Question

如何在更改语言（列表首选项）时更改应用程序区域设置？

我在Android Studio中使用了自动生成的SettingsActivity，当lang_list的listpreference改变时，我想使用所选语言环境中的资源（字符串）。我从Function to manage resources on the basis of locale得到了参考。在setLocale（）方法中调用getResources（），它给出了错误：java.lang.NullPointerException：尝试在空对象引用上调用虚方法'android.content.res.Resources android.content.Context.getResources（）'。我在这里粘贴了我的SettingsActivity

package org.nrum.nrum;

import android.annotation.TargetApi;
import android.content.Context;
import android.content.Intent;
import android.content.res.Configuration;
import android.content.res.Resources;

import android.media.Ringtone;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.preference.ListPreference;
import android.preference.Preference;
import android.preference.PreferenceFragment;
import android.preference.PreferenceManager;

import android.preference.RingtonePreference;
import android.support.v4.app.NavUtils;
import android.support.v7.app.ActionBar;
import android.text.TextUtils;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MenuItem;
import java.util.List;
import java.util.Locale;
public class SettingsActivity extends AppCompatPreferenceActivity {


 private static Preference.OnPreferenceChangeListener sBindPreferenceSummaryToValueListener = new Preference.OnPreferenceChangeListener() {

        @Override
        public boolean onPreferenceChange(Preference preference, Object value) {
            String stringValue = value.toString();
        if (preference instanceof ListPreference) {
            // For list preferences, look up the correct display value in
            // the preference's 'entries' list.
            ListPreference listPreference = (ListPreference) preference;
            int index = listPreference.findIndexOfValue(stringValue);

            // Set the summary to reflect the new value.
            preference.setSummary(
                    index >= 0
                            ? listPreference.getEntries()[index]
                            : null);

        } else if (preference instanceof RingtonePreference) {
            // For ringtone preferences, look up the correct display value
            // using RingtoneManager.
            if (TextUtils.isEmpty(stringValue)) {
                // Empty values correspond to 'silent' (no ringtone).
                preference.setSummary(R.string.pref_ringtone_silent);

            } else {
                Ringtone ringtone = RingtoneManager.getRingtone(
                        preference.getContext(), Uri.parse(stringValue));

                if (ringtone == null) {
                    // Clear the summary if there was a lookup error.
                    preference.setSummary(null);
                } else {
                    // Set the summary to reflect the new ringtone display
                    // name.
                    String name = ringtone.getTitle(preference.getContext());
                    preference.setSummary(name);
                }
            }

        } else {
            // For all other preferences, set the summary to the value's
            // simple string representation.
            preference.setSummary(stringValue);
        }
        return true;
    }
};

/**
 * Helper method to determine if the device has an extra-large screen. For
 * example, 10" tablets are extra-large.
 */
private static boolean isXLargeTablet(Context context) {
    return (context.getResources().getConfiguration().screenLayout
            & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_XLARGE;
}

/**
 * Binds a preference's summary to its value. More specifically, when the
 * preference's value is changed, its summary (line of text below the
 * preference title) is updated to reflect the value. The summary is also
 * immediately updated upon calling this method. The exact display format is
 * dependent on the type of preference.
 *
 * @see #sBindPreferenceSummaryToValueListener
 */
private static void bindPreferenceSummaryToValue(Preference preference) {
    // Set the listener to watch for value changes.
    preference.setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener);
    String mKey = preference.getKey();
    String mValue = PreferenceManager.getDefaultSharedPreferences(preference.getContext()).getString(preference.getKey(), "");
    if(mKey.equals("lang_list")) {
        Log.d("mKey",mKey);
        if(mValue.equals("3")) {
            //ne locale
            new SettingsActivity().setLocale("ne");

        } else if (mValue.equals("2")) {
            //ra locale
            new SettingsActivity().setLocale("ra");

        } else {
            // en locale
            new SettingsActivity().setLocale("en");
        }
    }

    // Trigger the listener immediately with the preference's
    // current value.
    sBindPreferenceSummaryToValueListener.onPreferenceChange(preference,
            PreferenceManager
                    .getDefaultSharedPreferences(preference.getContext())
                    .getString(preference.getKey(), ""));
}


// method to set locale on the basis of selected app language
public void setLocale(String lang) {
    Locale myLocale = new Locale(lang);
    Resources res = getResources();
    DisplayMetrics dm = res.getDisplayMetrics();
    Configuration conf = res.getConfiguration();
    conf.locale = myLocale;
    res.updateConfiguration(conf, dm);
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setupActionBar();

}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        // Respond to the action bar's Up/Home button
        case android.R.id.home:
            super.onBackPressed();
            return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * Set up the {@link android.app.ActionBar}, if the API is available.
 */
private void setupActionBar() {
    ActionBar actionBar = getSupportActionBar();
    if (actionBar != null) {
        // Show the Up button in the action bar.
        actionBar.setDisplayHomeAsUpEnabled(true);
    }
}

@Override
public boolean onMenuItemSelected(int featureId, MenuItem item) {
    int id = item.getItemId();
    if (id == android.R.id.home) {
        if (!super.onMenuItemSelected(featureId, item)) {
            NavUtils.navigateUpFromSameTask(this);
        }
        return true;
    }
    return super.onMenuItemSelected(featureId, item);
}

