 你需要调用getMapAsync在地图上的片段设置OnMapReadyCallback

从the documentation

公共无效getMapAsync（OnMapReadyCallback回调）

设置将被触发时的GoogleMap的回调对象 实例已准备就绪可以使用。

你onCreate函数的末尾添加以下代码：

MapFragment mapFragment = (MapFragment) getFragmentManager().findFragmentById(R.id.map); 
mapFragment.getMapAsync(this);