Android的回调片段失败,失败不能转换为android.content.Context [英] android callback fails in fragment fails cannot be cast to android.content.Context
问题描述
我有一个回调类gaGPS需要,我认为这是一个正常的活动正常工作的上下文,但是当我在一个片段使用失败
这是我的接口类
公共类gaGPS扩展服务实现LocationListener的{私人最终上下文mContext;//声明一个位置管理
受保护的LocationManager的LocationManager;私人gaGPSinterface gpsu;公共接口gaGPSinterface {
公共无效locationChanged(位置newloc);
}
公共gaGPS(上下文C,gaGPSinterface gpsiface){
mCallback = gpsiface;
// mContext =(上下文)gpsiface;
mContext = C;
的LocationManager =(的LocationManager)mContext.getSystemService(Context.LOCATION_SERVICE);
}
剪断
我使用这个FragmentActivity类启动片段
公共类gaDetailsActivity扩展FragmentActivity {@覆盖
保护无效的onCreate(捆绑savedInstanceState){
// TODO自动生成方法存根
super.onCreate(savedInstanceState);
的setContentView(R.layout.gpsfragment);}
这里是gpsfragment.xml
<?XML版本=1.0编码=UTF-8&GT?;
< LinearLayout中的xmlns:机器人=http://schemas.android.com/apk/res/android
的xmlns:工具=http://schemas.android.com/tools
机器人:layout_width =match_parent
机器人:layout_height =match_parent
工具:gpsfragment上下文=>
<片段
机器人:ID =@ + ID / gpsTestFragLayout
机器人:名字=id.wilsononline.gcadroid.gpsfragment
机器人:layout_width =0dp
机器人:layout_height =match_parent
机器人:layout_weight =1/>
以下是我使用的片段
公共类gpsfragment扩展片段实现gaGPS.gaGPSinterface {私人gaGPS GPS;@覆盖
公共无效locationChanged(位置newloc){
// TODO自动生成方法存根}@覆盖
公共无效onAttach(活动活动){
// TODO自动生成方法存根
super.onAttach(活动);
}
@覆盖
公共查看onCreateView(LayoutInflater充气器,容器的ViewGroup,
捆绑savedInstanceState){
// TODO自动生成方法存根
查看rootView = inflater.inflate(R.layout.gpsdetails,集装箱,FALSE);
((的TextView)rootView.findViewById(R.id.gpsText1))的setText(测试片段); 上下文C = getActivity()getApplicationContext()。 GPS =新gaGPS(C,(gaGPSinterface)getActivity()); 返回rootView;
}
}
我得到的错误是:
java.lang.ClassCastException:com.test.app.gpsfragment不能转换为android.content.Context
更多更全面的输出:
E / AndroidRuntime(3118):android.view.InflateException:通过引起二进制XML文件行#8:错误充气类片段
E / AndroidRuntime(3118):在android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
E / AndroidRuntime(3118):在android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
E / AndroidRuntime(3118):在android.view.LayoutInflater.inflate(LayoutInflater.java:489)
E / AndroidRuntime(3118):在android.view.LayoutInflater.inflate(LayoutInflater.java:396)
E / AndroidRuntime(3118):在android.view.LayoutInflater.inflate(LayoutInflater.java:352)
E / AndroidRuntime(3118):在com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:256)
E / AndroidRuntime(3118):在android.com.test.app.Activity.setContentView(Activity.java:1867)
E / AndroidRuntime(3118):在id.wilsononline.gcadroid.gaDetailsActivity.onCreate(gaDetailsActivity.java:12)
E / AndroidRuntime(3118):在android.com.test.app.Activity.performCreate(Activity.java:5008)
E / AndroidRuntime(3118):在android.com.test.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
E / AndroidRuntime(3118):在android.com.test.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
E / AndroidRuntime(3118):11 ...更多
E / AndroidRuntime(3118):java.lang.ClassCastException:致com.test.com.test.app.gaDetailsActivity不能转换为id.wilsononli
ne.gcadroid.gaGPS $ gaGPSinterface
E / AndroidRuntime(3118):在com.test.com.test.app.gpsfragment.onCreateView(gpsfragment.java:49)
E / AndroidRuntime(3118):在android.support.v4.com.test.app.Fragment.performCreateView(Fragment.java:1460)
E / AndroidRuntime(3118):在android.support.v4.com.test.app.FragmentManagerImpl.moveToState(FragmentManager.java:884)
E / AndroidRuntime(3118):在android.support.v4.com.test.app.FragmentManagerImpl.moveToState(FragmentManager.java:1066)
E / AndroidRuntime(3118):在android.support.v4.com.test.app.FragmentManagerImpl.addFragment(FragmentManager.java:1168)
E / AndroidRuntime(3118):在android.support.v4.com.test.app.FragmentActivity.onCreateView(FragmentActivity.java:280)
E / AndroidRuntime(3118):在android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:676)
E / AndroidRuntime(3118):21 ...更多
公共gaGPS(gaGPSinterface gpsu){
this.mContext =(上下文)gpsu;
this.gpsu = gpsu;
// ...
}
在这里,你想投 gpsu
到上下文
。它不是一;这是一个片段
。你应该通过上下文
和 gaGPSinterface
分开:
公共gaGPS(上下文C,gaGPSinterface gpsu){
this.mContext = C;
this.gpsu = gpsu;
// ...
}
然后,使用称之为 .getActivity()
(返回一个活动
的一个子类<$ C从$ C>上下文)的片段
:
GPS =新gaGPS(getActivity(),这一点);
I have a callback class gaGPS which requires I think is a context which works fine in a normal activity but when I use in a Fragment it fails
here is my interface class
Public class gaGPS extends Service implements LocationListener {
private final Context mContext;
// Declaring a Location Manager
protected LocationManager locationManager;
private gaGPSinterface gpsu;
public interface gaGPSinterface {
public void locationChanged(Location newloc);
}
public gaGPS(Context c, gaGPSinterface gpsiface) {
mCallback = gpsiface;
//mContext = (Context) gpsiface;
mContext = c;
locationManager = (LocationManager) mContext.getSystemService(Context.LOCATION_SERVICE);
}
snip
I'm launching the Fragment using this FragmentActivity class
public class gaDetailsActivity extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.gpsfragment);
}
here is the gpsfragment.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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=".gpsfragment" >
<fragment
android:id="@+id/gpsTestFragLayout"
android:name="id.wilsononline.gcadroid.gpsfragment"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1" />
the following is the Fragment I'm using
public class gpsfragment extends Fragment implements gaGPS.gaGPSinterface {
private gaGPS gps;
@Override
public void locationChanged(Location newloc) {
// TODO Auto-generated method stub
}
@Override
public void onAttach(Activity activity) {
// TODO Auto-generated method stub
super.onAttach(activity);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View rootView = inflater.inflate(R.layout.gpsdetails, container, false);
((TextView) rootView.findViewById(R.id.gpsText1)).setText("testing fragment");
Context c = getActivity().getApplicationContext();
gps = new gaGPS(c, (gaGPSinterface) getActivity());
return rootView;
}
}
errors I'm getting are : java.lang.ClassCastException: com.test.app.gpsfragment cannot be cast to android.content.Context
more fuller output:
E/AndroidRuntime( 3118): Caused by: android.view.InflateException: Binary XML file line #8: Error inflating class fragment
E/AndroidRuntime( 3118): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
E/AndroidRuntime( 3118): at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
E/AndroidRuntime( 3118): at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
E/AndroidRuntime( 3118): at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
E/AndroidRuntime( 3118): at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
E/AndroidRuntime( 3118): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:256)
E/AndroidRuntime( 3118): at android.com.test.app.Activity.setContentView(Activity.java:1867)
E/AndroidRuntime( 3118): at id.wilsononline.gcadroid.gaDetailsActivity.onCreate(gaDetailsActivity.java:12)
E/AndroidRuntime( 3118): at android.com.test.app.Activity.performCreate(Activity.java:5008)
E/AndroidRuntime( 3118): at android.com.test.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
E/AndroidRuntime( 3118): at android.com.test.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
E/AndroidRuntime( 3118): ... 11 more
E/AndroidRuntime( 3118): Caused by: java.lang.ClassCastException: com.test.com.test.app.gaDetailsActivity cannot be cast to id.wilsononli
ne.gcadroid.gaGPS$gaGPSinterface
E/AndroidRuntime( 3118): at com.test.com.test.app.gpsfragment.onCreateView(gpsfragment.java:49)
E/AndroidRuntime( 3118): at android.support.v4.com.test.app.Fragment.performCreateView(Fragment.java:1460)
E/AndroidRuntime( 3118): at android.support.v4.com.test.app.FragmentManagerImpl.moveToState(FragmentManager.java:884)
E/AndroidRuntime( 3118): at android.support.v4.com.test.app.FragmentManagerImpl.moveToState(FragmentManager.java:1066)
E/AndroidRuntime( 3118): at android.support.v4.com.test.app.FragmentManagerImpl.addFragment(FragmentManager.java:1168)
E/AndroidRuntime( 3118): at android.support.v4.com.test.app.FragmentActivity.onCreateView(FragmentActivity.java:280)
E/AndroidRuntime( 3118): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:676)
E/AndroidRuntime( 3118): ... 21 more
public gaGPS(gaGPSinterface gpsu) {
this.mContext = (Context) gpsu;
this.gpsu = gpsu;
// ...
}
Here, you're trying to cast gpsu
to a Context
. It's is not one; it's a Fragment
. You should pass the Context
and gaGPSinterface
separately:
public gaGPS(Context c, gaGPSinterface gpsu) {
this.mContext = c;
this.gpsu = gpsu;
// ...
}
Then, call it using .getActivity()
(which returns an Activity
, a subclass of Context
) from the Fragment
:
gps = new gaGPS(getActivity(), this);
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