/**
 * {@inheritDoc}
 */
@Override
public boolean onIsMultiPane() {
    return isXLargeTablet(this);
}

/**
 * {@inheritDoc}
 */
@Override
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public void onBuildHeaders(List<Header> target) {
    loadHeadersFromResource(R.xml.pref_headers, target);
}

/**
 * This method stops fragment injection in malicious applications.
 * Make sure to deny any unknown fragments here.
 */
protected boolean isValidFragment(String fragmentName) {
    return PreferenceFragment.class.getName().equals(fragmentName)
            || GeneralPreferenceFragment.class.getName().equals(fragmentName)
            || DataSyncPreferenceFragment.class.getName().equals(fragmentName)
            || NotificationPreferenceFragment.class.getName().equals(fragmentName);
}

/**
 * This fragment shows general preferences only. It is used when the
 * activity is showing a two-pane settings UI.
 */
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public static class GeneralPreferenceFragment extends PreferenceFragment {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.pref_general);
        setHasOptionsMenu(true);

        // Bind the summaries of EditText/List/Dialog/Ringtone preferences
        // to their values. When their values change, their summaries are
        // updated to reflect the new value, per the Android Design
        // guidelines.
        bindPreferenceSummaryToValue(findPreference("lang_list"));
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == android.R.id.home) {
            startActivity(new Intent(getActivity(), MainActivity.class));
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

/**
 * This fragment shows notification preferences only. It is used when the
 * activity is showing a two-pane settings UI.
 */
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public static class NotificationPreferenceFragment extends PreferenceFragment {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.pref_notification);
        setHasOptionsMenu(true);

        // Bind the summaries of EditText/List/Dialog/Ringtone preferences
        // to their values. When their values change, their summaries are
        // updated to reflect the new value, per the Android Design
        // guidelines.
        bindPreferenceSummaryToValue(findPreference("notifications_new_message_ringtone"));
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == android.R.id.home) {
            startActivity(new Intent(getActivity(), SettingsActivity.class));
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

/**
 * This fragment shows data and sync preferences only. It is used when the
 * activity is showing a two-pane settings UI.
 */
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public static class DataSyncPreferenceFragment extends PreferenceFragment {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.pref_data_sync);
        setHasOptionsMenu(true);

        // Bind the summaries of EditText/List/Dialog/Ringtone preferences
        // to their values. When their values change, their summaries are
        // updated to reflect the new value, per the Android Design
        // guidelines.
        bindPreferenceSummaryToValue(findPreference("sync_frequency"));
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == android.R.id.home) {
            startActivity(new Intent(getActivity(), SettingsActivity.class));
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

}

我已实现逻辑的代码块

private static void bindPreferenceSummaryToValue(Preference preference) {
    // Set the listener to watch for value changes.
    preference.setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener);
    String mKey = preference.getKey();
    String mValue = PreferenceManager.getDefaultSharedPreferences(preference.getContext()).getString(preference.getKey(), "");
    if(mKey.equals("lang_list")) {
        Log.d("mKey",mKey);
        if(mValue.equals("3")) {
            //ne locale
            new SettingsActivity().setLocale("ne");

        } else if (mValue.equals("2")) {
            //ra locale
            new SettingsActivity().setLocale("ra");

        } else {
            // en locale
            new SettingsActivity().setLocale("en");
        }
    }

    // Trigger the listener immediately with the preference's
    // current value.
    sBindPreferenceSummaryToValueListener.onPreferenceChange(preference,
            PreferenceManager
                    .getDefaultSharedPreferences(preference.getContext())
                    .getString(preference.getKey(), ""));
}

Answer 1

最终我在AppController中使用以下代码

@Override
public void onConfigurationChanged(Configuration newConfig)
{
    super.onConfigurationChanged(newConfig);
    if (locale != null)
    {
        newConfig.locale = locale;
        Locale.setDefault(locale);
        getBaseContext().getResources().updateConfiguration(newConfig, getBaseContext().getResources().getDisplayMetrics());
    }
}
@Override
public void onCreate() {
    super.onCreate();
    // for Active Android
    ActiveAndroid.initialize(this);
    mInstance = this;

    /*locale management*/
    SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
    Configuration config = getBaseContext().getResources().getConfiguration();
    String currentLangID = sharedPreferences.getString("lang_list", "");
    if(currentLangID.equals("3")) {
        //ne locale
        lang = "ne";

    } else if (currentLangID.equals("2")) {
        //ra locale
        lang = "ra";
    } else {
        // en locale
        lang = "en";
    }
    if (! "".equals(lang) && ! config.locale.getLanguage().equals(lang))
    {
        locale = new Locale(lang);
        Locale.setDefault(locale);
        config.locale = locale;
        getBaseContext().getResources().updateConfiguration(config, getBaseContext().getResources().getDisplayMetrics());
    }
}

AndroidManifest.xml内部

<application
    android:name="org.nrum.app.AppController"

在我添加的每个活动中

android:configChanges="layoutDirection|locale"

如何在更改语言（listPreferance）时更改我的应用语言环境？

1 个答案: