将贴图添加到片段会产生异常

时间：2014-02-09 21:06:19

标签： android

在此处的this示例后，我尝试在片段中插入地图。这是我的片段类：

package com.example.mapfragdemo;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

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

public class MapPageFragment extends Fragment {

private SupportMapFragment fragment;
private GoogleMap map;

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

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    FragmentManager fm = getChildFragmentManager();
    fragment = (SupportMapFragment) fm.findFragmentById(R.id.map);
    if (fragment == null) {
        fragment = SupportMapFragment.newInstance();
        fm.beginTransaction().replace(R.id.map, fragment).commit();
    }
}

@Override
public void onResume() {
    super.onResume();
    if (map == null) {
        map = fragment.getMap();
        map.addMarker(new MarkerOptions().position(new LatLng(0, 0)));
    }
}
}

这是我的主要活动：

package com.example.mapfragdemo;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

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

}

activity_main.xml中

<RelativeLayout 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"
tools:context=".MainActivity" >

<fragment
    android:id="@+id/fragment1"
    android:name="com.example.mapfragdemo.MapPageFragment"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
     />


</RelativeLayout>

map_fragment_layout.xml 

<?xml version="1.0" encoding="utf-8"?>
<fragment
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:map="http://schemas.android.com/apk/res-auto"
android:id="@+id/map"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
class="com.google.android.gms.maps.SupportMapFragment"
map:uiCompass="true"
map:mapType= "normal"
map:uiRotateGestures="true"
map:uiScrollGestures="true"
map:uiTiltGestures="true"
map:uiZoomControls="true"
map:uiZoomGestures="true" />

我得到以下异常：

02-10 02:23:40.731: E/Trace(23341): error opening trace file: No such file or directory (2)
02-10 02:23:40.731: D/ActivityThread(23341): setTargetHeapUtilization:0.25
02-10 02:23:40.731: D/ActivityThread(23341): setTargetHeapIdealFree:8388608
02-10 02:23:40.731: D/ActivityThread(23341): setTargetHeapConcurrentStart:2097152
02-10 02:23:40.841: D/AndroidRuntime(23341): Shutting down VM
02-10 02:23:40.841: W/dalvikvm(23341): threadid=1: thread exiting with uncaught exception (group=0x40d65378)
02-10 02:23:40.851: E/AndroidRuntime(23341): FATAL EXCEPTION: main
02-10 02:23:40.851: E/AndroidRuntime(23341): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mapfragdemo/com.example.mapfragdemo.MainActivity}: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2071)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2096)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.ActivityThread.access$600(ActivityThread.java:138)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1207)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.os.Looper.loop(Looper.java:213)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.ActivityThread.main(ActivityThread.java:4787)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at java.lang.reflect.Method.invokeNative(Native Method)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at java.lang.reflect.Method.invoke(Method.java:511)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at dalvik.system.NativeStart.main(Native Method)
02-10 02:23:40.851: E/AndroidRuntime(23341): Caused by: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:262)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.Activity.setContentView(Activity.java:1867)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at com.example.mapfragdemo.MainActivity.onCreate(MainActivity.java:12)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.Activity.performCreate(Activity.java:5008)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2035)
02-10 02:23:40.851: E/AndroidRuntime(23341):    ... 11 more
02-10 02:23:40.851: E/AndroidRuntime(23341): Caused by: java.lang.ClassCastException: com.example.mapfragdemo.MapPageFragment cannot be cast to android.app.Fragment
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.Fragment.instantiate(Fragment.java:577)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.Fragment.instantiate(Fragment.java:552)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.app.Activity.onCreateView(Activity.java:4656)
02-10 02:23:40.851: E/AndroidRuntime(23341):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:680)
02-10 02:23:40.851: E/AndroidRuntime(23341):    ... 21 more

为什么会出现上述异常。任何帮助表示赞赏。

1 个答案:

答案 0 :(得分：1)

  

为什么会出现上述异常

错误消息是：

Caused by: java.lang.ClassCastException: com.example.mapfragdemo.MapPageFragment cannot be cast to android.app.Fragment

您的MapPageFragment延伸android.support.v4.app.Fragment，而不是android.app.Fragment。

总体而言，您正在使用片段backport（MapPageFragment的两个地方，以及布局中对SupportMapFragment的引用），而在另一个地方（您的Activity），您没有使用后退。我猜你应该MainActivity延长FragmentActivity而不是Activity。

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