我想存储一个时间值,需要检索和编辑它。我如何使用SharedPreferences来做到这一点?
当前回答
简单的方法:
保存:
getPreferences(MODE_PRIVATE).edit().putString("Name of variable",value).commit();
检索:
your_variable = getPreferences(MODE_PRIVATE).getString("Name of variable",default value);
其他回答
Edit
SharedPreferences pref = getSharedPreferences("YourPref", MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.putString("yourValue", value);
editor.commit();
Read
SharedPreferences pref = getSharedPreferences("YourPref", MODE_PRIVATE);
value= pref.getString("yourValue", "");
我创建了一个Helper类来简化我的生活。这是一个泛型类,有很多在应用程序中常用的方法,如共享首选项,电子邮件有效性,日期时间格式。在代码中复制这个类,并在任何需要的地方访问它的方法。
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.SharedPreferences;
import android.support.v4.app.FragmentActivity;
import android.view.inputmethod.InputMethodManager;
import android.widget.EditText;
import android.widget.Toast;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
/**
* Created by Zohaib Hassan on 3/4/2016.
*/
public class Helper {
private static ProgressDialog pd;
public static void saveData(String key, String value, Context context) {
SharedPreferences sp = context.getApplicationContext()
.getSharedPreferences("appData", 0);
SharedPreferences.Editor editor;
editor = sp.edit();
editor.putString(key, value);
editor.commit();
}
public static void deleteData(String key, Context context){
SharedPreferences sp = context.getApplicationContext()
.getSharedPreferences("appData", 0);
SharedPreferences.Editor editor;
editor = sp.edit();
editor.remove(key);
editor.commit();
}
public static String getSaveData(String key, Context context) {
SharedPreferences sp = context.getApplicationContext()
.getSharedPreferences("appData", 0);
String data = sp.getString(key, "");
return data;
}
public static long dateToUnix(String dt, String format) {
SimpleDateFormat formatter;
Date date = null;
long unixtime;
formatter = new SimpleDateFormat(format);
try {
date = formatter.parse(dt);
} catch (Exception ex) {
ex.printStackTrace();
}
unixtime = date.getTime();
return unixtime;
}
public static String getData(long unixTime, String formate) {
long unixSeconds = unixTime;
Date date = new Date(unixSeconds);
SimpleDateFormat sdf = new SimpleDateFormat(formate);
String formattedDate = sdf.format(date);
return formattedDate;
}
public static String getFormattedDate(String date, String currentFormat,
String desiredFormat) {
return getData(dateToUnix(date, currentFormat), desiredFormat);
}
public static double distance(double lat1, double lon1, double lat2,
double lon2, char unit) {
double theta = lon1 - lon2;
double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2))
+ Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2))
* Math.cos(deg2rad(theta));
dist = Math.acos(dist);
dist = rad2deg(dist);
dist = dist * 60 * 1.1515;
if (unit == 'K') {
dist = dist * 1.609344;
} else if (unit == 'N') {
dist = dist * 0.8684;
}
return (dist);
}
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
/* :: This function converts decimal degrees to radians : */
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
private static double deg2rad(double deg) {
return (deg * Math.PI / 180.0);
}
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
/* :: This function converts radians to decimal degrees : */
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
private static double rad2deg(double rad) {
return (rad * 180.0 / Math.PI);
}
public static int getRendNumber() {
Random r = new Random();
return r.nextInt(360);
}
public static void hideKeyboard(Context context, EditText editText) {
InputMethodManager imm = (InputMethodManager) context
.getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(editText.getWindowToken(), 0);
}
public static void showLoder(Context context, String message) {
pd = new ProgressDialog(context);
pd.setCancelable(false);
pd.setMessage(message);
pd.show();
}
public static void showLoderImage(Context context, String message) {
pd = new ProgressDialog(context);
pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
pd.setCancelable(false);
pd.setMessage(message);
pd.show();
}
public static void dismissLoder() {
pd.dismiss();
}
public static void toast(Context context, String text) {
Toast.makeText(context, text, Toast.LENGTH_LONG).show();
}
/*
public static Boolean connection(Context context) {
ConnectionDetector connection = new ConnectionDetector(context);
if (!connection.isConnectingToInternet()) {
Helper.showAlert(context, "No Internet access...!");
//Helper.toast(context, "No internet access..!");
return false;
} else
return true;
}*/
public static void removeMapFrgment(FragmentActivity fa, int id) {
android.support.v4.app.Fragment fragment;
android.support.v4.app.FragmentManager fm;
android.support.v4.app.FragmentTransaction ft;
fm = fa.getSupportFragmentManager();
fragment = fm.findFragmentById(id);
ft = fa.getSupportFragmentManager().beginTransaction();
ft.remove(fragment);
ft.commit();
}
public static AlertDialog showDialog(Context context, String message) {
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setMessage(message);
