Java Android:如何从preference activity类调用main类的方法?
我有一个带有Java Android:如何从preference activity类调用main类的方法?,java,android,android-intent,listener,Java,Android,Android Intent,Listener,我有一个带有TextView的主活动类和一个设置活动(由Android的Studio模板生成) 在设置活动中,我声明了许多设置。主活动上的TextView显示其中一个设置,该设置由一个函数完成,该函数加载所有首选项的当前状态并将其保存在变量中 如果我在“设置”活动中更改了某些内容,侦听器将执行,但该值不会在主活动中更新 我不能使用onResume()方法,因为它也是在应用程序第一次启动时执行的 我尝试发送一个Intent并从监听器启动main类,但是这会创建一个main类的新实例,并且只允许您更
TextView
的主活动类和一个设置活动(由Android的Studio模板生成)
在设置活动中,我声明了许多设置。主活动上的TextView
显示其中一个设置,该设置由一个函数完成,该函数加载所有首选项的当前状态并将其保存在变量中
如果我在“设置”活动中更改了某些内容,侦听器将执行,但该值不会在主活动中更新
我不能使用onResume()
方法,因为它也是在应用程序第一次启动时执行的
我尝试发送一个Intent并从监听器启动main类,但是这会创建一个main类的新实例,并且只允许您更改一个首选项,因为监听器会触发
我的主要活动如下:
public class MainActivity extends ActionBarActivity {
private SharedPreferences prefs;
private double _lat;
public void loadPrefs(){
prefs = PreferenceManager.getDefaultSharedPreferences(this);
_lat = Double.parseDouble(prefs.getString("lat", ""));
//updates the iu
TextView helloThere = (TextView) findViewById(R.id.TextView_hello_world);
helloThere.setText(Double.toString(_lat));
}
@Override
protected void onResume() {
super.onResume();
String changes = getIntent().getStringExtra("prefChanged");
if(changes != null)
Log.d("DEBUG!!!!", changes);
else
Log.d("DEBUG!!!!", "No changes!!!!");
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
loadPrefs();
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (id == R.id.action_settings) {
// Launch Settings activity
Intent intent = new Intent(this, SettingsActivity.class);
startActivity(intent);
return true;
}
return super.onOptionsItemSelected(item);
}
}
这是设置活动(查看名为onSharedPreferenceChanged
)的函数):
公共类设置活动扩展首选项活动实现SharedReferences.OnSharedPreferenceChangeListener{
SharedReferences.OnSharedPreferenceChangeListener侦听器;
/**
*确定是否始终显示简化设置UI,其中
*设置显示在单个列表中。如果为false,则显示设置
*作为平板电脑上的主/详细双窗格视图。如果为true,则为单个窗格
*在平板电脑上显示。
*/
私有静态最终布尔值始终\u SIMPLE\u PREFS=false;
私人共享参考优先权;
@凌驾
已更改共享首选项上的公共void(SharedReferences SharedReferences,字符串键){
Log.d(“DEBUG!!”,“LISTENER!!”;
意图i=新意图(此,MainActivity.class);
i、 putExtra(“prechanged”,“Something changed…”);
星触觉(i);
}
@凌驾
受保护的void onResume(){
super.onResume();
prefs.RegisterOnSharedReferenceChangeListener(此);
}
@凌驾
受保护的void onPause(){
super.onPause();
prefs.UnregisteredPreferenceChangeListener(此);
}
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
prefs=PreferenceManager.getDefaultSharedPreferences(此);
}
@凌驾
后期创建时受保护的空(捆绑包savedInstanceState){
super.onPostCreate(savedInstanceState);
setupSimplePreferenceScreen();
}
/**
*如果设备配置为
*设备配置规定应使用简化的单窗格UI
*显示。
*/
私有void setupSimplePreferenceScreen(){
如果(!isSimplePreferences(此)){
返回;
}
//在简化的UI中,根本不使用片段,而是使用
//使用旧的PreferenceActivityAPI。
//添加“常规”首选项。
addPreferencesFromResource(R.xml.pref_-general);
//添加“通知”首选项和相应的标题。
PreferenceCategory fakeHeader=新的PreferenceCategory(此);
setTitle(R.string.pref_header_通知);
getPreferenceScreen().addPreference(fakeHeader);
addPreferencesFromResource(R.xml.pref_通知);
//添加“数据和同步”首选项以及相应的标题。
//fakeHeader=新的首选项类别(此);
//setTitle(R.string.pref_header_data_sync);
//getPreferenceScreen().addPreference(fakeHeader);
//addPreferencesFromResource(R.xml.pref_data_sync);
//将EditText/List/Dialog/Ringtone首选项的摘要绑定到
//它们的值。当它们的值发生变化时,它们的摘要会更新
//为了反映新的价值,根据Android设计指南。
//bindPreferenceSummaryToValue(FindReference(“示例文本”);
//bindPreferenceSummaryToValue(FindReference(“示例列表”);
bindPreferenceSummaryToValue(FindReference(“通知铃声”);
//bindPreferenceSummaryToValue(FindReference(“同步频率”);
}
/**
*{@inheritardoc}
*/
@凌驾
公共布尔值onIsMultiPane(){
返回isxlargetable(此)和&!isSimplePreferences(此);
}
/**
*确定设备是否有超大屏幕的帮助器方法。对于
*例如,10英寸的平板电脑是特大型的。
*/
私有静态布尔值isxlargetable(上下文){
返回(context.getResources().getConfiguration().screenLayout
&Configuration.SCREENLAYOUT\u SIZE\u MASK)>=Configuration.SCREENLAYOUT\u SIZE\u XLARGE;
}
/**
*确定是否应显示简化设置UI。这是
*如果通过{@link#ALWAYS _SIMPLE _PREFS}或设备强制执行,则为true
*没有更新的API,如{@link PreferenceFragment},或设备
*没有超大屏幕。在这种情况下,只有一个窗格
*应显示“简化”设置界面。
*/
私有静态布尔值首选项(上下文){
始终返回\u简单\u首选项
||Build.VERSION.SDK_INTpublic class SettingsActivity extends PreferenceActivity implements SharedPreferences.OnSharedPreferenceChangeListener {
