問題描述
android.webkit.WebView 無法轉換為 android.widget.Button (android.webkit.WebView cannot be cast to android.widget.Button)
I was working on a GUI inside of my app. I originally had a crappy look to it that just contained all of the basic stuff to test my java functions in. After I had all the functions up and running I redisgned the GUI using the graphical editor in Eclipse. The next time I ran my app I had the android.webkit.WebView cannot be cast to android.widget.Button in my LogCat. I didn't change anything in the java and all the declarations in the GUI are the same as far as I can tell. I can easily revert the GUI back to the crappy version but that doesn't help me much. I hope someone on here can help me find my problem. I have posted the xml, java, and 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;
}
}
}
參考解法
方法 1:
Perhaps the auto‑generated R class is messed up. Try to clean and rebuild your project by using Project > Clean... in Eclipse.
(by Sam Bevins、Ridcully)