问题
OK now I know that this question has been asked before several times on SO but none of the answers have worked for me.
I am attempting to create a custom preference for my project. More specifically it is a preference with a HorizontalListView attached directly underneath it. I basically created it by modifying this code for a SeekBarPreference (which I am also using and is working fine). My ListViewPreference is located in exactly the same folder as the SeelkBarPreference (which, as I said is having no problem) but I am constantly getting a ClassNotFoundException (see logcat below). Here is my ListViewPreference class:
package com.example.ebookreader;
import android.content.Context;
import android.content.res.TypedArray;
import android.preference.Preference;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.view.ViewParent;
import android.widget.RelativeLayout;
import android.widget.TextView;
public class ListViewPreference extends Preference {
private final String TAG = getClass().getName();
private static final String ROBOBUNNYNS = "http://robobunny.com";
private static final int DEFAULT_VALUE = 50;
private int mCurrentValue;
private String mUnitsLeft = "";
private String mUnitsRight = "";
private HorizontalListView mListView;
private TextView mStatusText;
public ListViewPreference(Context context, AttributeSet attrs) {
super(context, attrs);
initPreference(context, attrs);
}
public ListViewPreference(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initPreference(context, attrs);
}
private void initPreference(Context context, AttributeSet attrs) {
setValuesFromXml(attrs);
mListView = new HorizontalListView(context, attrs);
LayoutParams params = mListView.getLayoutParams();
params.width = LayoutParams.MATCH_PARENT;
params.height = LayoutParams.WRAP_CONTENT;
mListView.setLayoutParams(params);
}
private void setValuesFromXml(AttributeSet attrs) {
mUnitsLeft = getAttributeStringValue(attrs, ROBOBUNNYNS, "unitsLeft",
"");
String units = getAttributeStringValue(attrs, ROBOBUNNYNS, "units", "");
mUnitsRight = getAttributeStringValue(attrs, ROBOBUNNYNS, "unitsRight",
units);
}
private String getAttributeStringValue(AttributeSet attrs,
String namespace, String name, String defaultValue) {
String value = attrs.getAttributeValue(namespace, name);
if (value == null)
value = defaultValue;
return value;
}
@Override
protected View onCreateView(ViewGroup parent) {
RelativeLayout layout = null;
try {
LayoutInflater mInflater = (LayoutInflater) getContext()
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
layout = (RelativeLayout) mInflater.inflate(
R.layout.horizontal_list_view_preference, parent, false);
} catch (Exception e) {
Log.e(TAG, "Error creating seek bar preference", e);
}
return layout;
}
@Override
public void onBindView(View view) {
super.onBindView(view);
try {
// move our seekbar to the new view we've been given
ViewParent oldContainer = mListView.getParent();
ViewGroup newContainer = (ViewGroup) view
.findViewById(R.id.listViewPrefBarContainer);
if (oldContainer != newContainer) {
// remove the seekbar from the old view
if (oldContainer != null) {
((ViewGroup) oldContainer).removeView(mListView);
}
// remove the existing seekbar (there may not be one) and add
// ours
newContainer.removeAllViews();
newContainer.addView(mListView,
ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
}
} catch (Exception ex) {
Log.e(TAG, "Error binding view: " + ex.toString());
}
updateView(view);
}
/**
* Update a SeekBarPreference view with our current state
*
* @param view
*/
protected void updateView(View view) {
try {
RelativeLayout layout = (RelativeLayout) view;
mStatusText = (TextView) layout
.findViewById(R.id.listViewPrefValue);
mStatusText.setText(String.valueOf(mCurrentValue));
mStatusText.setMinimumWidth(30);
TextView unitsRight = (TextView) layout
.findViewById(R.id.listViewPrefUnitsRight);
unitsRight.setText(mUnitsRight);
TextView unitsLeft = (TextView) layout
.findViewById(R.id.listViewPrefUnitsLeft);
unitsLeft.setText(mUnitsLeft);
} catch (Exception e) {
Log.e(TAG, "Error updating seek bar preference", e);
}
}
@Override
protected Object onGetDefaultValue(TypedArray ta, int index) {
int defaultValue = ta.getInt(index, DEFAULT_VALUE);
return defaultValue;
}
@Override
protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
if (restoreValue) {
mCurrentValue = getPersistedInt(mCurrentValue);
} else {
int temp = 0;
try {
temp = (Integer) defaultValue;
} catch (Exception ex) {
Log.e(TAG, "Invalid default value: " + defaultValue.toString());
}
persistInt(temp);
mCurrentValue = temp;
}
}
}
For most people this problem is the result of not having a constructor with parameters Context and AttributeSet but as you can see, I clearly have it.