SharedPreferences.OnSharedPreferenceChangeListener listener;
/**
* Determines whether to always show the simplified settings UI, where
* settings are presented in a single list. When false, settings are shown
* as a master/detail two-pane view on tablets. When true, a single pane is
* shown on tablets.
*/
private static final boolean ALWAYS_SIMPLE_PREFS = false;
private SharedPreferences prefs;
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
Log.d("DEBUG!!","LISTENER!!");
Intent i = new Intent(this, MainActivity.class);
i.putExtra("prefChanged","Something changed...");
startActivity(i);
}
@Override
protected void onResume() {
super.onResume();
prefs.registerOnSharedPreferenceChangeListener(this);
}
@Override
protected void onPause() {
super.onPause();
prefs.unregisterOnSharedPreferenceChangeListener(this);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
prefs = PreferenceManager.getDefaultSharedPreferences(this);
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
setupSimplePreferencesScreen();
}
/**
* Shows the simplified settings UI if the device configuration if the
* device configuration dictates that a simplified, single-pane UI should be
* shown.
*/
private void setupSimplePreferencesScreen() {
if (!isSimplePreferences(this)) {
return;
}
// In the simplified UI, fragments are not used at all and we instead
// use the older PreferenceActivity APIs.
// Add 'general' preferences.
addPreferencesFromResource(R.xml.pref_general);
// Add 'notifications' preferences, and a corresponding header.
PreferenceCategory fakeHeader = new PreferenceCategory(this);
fakeHeader.setTitle(R.string.pref_header_notifications);
getPreferenceScreen().addPreference(fakeHeader);
addPreferencesFromResource(R.xml.pref_notification);
// Add 'data and sync' preferences, and a corresponding header.
//fakeHeader = new PreferenceCategory(this);
//fakeHeader.setTitle(R.string.pref_header_data_sync);
//getPreferenceScreen().addPreference(fakeHeader);
//addPreferencesFromResource(R.xml.pref_data_sync);
// 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("example_text"));
//bindPreferenceSummaryToValue(findPreference("example_list"));
bindPreferenceSummaryToValue(findPreference("notifications_ringtone"));
//bindPreferenceSummaryToValue(findPreference("sync_frequency"));
}
/**
* {@inheritDoc}
*/
@Override
public boolean onIsMultiPane() {
return isXLargeTablet(this) && !isSimplePreferences(this);
}
/**
* 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;
}
/**
* Determines whether the simplified settings UI should be shown. This is
* true if this is forced via {@link #ALWAYS_SIMPLE_PREFS}, or the device
* doesn't have newer APIs like {@link PreferenceFragment}, or the device
* doesn't have an extra-large screen. In these cases, a single-pane
* "simplified" settings UI should be shown.
*/
private static boolean isSimplePreferences(Context context) {
return ALWAYS_SIMPLE_PREFS
|| Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB
|| !isXLargeTablet(context);
}
/**
* {@inheritDoc}
*/
@Override
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public void onBuildHeaders(List<Header> target) {
if (!isSimplePreferences(this)) {
loadHeadersFromResource(R.xml.pref_headers, target);
}
}
/**
* A preference value change listener that updates the preference's summary
* to reflect its new value.
*/
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;
}
};
/**
* 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);
// Trigger the listener immediately with the preference's
// current value.
sBindPreferenceSummaryToValueListener.onPreferenceChange(preference,
PreferenceManager
.getDefaultSharedPreferences(preference.getContext())
.getString(preference.getKey(), ""));
}
/**
* 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);
// 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("fixed_lat_long"));
bindPreferenceSummaryToValue(findPreference("example_text"));
bindPreferenceSummaryToValue(findPreference("example_list"));
}
}
/**
* 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);
// 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_ringtone"));
}
}