谷歌地图API V2定制MapFragment + SimpleFragment [英] Google Maps API v2 Custom MapFragment + SimpleFragment

问题描述

我需要创建一个简单的应用程序包含
1.自MapFragment能够显示当前的位置（LocationListener的？），两个标记等
2.简单的空片段。

I need to create a simple application which contain 1. Custom MapFragment which can display current location (LocationListener?), two markers, etc. 2. Simple empty Fragments.

应用程序不能使用支持V4（SDK 11+）/ FragmentActivity。

The application must not use support v4 (sdk 11+) / FragmentActivity.

空片段。

XML：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/black" >
</RelativeLayout>

类：

public class FirstFragment extends Fragment{

public FirstFragment() {
}

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

地图片段（尽量做到单）。

Map fragment (try to make it singleton).

XML：

<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/map"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  class="com.google.android.gms.maps.MapFragment"/>

类

public class ThirdMapFragment extends MapFragment {
public static MapFragment instance;

@Override
public View onCreateView(LayoutInflater arg0, ViewGroup arg1, Bundle arg2) {
    View view;
    view = arg0.inflate(R.layout.map_fragment, arg1, false);
    return view;
}

public static MapFragment getInstance() {
    if (instance == null) {
        instance = newInstance();
    }
    // NullPointerException in getMap() ???
    // instance.getMap().addMarker(new MarkerOptions().position(new LatLng(41.1, 39)));
    return instance;
}

@Override
public void onCreate(Bundle arg0) {
    super.onCreate(arg0);
}
}

主要活动：

public class ActivityMain extends Activity implements OnClickListener {
FragmentManager fragmentManager;
FragmentTransaction transaction;
FirstFragment firstFragment;
MapFragment mapFragment;

// Buttons
Button b4;

int i = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    fragmentManager = getFragmentManager();
    transaction = fragmentManager.beginTransaction();

    b4 = (Button) findViewById(R.id.button4);

    b1.setOnClickListener(this);

    firstFragment = new FirstFragment();
    mapFragment =  ThirdMapFragment.getInstance();

}

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

@Override
public void onClick(View v) {
    makeTransaction(v.getId());
}



private void makeTransaction(int id) {
    i++;
    transaction = fragmentManager.beginTransaction();
    if (i == 1) {
        transaction.replace(R.id.relativeLayout, firstFragment).commit();
    } else if (i == 2) {
        transaction.replace(R.id.relativeLayout, secondFragment).commit();
    } else {
    transaction.replace(R.id.relativeLayout, mapFragment).commit();
        i = 0;
    }
}
}

R.id.relativeLayout - 布局main.xml中

R.id.relativeLayout - Layout in main.xml

但我不看地图（空屏，变焦按钮），以及如何使LocationListener的？ THX。

But I do not see the map (empty screen with zoom buttons) and how to make LocationListener? Thx.

推荐答案

不创建视图但，这就是为什么的GetMap（）返回null，地图不存在，把你的code在onResume

the view is not created yet that's why getMap() returns null, map doesn't exist, put your code in onResume

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