Android App crashes immediately when preferences screen is started

Question

I have been working on a preferences screen for an app, and I haven't even gotten it to display the screen before it crashes. I have examined several tutorials about shared preferences and my code resembles theirs, but nothing has worked. I think the problem is in my preferences.xml file, because I commented out everything except the opening of the XML file in my PreferenceActivity.

Here is my preferences.xml file:

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen
  xmlns:android="http://schemas.android.com/apk/res/android">
  <PreferenceCategory
    android:title="Password">
    <EditTextPreference
        android:name="Your Password"
        android:title="Password"
        android:defaultValue=""
        android:summary="For logging in if facial recognition fails"
        android:key="password" />
    <EditTextPreference
        android:name="Max Attempts"
        android:title="Max Attempts"
        android:defaultValue="3"
        android:summary="Max number of times to try authentication before falling back to password"
        android:key="maxAttempts" />
  </PreferenceCategory>
  <PreferenceCategory
    android:title="Security">
    <CheckBoxPreference
        android:title="Intruder Alert"
        android:defaultValue="false"
        android:summary="Notify me if you detect a face other than mine"
        android:key="intruderAlert" />
        </PreferenceCategory>
    <PreferenceCategory
        android:title="Intruder Notification">
        <EditTextPreference
        android:name="Your Email"
        android:title="email"
        android:defaultValue=""
        android:summary="An email address for us to notify"
        android:key="email" />
        <EditTextPreference
        android:name="Your Phone Number"
        android:title="phoneNumber"
        android:defaultValue=""
        android:summary="A phone number for us to notify"
        android:key="phoneNumber" />            
        </PreferenceCategory>
</PreferenceScreen>

And, in case I'm wrong and my problem is my java file, here's the PreferenceActivity. Most is commented out at the moment, but the program still crashes.

public class Preferences extends PreferenceActivity implements OnSharedPreferenceChangeListener {

    /*private EditTextPreference password;
    private EditTextPreference maxAttempts;
    private CheckBoxPreference intruderAlert;
    private EditTextPreference email;
    private EditTextPreference phoneNumber;

    String PassWord;
    int MaxAttempts;
    boolean IntruderAlert;
    String Email;
    String PhoneNumber;*/

    @Override
    public void onCreate(Bundle savedInstanceState) 
    {   
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.preferences);  
        //password = (EditTextPreference) getPreferenceScreen().findPreference("password");
        //maxAttempts = (EditTextPreference) getPreferenceScreen().findPreference("maxAttempts");
        //intruderAlert = (CheckBoxPreference) getPreferenceScreen().findPreference("intruderAlert");
        //email = (EditTextPreference) getPreferenceScreen().findPreference("email");
        //phoneNumber = (EditTextPreference) getPreferenceScreen().findPreference("phoneNumber");
    }

    private void setSummaries()
    {

    }

    @Override
    protected void onResume() 
    {
        /*super.onResume();
        String intruderAlertSetting;
        if (intruderAlert.isChecked())
            intruderAlertSetting = "on";
        else
            intruderAlertSetting = "off";
        password.setSummary("Your password is " +password.getText()+ ".");
        maxAttempts.setSummary("The max attempts that will be made is "+maxAttempts.getText() + ".");
        intruderAlert.setSummary("You have intruder alert set to" + intruderAlertSetting+".");
        if (email.getText().equals(""))
            email.setSummary("You have no email address stored.");
        else
            email.setSummary("Your stored email address is "+email.getText() + ".");
        if (phoneNumber.getText().equals(""))
            phoneNumber.setSummary("You have no phone number stored.");
        else
            phoneNumber.setSummary("Your stored phone number is " + phoneNumber.getText()+".");
        // Set up a listener whenever a key changes
        getPreferenceScreen().getSharedPreferences()
                .registerOnSharedPreferenceChangeListener(this);*/

    }

    @Override
    protected void onPause() 
    {
        /*super.onPause();

        String intruderAlertSetting;
        if (intruderAlert.isChecked())
            intruderAlertSetting = "on";
        else
            intruderAlertSetting = "off";
        password.setSummary("Your password is " +password.getText()+ ".");
        maxAttempts.setSummary("The max attempts that will be made is "+maxAttempts.getText() + ".");
        intruderAlert.setSummary("You have intruder alert set to" + intruderAlertSetting+".");
        if (email.getText().equals(""))
            email.setSummary("You have no email address stored.");
        else
            email.setSummary("Your stored email address is "+email.getText() + ".");
        if (phoneNumber.getText().equals(""))
            phoneNumber.setSummary("You have no phone number stored.");
        else
            phoneNumber.setSummary("Your stored phone number is " + phoneNumber.getText()+".");

        // Unregister the listener whenever a key changes
        getPreferenceScreen().getSharedPreferences()
                .unregisterOnSharedPreferenceChangeListener(this);*/
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences,String key) 
    {
        /*String intruderAlertSetting;
        if (intruderAlert.isChecked())
            intruderAlertSetting = "on";
        else
            intruderAlertSetting = "off";
        password.setSummary("Your password is " +password.getText()+ ".");
        maxAttempts.setSummary("The max attempts that will be made is "+maxAttempts.getText() + ".");
        intruderAlert.setSummary("You have intruder alert set to" + intruderAlertSetting+".");
        if (email.getText().equals(""))
            email.setSummary("You have no email address stored.");
        else
            email.setSummary("Your stored email address is "+email.getText() + ".");
        if (phoneNumber.getText().equals(""))
            phoneNumber.setSummary("You have no phone number stored.");
        else
            phoneNumber.setSummary("Your stored phone number is " + phoneNumber.getText()+".");
        PassWord = password.getText();
        MaxAttempts = Integer.parseInt(maxAttempts.getText());
        IntruderAlert = intruderAlert.isChecked();
        Email = email.getText();
        PhoneNumber = phoneNumber.getText();*/

    }   
}

Here is the LogCat info on the crash:

04-23 16:37:09.181: WARN/dalvikvm(818): threadid=1: thread exiting with uncaught exception (group=0x40015560)
04-23 16:37:09.221: ERROR/AndroidRuntime(818): FATAL EXCEPTION: main
04-23 16:37:09.221: ERROR/AndroidRuntime(818): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.cs.fsu.edu.project4/com.cs.fsu.edu.project4.Preferences}: android.view.InflateException: Binary XML file line #2: Error inflating class PreferenceScreen
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1622)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1638)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:928)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.os.Looper.loop(Looper.java:123)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.app.ActivityThread.main(ActivityThread.java:3647)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at java.lang.reflect.Method.invokeNative(Native Method)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at java.lang.reflect.Method.invoke(Method.java:507)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at dalvik.system.NativeStart.main(Native Method)
04-23 16:37:09.221: ERROR/AndroidRuntime(818): Caused by: android.view.InflateException: Binary XML file line #2: Error inflating class PreferenceScreen
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:581)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.view.LayoutInflater.inflate(LayoutInflater.java:386)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.view.LayoutInflater.inflate(LayoutInflater.java:320)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.view.LayoutInflater.inflate(LayoutInflater.java:276)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:207)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.app.Activity.setContentView(Activity.java:1657)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at com.cs.fsu.edu.project4.Preferences.onCreate(Preferences.java:33)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1586)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     ... 11 more
04-23 16:37:09.221: ERROR/AndroidRuntime(818): Caused by: java.lang.ClassNotFoundException: android.view.PreferenceScreen in loader dalvik.system.PathClassLoader[/data/app/com.cs.fsu.edu.project4-1.apk]
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:240)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at java.lang.ClassLoader.loadClass(ClassLoader.java:551)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.view.LayoutInflater.createView(LayoutInflater.java:471)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.view.LayoutInflater.onCreateView(LayoutInflater.java:549)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:66)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:568)
04-23 16:37:09.221: ERROR/AndroidRuntime(818):     ... 19 more
04-23 16:37:09.251: WARN/ActivityManager(62):   Force finishing activity com.cs.fsu.edu.project4/.Preferences

Answer 1

In your Preference Activity onCreate you probably had this:

setContentView(R.xml.prefs);

you need something like this instead:

addPreferencesFromResource(R.xml.prefs);

Refer to: PreferenceScreen class not found

Answer 2

也许您更改了首选项架构，请尝试删除存储在/ dbdata / databases / com_your_app / shared_prefs /或/ data / data / com_your_app中的旧偏好文件。

Answer 3

确保您具有AndroidManifest.xml文件中列出的活动

<activity android:name=".Preferences"></activity>

Answer 4

Somehow the app thinks PreferenceScreen is of package android.view , but the system docs only knows it in package android.preference

 Caused by: java.lang.ClassNotFoundException: android.view.PreferenceScreen in loader dalvik.system.PathClassLoader[/data/app/com.cs.fsu.edu.project4-1.apk]

Did you somehow add some class named PreferenceScreen in your app, which may confuse the system?

Answer 5

I'd like to add my cents here. My experience is, always make a clean build, always check your manifest for intents, activities, filters, permissions.

Check package names, sometimes you renamed packages which can go wrong.

Remove the previous app (created on differnt PC?) before installing, remove the old settings.

All this went wrong with me :-)

If this doesn't work, copy all files to a new project. Stupid, but this worked for me - uncommented everything, still didn't work. Then: ping, start & go.