android.webkit.WebView無法轉換爲android.widget.Button

Question

我正在使用我的應用程序內部的GUI。我最初看起來很蹩腳，只是包含了所有基本的東西來測試我的java函數。在我開始運行所有函數之後，我使用Eclipse中的圖形編輯器重新設置了GUI。下一次我運行我的應用程序時，我的android.webkit.WebView無法在我的LogCat中轉換爲android.widget.Button。據我所知，我沒有改變java中的任何內容，GUI中的所有聲明都是相同的。我可以輕鬆地將GUI恢復到糟糕的版本，但這對我沒有多大幫助。我希望這裏有人能幫我找到我的問題。我已經發布了xml，java和LogCat。

05-09 13:25:19.756: E/AndroidRuntime(10424): FATAL EXCEPTION: main 
05-09 13:25:19.756: E/AndroidRuntime(10424): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.dcc/com.example.dcc.ActionItem}: 
java.lang.ClassCastException: android.webkit.WebView cannot be cast to android.widget.Button 
05-09 13:25:19.756: E/AndroidRuntime(10424): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at android.app.ActivityThread.access$600(ActivityThread.java:130) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at android.os.Handler.dispatchMessage(Handler.java:99) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at android.os.Looper.loop(Looper.java:137) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at android.app.ActivityThread.main(ActivityThread.java:4745) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at java.lang.reflect.Method.invokeNative(Native Method) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at java.lang.reflect.Method.invoke(Method.java:511) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at dalvik.system.NativeStart.main(Native Method) 
05-09 13:25:19.756: E/AndroidRuntime(10424): Caused by: java.lang.ClassCastException: android.webkit.WebView cannot be cast to android.widget.Button 
05-09 13:25:19.756: E/AndroidRuntime(10424): at com.example.dcc.ActionItem.onCreate(ActionItem.java:54) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at android.app.Activity.performCreate(Activity.java:5008) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079) 
05-09 13:25:19.756: E/AndroidRuntime(10424): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023) 
05-09 13:25:19.756: E/AndroidRuntime(10424): ... 11 more 



<GridLayout 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" 
android:columnCount="4" > 
<LinearLayout 
    android:layout_width="212dp" 
    android:layout_height="match_parent" 
    android:layout_column="0" 
    android:layout_columnSpan="3" 
    android:layout_gravity="left" 
    android:layout_row="0" 
    android:orientation="vertical" > 

    <Button 
     android:id="@+id/button1" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:text="@string/Button1_name" 
     android:drawableRight="@drawable/news"/> 
    <Button 
     android:id="@+id/button2" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:text="@string/Button2_name" /> 
    <Button 
     android:id="@+id/button3" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:text="@string/Button3_name" 
     android:drawableRight="@drawable/cal"/> 
    <Button 
     android:id="@+id/button4" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:text="@string/Button4_name" 
     android:drawableRight="@drawable/mail"/> 
    <Button 
     android:id="@+id/button5" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:text="@string/Button5_name" 
     android:drawableRight="@drawable/gallery" /> 
    <Button 
     android:id="@+id/button6" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:text="@string/Button6_name" 
     android:drawableRight="@drawable/report" /> 
    <Button 
     android:id="@+id/button7" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:text="@string/Button7_name" 
     android:drawableRight="@drawable/ep" /> 
    <Button 
     android:id="@+id/button8" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:text="@string/Button8_name" 
     android:drawableRight="@drawable/directory" /> 
</LinearLayout> 
<GridLayout 
android:id="@+id/a" 
android:layout_width="wrap_content" 
android:layout_height="match_parent" 
android:layout_column="1" 
android:layout_columnSpan="2" 
android:layout_gravity="left" 
android:layout_row="0" 
android:columnCount="2" > 
</GridLayout> 
<ImageView 
android:id="@+id/imageView1" 
android:layout_width="10dp" 
android:layout_height="fill_parent" 
android:layout_column="2" 
android:layout_gravity="left" 
android:layout_row="0" 
android:background="@drawable/black" 
tools:ignore="ContentDescription" /> 

　 



<ScrollView 
    android:id="@+id/scrollView1" 
    android:layout_width="238dp" 
    android:layout_height="fill_parent" 
    android:layout_column="3" 
    android:layout_gravity="left|top" 
    android:layout_row="0" 
    android:background="@android:color/black" > 

    <LinearLayout 
     android:layout_width="fill_parent" 
     android:layout_height="match_parent" 
     android:orientation="vertical" > 

     <TextView 
      android:id="@+id/feedtitle" 
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content" /> 

     <TextView 
      android:id="@+id/feeddescribtion" 
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content" /> 

     <TextView 
      android:id="@+id/feedpubdate" 
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content" /> 

     <TextView 
      android:id="@+id/feedlink" 
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content" 
      android:autoLink="web" /> 

     <ListView 
      android:id="@android:id/list" 
      android:layout_width="fill_parent" 
      android:layout_height="594dp" > 
     </ListView> 

     <TextView 
      android:id="@android:id/empty" 
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content" 
      android:text="waiting" /> 
    </LinearLayout> 
</ScrollView> 

<WebView 
    android:id="@+id/webView1" 
    android:layout_width="830dp" 
    android:layout_height="555dp" 
    android:layout_column="3" 
    android:layout_gravity="right|bottom" 
    android:layout_row="0" /> 

<Button 
    android:id="@+id/email_button1" 
    android:layout_width="585dp" 
    android:layout_height="114dp" 
    android:layout_column="3" 
    android:layout_gravity="center_horizontal|top" 
    android:layout_row="0" 
    android:text="Submit Action Item Now" /> 

<TextView 
    android:id="@+id/actionView" 
    android:layout_width="243dp" 
    android:layout_height="113dp" 
    android:layout_column="3" 
    android:layout_gravity="right|top" 
    android:layout_row="0" 
    android:text="Loading" /> 


</GridLayout> 





package com.example.dcc; 

import java.io.IOException; 
import java.net.MalformedURLException; 
import java.net.URL; 

import javax.xml.parsers.ParserConfigurationException; 
import javax.xml.parsers.SAXParser; 
import javax.xml.parsers.SAXParserFactory; 

import org.xml.sax.InputSource; 
import org.xml.sax.SAXException; 
import org.xml.sax.XMLReader; 

import android.app.ListActivity; 
import android.content.Intent; 
import android.net.Uri; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.webkit.WebSettings; 
import android.webkit.WebView; 
import android.webkit.WebViewClient; 
import android.widget.ArrayAdapter; 
import android.widget.Button; 
import android.widget.ListView; 
import android.widget.TextView; 

public class ActionItem extends ListActivity implements OnClickListener { 
    // Create buttons Globally so they are available to all methods 
    public static RSSFeed myRssFeed = null; 
    private Button btnEmail = null; 
    static WebView webView; 
    Button newsB; 
    Button loginB; 
    Button calB; 
    Button mailB; 
    Button photoB; 
    Button reportB; 
    Button actionB; 
    Button directoryB; 

    String currentItem; 
    TextView thisAction; 
    int currentLocation; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.action_item); 

     btnEmail = (Button) findViewById(R.id.email_button1); 
     newsB = (Button) findViewById(R.id.button1); 
     loginB = (Button) findViewById(R.id.button2); 
     calB = (Button) findViewById(R.id.button3); 
     mailB = (Button) findViewById(R.id.button4); 
     photoB = (Button) findViewById(R.id.button5); 
     reportB = (Button) findViewById(R.id.button6); 
     actionB = (Button) findViewById(R.id.button7); 
     directoryB = (Button) findViewById(R.id.button8); 
     thisAction = (TextView) findViewById(R.id.actionView); 

     newsB.setOnClickListener(this); 
     loginB.setOnClickListener(this); 
     calB.setOnClickListener(this); 
     mailB.setOnClickListener(this); 
     photoB.setOnClickListener(this); 
     reportB.setOnClickListener(this); 
     actionB.setOnClickListener(this); 
     directoryB.setOnClickListener(this); 
     btnEmail.setOnClickListener(this); 

     new MyTask().execute(); 

     // this portion of the onCreate is dedicated to running the webView 
     // another webpage: http://creflodollarministries.org/ 
     // main webpage: http://www.virtualDiscoveryCenter.net 
     webView = (WebView) findViewById(R.id.webView1); 
     webView.setWebViewClient(new WebViewClient()); 
     webView.loadUrl("http://www.virtualDiscoveryCenter.net"); 
     WebSettings webSettings = webView.getSettings(); 
     webSettings.setJavaScriptEnabled(true); 

     Uri data = getIntent().getData(); 

     if (savedInstanceState == null) { 
      String url = getIntent().getDataString(); 
      // do something with this URL. 
      webView.loadUrl(url); 
     } 

