Question

我在下面的代码行中遇到了类强制转换异常。我已经在下面附加了堆栈跟踪，下面的行是339，如堆栈跟踪中所述。

com.unique.may.utility.GlobalStateData gs = (com.unique.may.utility.GlobalStateData) getApplication();

在全局状态数据中，代码是

public class GlobalStateData extends Application {

private String findUsBranchEMailId;

public void setFindUsBranchEMailId(String findUsBranchEMailId) {
    this.findUsBranchEMailId = findUsBranchEMailId;
}

public String getFindUsBranchEMailId() {
    return findUsBranchEMailId;
}


}

堆栈跟踪

java.lang.ClassCastException: android.app.Application
at com.style.IntlLayout.Find.onChildClick(Find.java:339)
at android.widget.ExpandableListView.handleItemClick(ExpandableListView.java:588)
at android.widget.ExpandableListView.performItemClick(ExpandableListView.java:527)

下面是我的清单文件

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.styling.Layout"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="8" />
 <uses-permission android:name="android.permission.INTERNET" />
 <uses-permission android:name="android.permission.CALL_PHONE" />
 <uses-permission android:name="android.permission.CAMERA" />
 <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

 <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
 <uses-permission android:name="android.permission.SET_DEBUG_APP"></uses-permission>
 <support-screens
  android:largeScreens="true"
  android:normalScreens="true"
  android:smallScreens="true"
  android:anyDensity="true"/>

 <uses-library android:name="com.google.android.maps" />
 <application android:icon="@drawable/launcher"
    android:label="@string/app_name" 
    android:debuggable="true">

 <activity android:name=".Catalog" android:configChanges="orientation|keyboardHidden">    </activity>

     <activity android:name=".Feedback"    android:configChanges="orientation|keyboardHidden"></activity>

     <activity
        android:label="@string/app_name"
        android:name=".MainActivity"
        android:configChanges="orientation|keyboardHidden"  >
        <intent-filter >
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
       </activity>
   </application>


 </manifest>

期待您的回复。感谢。

Answer 1

为了使用getApplication（）函数，您必须先在Manifest中注册，Android会自动为您实例化。

<application android:name=".ApplicationName"

Answer 2

你指定了这个： http://developer.android.com/guide/topics/manifest/application-element.html#nm？

Answer 3

您可以访问下面的findUsBranchEMailId，

((GlobalStateData)getApplication()).setFindUsBranchEMailId("something");

获取它，

((GlobalStateData)getApplication()).getFindUsBranchEMailId());

另外，将您的Application类名添加到Manifest文件中的Application Tag，

<application android:icon="@drawable/launcher" android:label="@string/app_name" 
android:debuggable="true" android:name=".GlobalStateData">

Answer 4

好的，你做错了，

创建类似于

的应用程序类

class MyApp extends Application {

 private String myState;

 public String getState(){
 return myState;
 }
 public void setState(String s){
 myState = s;
 }
}

在活动中获取您的Application类对象，

class Blah extends Activity {

@Override
public void onCreate(Bundle b){
...
MyApp appState = ((MyApp)getApplicationContext());
String state = appState.getState();
...
 }
}

在清单文件中声明您的Application类，如

<application android:icon="@drawable/icon" android:label="@string/app_name" android:name=".MyApp">

有关详情，请参阅本教程Android Application Class

Android应用程序中的类转换异常

4 个答案: