Android ClassCastException - 清单问题

Question

尝试在我已经构建的应用程序中加入测验应用程序。我参加了测验的教程。当我运行我的应用程序并单击按钮启动测验时，我得到一个java.lang.ClassCastException: android.app.Application cannot be cast to com.example.myfirstllapp.quiz.ChuckApplication

我一直在研究，并且我的清单有问题。我似乎无法弄清楚。

下面是一个启动测验

package com.example.myfirstllapp; 

//import android.R; 
import java.io.IOException; 
import java.util.HashMap; 
import java.util.List; 

import com.example.myfirstllapp.quiz.ChuckApplication; 
import com.example.myfirstllapp.quiz.Constants; 
import com.example.myfirstllapp.quiz.DBHelper; 
import com.example.myfirstllapp.quiz.GamePlay; 
import com.example.myfirstllapp.quiz.Question; 
import com.example.myfirstllapp.quiz.QuestionActivity; 

import android.app.Activity; 
import android.content.Intent; 
import android.content.SharedPreferences; 
import android.database.SQLException; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.ImageView; 
import android.widget.Toast; 

public class Activia extends Activity implements OnClickListener { 

    private Button mButton; 
    private ImageView mImage; 
    private EditText mEditText; 
    private Button mChangeScreenButton; 
    private Button mWebButton; 
    private Button mPlayQuizButton; 

    private HashMap<String, Integer> mCharMap; 

    @Override 
    public void onCreate(Bundle bundle){ 
    super.onCreate(bundle); 
    initializeLayout(); 

    //hashmap can be used instead of if thens 
    populateHashMap(); 


    // Using HashMap might not need this yet 
    //mButton.setOnClickListener(this); 
    } 

    private void populateHashMap(){ 
     mCharMap = new HashMap<String, Integer>(); 
     mCharMap.put("bugsbunny", R.drawable.bugs); 
     mCharMap.put("clippy", R.drawable.clippy); 
     mCharMap.put("duder",R.drawable.duder); 
     mCharMap.put("cheesemouse",R.drawable.chuckecheese); 
    } 

    private void initializeLayout() { 
     setContentView(R.layout.ugly_layout); 
     mPlayQuizButton = (Button)findViewById(R.id.play_the_quiz); 
     mPlayQuizButton.setOnClickListener(this); 
     mButton = (Button)findViewById(R.id.button); 
     mImage = (ImageView)findViewById(R.id.image_view); 
     mEditText = (EditText)findViewById(R.id.edit_text); 
     mChangeScreenButton = (Button)findViewById(R.id.switch_screen_button); 
     mWebButton = (Button)findViewById(R.id.web_button); 
     //using hashmap call down here, I dont know why tho 
     mButton.setOnClickListener(this); 
     mChangeScreenButton.setOnClickListener(this); 
     mWebButton.setOnClickListener(this); 

    } 


    @Override 
    public void onClick(View v) { 
     switch(v.getId()){ 
     case R.id.button : 
      String enteredValue = mEditText.getText().toString(); 
      enteredValue = enteredValue.toLowerCase().replace(" ", ""); 

      if(enteredValue.length() == 0){ 
       Toast.makeText(this," You need to enter something",Toast.LENGTH_SHORT).show(); 
      } 

      Integer drawableId = mCharMap.get(enteredValue); 
      if(drawableId != null) { 
       mImage.setImageDrawable(getResources().getDrawable(drawableId)); 
      } 
      else{ 
       Toast.makeText(this,"Sorry The character you entered is not supported.",Toast.LENGTH_SHORT).show(); 
      } 
      mEditText.setText(""); 
      break; 
     case R.id.switch_screen_button : 
      Toast.makeText(this,"it clicks",Toast.LENGTH_SHORT).show(); 
      Intent intent = new Intent(this, CoolerActivity.class); 
      startActivity(intent); 
      break; 

     case R.id.web_button : 
      Toast.makeText(this,"it clicks",Toast.LENGTH_SHORT).show(); 
      Intent intent2 = new Intent(this, WebActivity.class); 
      startActivity(intent2); 
      break; 

     case R.id.play_the_quiz : 
      Toast.makeText(this,"It Clicks2",Toast.LENGTH_SHORT).show(); 

      //Get Question set // 
      List<Question> questions = getQuestionSetFromDb(); 

      //Initialise Game with retrieved question set /// 
      GamePlay c = new GamePlay(); 
      c.setQuestions(questions); 
      c.setNumRounds(getNumQuestions()); 
      ((ChuckApplication)getApplication()).setCurrentGame(c); 

      //Start Game Now.. // 
      Intent i = new Intent(this, QuestionActivity.class); 
      startActivityForResult(i, Constants.PLAYBUTTON); 


      break; 
     } 
    } 


    /** 
    * Method that retrieves a random set of questions from 
    * the database for the given difficulty 
    * @return 
    * @throws Error 
    */ 
    private List<Question> getQuestionSetFromDb() throws Error { 
     int diff = getDifficultySettings(); 
     int numQuestions = getNumQuestions(); 
     DBHelper myDbHelper = new DBHelper(this); 
     try { 
      myDbHelper.createDataBase(); 
     } catch (IOException ioe) { 
      throw new Error("Unable to create database"); 
     } 
     try { 
      myDbHelper.openDataBase(); 
     }catch(SQLException sqle){ 
      throw sqle; 
     } 
     List<Question> questions = myDbHelper.getQuestionSet(diff, numQuestions); 
     myDbHelper.close(); 
     return questions; 
    } 


    /** 
    * Method to return the difficulty settings 
    * @return 
    */ 
    private int getDifficultySettings() { 
     SharedPreferences settings = getSharedPreferences(Constants.SETTINGS, 0); 
     int diff = settings.getInt(Constants.DIFFICULTY, Constants.MEDIUM); 
     return diff; 
    } 

    /** 
    * Method to return the number of questions for the game 
    * @return 
    */ 
    private int getNumQuestions() { 
     SharedPreferences settings = getSharedPreferences(Constants.SETTINGS, 0); 
     int numRounds = settings.getInt(Constants.NUM_ROUNDS, 20); 
     return numRounds; 
    } 

，这里的活动代码是清单

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.example.myfirstllapp" 
    android:versionCode="1" 
    android:versionName="1.0" > 

    <uses-sdk 
     android:minSdkVersion="8" 
     android:targetSdkVersion="9" /> 
    <uses-permission android:name="android.permission.INTERNET" /> 


    <application 
     android:allowBackup="true" 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" 

     android:debuggable="true" > 
     <activity 
      android:name="com.example.myfirstllapp.Activia" 
      android:label="@string/app_name" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 
       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 

     <activity android:name=".CoolerActivity" /> 
     <activity android:name=".WebActivity" /> 

     <activity android:name="com.example.myfirstllapp.quiz.QuestionActivity" /> 
     <activity android:name="com.example.myfirstllapp.quiz.RulesActivity" /> 
     <activity android:name="com.example.myfirstllapp.quiz.EndgameActivity" /> 
     <activity android:name="com.example.myfirstllapp.quiz.SettingsActivity" /> 
     <activity android:name="com.example.myfirstllapp.quiz.AnswersActivity" /> 
     <activity android:name="com.example.myfirstllapp.quiz.ChuckApplication" /> 


    </application> 
    <application 
     android:name=".ChuckApplication" > 


     </application> 

</manifest> 

Answer 1

在应用元素的定义看看http://developer.android.com/guide/topics/manifest/application-element.html。 这些活动应该是应用程序的子代。