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int id) {
// TODO Auto-generated method stub
}
});
return builder.create();
}
public static void showAlert(Context context, String message) {
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setTitle("Alert");
builder.setMessage(message)
.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.dismiss();
}
}).show();
}
public static boolean isURL(String url) {
if (url == null)
return false;
boolean foundMatch = false;
try {
Pattern regex = Pattern
.compile(
"\\b(?:(https?|ftp|file)://|www\\.)?[-A-Z0-9+&#/%?=~_|$!:,.;]*[A-Z0-9+&@#/%=~_|$]\\.[-A-Z0-9+&@#/%?=~_|$!:,.;]*[A-Z0-9+&@#/%=~_|$]",
Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE);
Matcher regexMatcher = regex.matcher(url);
foundMatch = regexMatcher.matches();
return foundMatch;
} catch (PatternSyntaxException ex) {
// Syntax error in the regular expression
return false;
}
}
public static boolean atLeastOneChr(String string) {
if (string == null)
return false;
boolean foundMatch = false;
try {
Pattern regex = Pattern.compile("[a-zA-Z0-9]",
Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE);
Matcher regexMatcher = regex.matcher(string);
foundMatch = regexMatcher.matches();
return foundMatch;
} catch (PatternSyntaxException ex) {
// Syntax error in the regular expression
return false;
}
}
public static boolean isValidEmail(String email, Context context) {
String expression = "^[\\w\\.-]+@([\\w\\-]+\\.)+[A-Z]{2,4}$";
CharSequence inputStr = email;
Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(inputStr);
if (matcher.matches()) {
return true;
} else {
// Helper.toast(context, "Email is not valid..!");
return false;
}
}
public static boolean isValidUserName(String email, Context context) {
String expression = "^[0-9a-zA-Z]+$";
CharSequence inputStr = email;
Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(inputStr);
if (matcher.matches()) {
return true;
} else {
Helper.toast(context, "Username is not valid..!");
return false;
}
}
public static boolean isValidDateSlash(String inDate) {
SimpleDateFormat dateFormat = new SimpleDateFormat("dd/mm/yyyy");
dateFormat.setLenient(false);
try {
dateFormat.parse(inDate.trim());
} catch (ParseException pe) {
return false;
}
return true;
}
public static boolean isValidDateDash(String inDate) {
SimpleDateFormat dateFormat = new SimpleDateFormat("dd-mm-yyyy");
dateFormat.setLenient(false);
try {
dateFormat.parse(inDate.trim());
} catch (ParseException pe) {
return false;
}
return true;
}
public static boolean isValidDateDot(String inDate) {
SimpleDateFormat dateFormat = new SimpleDateFormat("dd.mm.yyyy");
dateFormat.setLenient(false);
try {
dateFormat.parse(inDate.trim());
} catch (ParseException pe) {
return false;
}
return true;
}
}
存储在SharedPreferences中
SharedPreferences preferences = getSharedPreferences("temp", getApplicationContext().MODE_PRIVATE);
Editor editor = preferences.edit();
editor.putString("name", name);
editor.commit();
获取SharedPreferences
SharedPreferences preferences=getSharedPreferences("temp", getApplicationContext().MODE_PRIVATE);
String name=preferences.getString("name",null);
注:“temp”为sharedpreferences名称,“name”为输入值。如果value不存在,则返回null
编辑sharedpreference中的数据
SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();
editor.putString("text", mSaved.getText().toString());
editor.putInt("selection-start", mSaved.getSelectionStart());
editor.putInt("selection-end", mSaved.getSelectionEnd());
editor.apply();
从sharedpreference中检索数据
SharedPreferences prefs = getPreferences(MODE_PRIVATE);
String restoredText = prefs.getString("text", null);
if (restoredText != null)
{
//mSaved.setText(restoredText, TextView.BufferType.EDITABLE);
int selectionStart = prefs.getInt("selection-start", -1);
int selectionEnd = prefs.getInt("selection-end", -1);
/*if (selectionStart != -1 && selectionEnd != -1)
{
mSaved.setSelection(selectionStart, selectionEnd);
}*/
}
Edit
我从API Demo样本中截取了这个片段。它有一个编辑文本框。在这种情况下,它不是必需的。我也有同样的看法。
您可以使用以下方法保存值:
public void savePreferencesForReasonCode(Context context,
String key, String value) {
SharedPreferences sharedPreferences = PreferenceManager
.getDefaultSharedPreferences(context);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString(key, value);
editor.commit();
}
使用这个方法,你可以从SharedPreferences中获取值:
public String getPreferences(Context context, String prefKey) {
SharedPreferences sharedPreferences = PreferenceManager
.getDefaultSharedPreferences(context);
return sharedPreferences.getString(prefKey, "");
}
这里prefKey是用来保存特定值的键。谢谢。
推荐文章
- 警告:API ' variable . getjavacompile()'已过时,已被' variable . getjavacompileprovider()'取代
- 安装APK时出现错误
- 碎片中的onCreateOptionsMenu
- TextView粗体通过XML文件?
- 如何使线性布局的孩子之间的空间?
- DSL元素android.dataBinding。enabled'已过时,已被'android.buildFeatures.dataBinding'取代
- ConstraintLayout:以编程方式更改约束
- PANIC: AVD系统路径损坏。检查ANDROID_SDK_ROOT值
- 如何生成字符串类型的buildConfigField
- Recyclerview不调用onCreateViewHolder
- Android API 21工具栏填充
- Android L中不支持操作栏导航模式
- 如何在TextView中添加一个子弹符号?
- PreferenceManager getDefaultSharedPreferences在Android Q中已弃用
- 在Android Studio中创建aar文件