我正在将一个应用程序转换到 android 并且在片段方面遇到了一些问题。
当我没有RelativeLayout并且Fragment它工作正常时，但是随着布局（相对或线性）的引入，它会崩溃。我正在尝试在地图顶部添加一些按钮，最好是覆盖而不是在其自己的空间中。
event_layout.xml：
<RelativeLayout android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/relativeLayout">
<fragment
android:id="@+id/the_map"
android:layout_width="match_parent"
android:layout_height="match_parent"
class="com.google.android.gms.maps.SupportMapFragment"/>
<Button android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:text="Start service"/>
</RelativeLayout>
MainActivity.java：
public class MainActivity extends FragmentActivity {
// Fragment TabHost as mTabHost
private FragmentTabHost mTabHost;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// set up the tabhost
mTabHost = (FragmentTabHost)findViewById(android.R.id.tabhost);
mTabHost.setup(this, getSupportFragmentManager(), R.id.realtabcontent);
mTabHost.addTab(mTabHost.newTabSpec("event").setIndicator("Event Locations",
getResources().getDrawable(R.drawable.ic_event_tab)),
EventFragment.class, null);
mTabHost.addTab(mTabHost.newTabSpec("itin").setIndicator("Itinerary",
getResources().getDrawable(R.drawable.ic_itin_tab)),
ItineraryFragment.class, null);
mTabHost.addTab(mTabHost.newTabSpec("info").setIndicator("Kendal Info",
getResources().getDrawable(R.drawable.ic_info_tab)),
KendalInfoFragment.class, null);
mTabHost.getTabWidget().setBackgroundColor(Color.WHITE);
}
@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;
}
}
事件片段.java：
public class EventFragment extends FragmentActivity {
private int userIcon, foodIcon, drinkIcon, shopIcon, otherIcon;
private GoogleMap theMap;
private LocationManager locMan;
private Marker userMarker;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View V = inflater.inflate(R.layout.event_layout, container, false);
// now run code below the inflate
if(theMap==null){
//map not instantiated yet
theMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.the_map)).getMap();
}
//theMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
//updatePlaces();
theMap.setMyLocationEnabled(true);
theMap.moveCamera( CameraUpdateFactory.newLatLngZoom(new LatLng(54.328337, -2.743149) ,14) );
JSONArray arrayResultFromURL;
// store the result of the data into the variable
arrayResultFromURL = getJSONfromURL("http://www.websitewebsitestr.org/json.php?f=all&type=dateAndTime");
try{
//Log.d("array_len", String.format("%d", arrayResultFromURL.length()));
for(int i=0;i<arrayResultFromURL.length();i++){
JSONObject json_data = arrayResultFromURL.getJSONObject(i);
// assign attributes from the JSON string to local variables
String id =json_data.getString("id");
String title =json_data.getString("title");
String strap; // define this for the try catch
// this try catch is in case the client does not
// put a strap in, title is mandatory
try{
strap =json_data.getString("strap");
}catch(Exception e){
strap = "";
}
Double lat = (double) 0;
Double lon = (double) 0;
// if the lat and long have not been entered then set them to 0
// otherwise an exception is thrown, and if it is lat and long will
// become 0, putting them down south.
try{
lat = (double) json_data.getDouble("lat");
}catch(Exception e){
lat = (double) 0;
}
try{
lon = (double) json_data.getDouble("long");
}catch(Exception e){
lon = (double) 0;
}
theMap.addMarker(new MarkerOptions()
.position(new LatLng(lat, lon))
.title(title)
.snippet(strap));
}
}catch (Exception e){
Log.e("log_tag", "error in array: " + e.toString());
}
//Log.d("log_tag", "result: " + res);
//Log.d("log_tag", "point debug!");
//Log.d("myApp", res.toString());
userIcon = R.drawable.common_signin_btn_icon_dark;
/*foodIcon = R.drawable.red_point;
drinkIcon = R.drawable.blue_point;
shopIcon = R.drawable.green_point;
otherIcon = R.drawable.purple_point;*/
//return V;
return inflater.inflate(R.layout.event_layout, container, false);
}
public static JSONArray getJSONfromURL(String url){
//initialize
InputStream is = null;
String result = "";
JSONArray jArray = null;
//http post
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
} catch (Exception e) {
Log.e("log_tag", "Error in http connection "+e.toString());
}
//convert response to string
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line);
}
is.close();
result=sb.toString();
} catch (Exception e) {
Log.e("log_tag", "Error converting result "+e.toString());
}
//try parse the string to a JSON object
try {
//Log.d("log_tag", "jresult: " + result + "finish");
jArray = new JSONArray(result);
//Log.e("log_tag", "result: " + jArray.toString());
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data "+e.toString());
}
return jArray;
}
public boolean onMarkerClick(Marker marker) {
Log.d("Debug_log", "clicked!!");
return true;
}
}
它会产生此错误：
07-01 11:00:29.428: E/AndroidRuntime(24381): FATAL EXCEPTION: main
07-01 11:00:29.428: E/AndroidRuntime(24381): java.lang.ClassCastException: co.uk.thewebsite.websitewebsitefest.EventFragment
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.support.v4.app.Fragment.instantiate(Fragment.java:394)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.support.v4.app.FragmentTabHost.doTabChanged(FragmentTabHost.java:339)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.support.v4.app.FragmentTabHost.onAttachedToWindow(FragmentTabHost.java:276)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.view.View.dispatchAttachedToWindow(View.java:6203)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1174)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1179)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1179)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:1179)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.view.ViewRoot.performTraversals(ViewRoot.java:797)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.view.ViewRoot.handleMessage(ViewRoot.java:1921)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.os.Handler.dispatchMessage(Handler.java:99)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.os.Looper.loop(Looper.java:143)
07-01 11:00:29.428: E/AndroidRuntime(24381): at android.app.ActivityThread.main(ActivityThread.java:4196)
07-01 11:00:29.428: E/AndroidRuntime(24381): at java.lang.reflect.Method.invokeNative(Native Method)
07-01 11:00:29.428: E/AndroidRuntime(24381): at java.lang.reflect.Method.invoke(Method.java:507)
07-01 11:00:29.428: E/AndroidRuntime(24381): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-01 11:00:29.428: E/AndroidRuntime(24381): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-01 11:00:29.428: E/AndroidRuntime(24381): at dalvik.system.NativeStart.main(Native Method)
我已尝试按照其他 stackoverflow 帖子中的建议使用框架，但是该应用程序崩溃或出错，我无法解决它。过去一周我在 android 方面学到了很多东西，我很高兴将来能学到更多！