Util.java

package moontime.droid.util;

import java.text.DateFormatSymbols;
import java.util.Arrays;
import java.util.Calendar;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import com.google.common.primitives.Ints;

public class Util {

  public static final ImmutableList<String> MONTH_SHORT_NAMES = ImmutableList.copyOf(Lists.partition(
      Arrays.asList(new DateFormatSymbols().getShortMonths()), 12).get(0));

  public static final ImmutableSet<Integer> CALENDAR_FIELDS = ImmutableSet.of(Calendar.YEAR, Calendar.MONTH,
      Calendar.DATE, Calendar.HOUR_OF_DAY, Calendar.MINUTE, Calendar.SECOND, Calendar.MILLISECOND);

  public static int getMonth(String shortName) {
    for (int i = 0; i < MONTH_SHORT_NAMES.size(); i++) {
      if (MONTH_SHORT_NAMES.get(i).equals(shortName)) {
        return i;
      }
    }
    throw new IllegalStateException("month '" + shortName + "' not found in " + MONTH_SHORT_NAMES);
  }

  public static long hoursToMillis(int hours) {
    return hours * 1000 * 60 * 60;
  }

  public static void resetFields(Calendar calendar, int... fieldsToReset) {
    for (int field : fieldsToReset) {
      resetCalendarField(calendar, field);
    }
  }

  public static void resetFieldsExcept(Calendar calendar, int... fieldsToKeep) {
    for (int field : Sets.difference(CALENDAR_FIELDS, ImmutableSet.of(Ints.asList(fieldsToKeep)))) {
      resetCalendarField(calendar, field);
    }
  }

  private static void resetCalendarField(Calendar calendar, int field) {
    if (field == Calendar.DATE || field == Calendar.DAY_OF_MONTH) {
      calendar.set(field, 1);
    } else {
      calendar.set(field, 0);
    }
  }

  public static boolean equalsInFields(Calendar calendar1, Calendar calendar2, int... fields) {
    for (int field : fields) {
      if (calendar1.get(field) != calendar2.get(field)) {
        return false;
      }
    }
    return true;
  }

  public static void copyFields(Calendar calendarFrom, Calendar calendarTo, int... fields) {
    for (int field : fields) {
      calendarTo.set(field, calendarFrom.get(field));
    }
  }

  public static String wrap(String string, String tag) {
    return String.format("<%2$s>%0$s</%2$s>", string, tag);
  }

}