Here is the XML file where the error keeps on occurring:
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:custom="http://schemas.android.com/apk/res/com.example.ebookreader"
android:background="@drawable/wallpaper" >
<android:PreferenceCategory
android:key="device_settings"
android:title="Device Settings" >
<android:CheckBoxPreference
android:key="wifi"
android:summary="Enable or Disable Wi-Fi"
android:title="Wi-Fi" />
<android:CheckBoxPreference
android:key="bluetooth"
android:summary="Enable or Disable Bluetooth"
android:title="Bluetooth" />
<android:CheckBoxPreference
android:key="autosync"
android:summary="Enable or Disable AutoSync"
android:title="AutoSync" />
<custom:SeekBarPreference
android:id="@+id/brightness_adjust"
android:defaultValue="100"
android:key="brightness"
android:max="200"
android:summary="Adjust Brightness Levels"
android:title="Brightness" />
</android:PreferenceCategory>
<android:PreferenceCategory
android:key="account_settings"
android:title="Account Settings" >
<custom:ListViewPreference> <!-- Error happens here -->
android:id="@+id/font_selector"
android:key="font"
android:title="Font"
android:summary="Edit Font"
/>
</custom:ListViewPreference>
</android:PreferenceCategory>
</PreferenceScreen>
Below is my full Logcat:
03-14 17:53:14.290: E/AndroidRuntime(449): FATAL EXCEPTION: main
03-14 17:53:14.290: E/AndroidRuntime(449): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ebookreader/com.example.ebookreader.SettingsActivity}: android.view.InflateException: Binary XML file line #40: Error inflating class ListViewPreference
03-14 17:53:14.290: E/AndroidRuntime(449): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1736)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1752)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.app.ActivityThread.access$1500(ActivityThread.java:123)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:993)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.os.Handler.dispatchMessage(Handler.java:99)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.os.Looper.loop(Looper.java:126)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.app.ActivityThread.main(ActivityThread.java:3997)
03-14 17:53:14.290: E/AndroidRuntime(449): at java.lang.reflect.Method.invokeNative(Native Method)
03-14 17:53:14.290: E/AndroidRuntime(449): at java.lang.reflect.Method.invoke(Method.java:491)
03-14 17:53:14.290: E/AndroidRuntime(449): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
03-14 17:53:14.290: E/AndroidRuntime(449): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
03-14 17:53:14.290: E/AndroidRuntime(449): at dalvik.system.NativeStart.main(Native Method)
03-14 17:53:14.290: E/AndroidRuntime(449): Caused by: android.view.InflateException: Binary XML file line #40: Error inflating class ListViewPreference
03-14 17:53:14.290: E/AndroidRuntime(449): at android.preference.GenericInflater.createItemFromTag(GenericInflater.java:441)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.preference.GenericInflater.rInflate(GenericInflater.java:481)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.preference.GenericInflater.rInflate(GenericInflater.java:493)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.preference.GenericInflater.inflate(GenericInflater.java:326)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.preference.GenericInflater.inflate(GenericInflater.java:263)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.preference.PreferenceManager.inflateFromResource(PreferenceManager.java:269)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.preference.PreferenceActivity.addPreferencesFromResource(PreferenceActivity.java:1333)
03-14 17:53:14.290: E/AndroidRuntime(449): at com.example.ebookreader.SettingsActivity.onCreate(SettingsActivity.java:31)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1700)
03-14 17:53:14.290: E/AndroidRuntime(449): ... 11 more
03-14 17:53:14.290: E/AndroidRuntime(449): Caused by: java.lang.ClassNotFoundException: android.preference.ListViewPreference in loader dalvik.system.PathClassLoader[/data/app/com.example.ebookreader-2.apk]
03-14 17:53:14.290: E/AndroidRuntime(449): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:251)
03-14 17:53:14.290: E/AndroidRuntime(449): at java.lang.ClassLoader.loadClass(ClassLoader.java:548)
03-14 17:53:14.290: E/AndroidRuntime(449): at java.lang.ClassLoader.loadClass(ClassLoader.java:508)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.preference.GenericInflater.createItem(GenericInflater.java:375)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.preference.GenericInflater.onCreateItem(GenericInflater.java:417)
03-14 17:53:14.290: E/AndroidRuntime(449): at android.preference.GenericInflater.createItemFromTag(GenericInflater.java:428)
03-14 17:53:14.290: E/AndroidRuntime(449): ... 20 more
Any help would be greatly appreciated.
回答1:
but why you wrote
<custom:ListViewPreference
it should be
<com.example.ebookreader.ListViewPreference
As your package, where class placed, called
回答2:
Generally, you need to use the full path to a component:
<com.example.ebookreader.ListViewPreference
android:id="@+id/font_selector"
android:key="font"
android:title="Font"
android:summary="Edit Font"
/>
I have never seen the use of "Custom:" as an element.
来源：https://stackoverflow.com/questions/15417588/error-inflating-layout-with-java-lang-classnotfoundexception