    } 

    private class MyTask extends AsyncTask<Void, Void, Void> { 

     @Override 
     protected Void doInBackground(Void... arg0) { 
      try { 
       URL rssUrl = new URL(
         "http://www.virtualdiscoverycenter.net/feed/");// http://www.virtualdiscoverycenter.net/feed/ 
       SAXParserFactory mySAXParserFactory = SAXParserFactory 
         .newInstance(); 
       SAXParser mySAXParser = mySAXParserFactory.newSAXParser(); 
       XMLReader myXMLReader = mySAXParser.getXMLReader(); 
       RSSHandler myRSSHandler = new RSSHandler(); 
       myXMLReader.setContentHandler(myRSSHandler); 
       InputSource myInputSource = new InputSource(rssUrl.openStream()); 
       myXMLReader.parse(myInputSource); 

       myRssFeed = myRSSHandler.getFeed(); 
      } catch (MalformedURLException e) { 
       e.printStackTrace(); 
      } catch (ParserConfigurationException e) { 
       e.printStackTrace(); 
      } catch (SAXException e) { 
       e.printStackTrace(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 

      return null; 
     } 

     @Override 
     protected void onPostExecute(Void result) { 
      if (myRssFeed != null) { 
       TextView feedTitle = (TextView) findViewById(R.id.feedtitle); 
       TextView feedDescribtion = (TextView) findViewById(R.id.feeddescribtion); 
       TextView feedPubdate = (TextView) findViewById(R.id.feedpubdate); 
       TextView feedLink = (TextView) findViewById(R.id.feedlink); 
       feedTitle.setText(myRssFeed.getTitle()); 
       feedDescribtion.setText(myRssFeed.getDescription()); 
       feedPubdate.setText(myRssFeed.getPubdate()); 
       feedLink.setText(myRssFeed.getLink()); 

       ArrayAdapter<RSSItem> adapter = new ArrayAdapter<RSSItem>(
         getApplicationContext(), 
         android.R.layout.simple_list_item_1, 
         myRssFeed.getList()); 
       setListAdapter(adapter); 

       thisAction.setText(myRssFeed.getItem(0).getTitle()); 

      } else { 

       TextView textEmpty = (TextView) findViewById(android.R.id.empty); 
       textEmpty.setText("No Feed Found!"); 
      } 

      super.onPostExecute(result); 
     } 

    } 

    @Override 
    protected void onListItemClick(ListView l, View v, int position, long id) { 

     // Uri feedUri = Uri.parse(myRssFeed.getItem(position).getLink()); 
     // Intent myIntent = new Intent(Intent.ACTION_VIEW, feedUri); 
     // startActivity(myIntent); 
     String url = myRssFeed.getItem(position).getLink(); 
     currentItem = myRssFeed.getItem(position).getTitle(); 
     currentLocation = position; 
     thisAction.setText(currentItem); 
     webView.loadUrl(url); 
    } 

    public void sendEmail(View v) { 
     // The following code is the implementation of Email client 
     Intent i = new Intent(android.content.Intent.ACTION_SEND); 
     i.setType("text/plain"); 
     String[] address = { "bevins2012@hotmail.com" }; 

     i.putExtra(android.content.Intent.EXTRA_EMAIL, address); 
     i.putExtra(android.content.Intent.EXTRA_SUBJECT, myRssFeed.getItem(currentLocation).getDescription()); 
     i.putExtra(android.content.Intent.EXTRA_TEXT, 
       "Action Item from DCC app."); 
     startActivityForResult((Intent.createChooser(i, "Email")), 1); 
    } 

    public void onClick(View v) { 
     // this switch listens for any and all click actions in the app 
     // each case is a button in the menu. 
     switch (v.getId()) { 
     case R.id.button1: 
      startActivity(new Intent(this, AndroidRssReader.class)); 
      break; 
     case R.id.button2: 
      startActivity(new Intent(this, MainActivity.class)); 
      break; 
     case R.id.button3: 
      startActivity(new Intent(this, MainActivity.class)); 
      break; 
     case R.id.button4: 
      startActivity(new Intent(this, EmailMain.class)); 
      break; 
     case R.id.button5: 
      startActivity(new Intent(this, CustomizedListView.class)); 
      break; 
     case R.id.button6: 
      startActivity(new Intent(this, LaunchActivity.class)); 
      break; 
     case R.id.button7: 
      startActivity(new Intent(this, ActionItem.class)); 
      break; 
     case R.id.button8: 
      startActivity(new Intent(this, MainActivity.class)); 
      finish(); 
      break; 
     case R.id.email_button1: 
      // Calling sendEmail from the activity class 
      sendEmail(v); 
      break; 
     } 
    } 
} 

Answer 1

也許自動生成的R類被搞亂了。嘗試在Eclipse中使用Project> Clean ...清理和重建項目。