Set system date time and time zone

Setting the date, time and time zone of the system requires system permission and system signature. android:sharedUserId="android.uid.system"
You need to add the corresponding permissions in the manifest file

  <uses-permission android:name="android.permission.WRITE_SETTINGS"/>
  <uses-permission android:name="android.permission.WRITE_SECURE_SETTINGS"/>

• Determine whether the system uses the 24-hour system or the 12-hour system

  boolean is24Hour =  DateFormat.is24HourFormat(mContext);

• Set the hour system of the system

24 hour system

  android.provider.Settings.System.putString(mContext.getContentResolver(),
                android.provider.Settings.System.TIME_12_24, "24");

12 hour system

  android.provider.Settings.System.putString(mContext.getContentResolver(),
                android.provider.Settings.System.TIME_12_24, "12");

• Determine whether the time zone of the system is automatically obtained

  public boolean isTimeZoneAuto(){
    try {
        return  android.provider.Settings.Global.getInt(mContext.getContentResolver(),
                android.provider.Settings.Global.AUTO_TIME_ZONE) > 0;
    } catch (SettingNotFoundException e) {
        e.printStackTrace();
        return false;
    }
  }

• Set whether the time zone of the system is automatically obtained

  public void setAutoTimeZone(int checked){
    android.provider.Settings.Global.putInt(mContext.getContentResolver(),
            android.provider.Settings.Global.AUTO_TIME_ZONE, checked);
  }

• Determine whether the system time is automatically obtained

  public boolean isDateTimeAuto(){
    try {
        return android.provider.Settings.Global.getInt(mContext.getContentResolver(),
                android.provider.Settings.Global.AUTO_TIME) > 0;
    } catch (SettingNotFoundException e) {
        e.printStackTrace();
        return false;
    }
  }

• Set whether the time of the system needs to be acquired automatically

  public void setAutoDateTime(int checked){
    android.provider.Settings.Global.putInt(mContext.getContentResolver(),
            android.provider.Settings.Global.AUTO_TIME, checked);
  }

• Set system date

  Source code in reference system Settings

  public void setSysDate(int year,int month,int day){
    Calendar c = Calendar.getInstance();
    c.set(Calendar.YEAR, year);
    c.set(Calendar.MONTH, month);
    c.set(Calendar.DAY_OF_MONTH, day);
  
    long when = c.getTimeInMillis();
  
    if(when / 1000 < Integer.MAX_VALUE){
        ((AlarmManager)mContext.getSystemService(Context.ALARM_SERVICE)).setTime(when);
    }
  }

• Set system time

  Source code in reference system Settings

  public void setSysTime(int hour,int minute){
    Calendar c = Calendar.getInstance();
    c.set(Calendar.HOUR_OF_DAY, hour);
    c.set(Calendar.MINUTE, minute);
    c.set(Calendar.SECOND, 0);
    c.set(Calendar.MILLISECOND, 0);
  
    long when = c.getTimeInMillis();
  
    if(when / 1000 < Integer.MAX_VALUE){
        ((AlarmManager)mContext.getSystemService(Context.ALARM_SERVICE)).setTime(when);
    }
  }

• Set system time zone

  public void setTimeZone(String timeZone){
    final Calendar now = Calendar.getInstance();
    TimeZone tz = TimeZone.getTimeZone(timeZone);
    now.setTimeZone(tz);
  }

• Get the current time zone of the system

  public String getDefaultTimeZone(){
    return TimeZone.getDefault().getDisplayName();
  }