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Chapter 30 The java.util Package |
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Chapter 30 The java.util Package |
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This abstract class defines methods used to perform date and time arithmetic. It also includes methods that convert dates and times to and from the machine-usable millisecond format used by the Date class and units like minutes, hours, days, weeks, months, and years that are more useful to humans.
As an abstract class, Calendar cannot be directly instantiated. Instead, it provides static getInstance() methods that return instances of a Calendar subclass suitable for use in a specified or default locale with a specified or default time zone.
Calendar defines a number of useful constants. Some of these are values that represent days of the week and months of the year. Other constants, such as HOUR and DAY_OF_WEEK, represent various fields of date and time information. These field constants are passed to a number of Calendar methods, such as get() and set(), in order to indicate what particular date or time field is of interest.
setTime() and the various set() methods set the date represented by a Calendar object. The add() method adds (or subtracts) values to a calendar field, incrementing the next larger field when the field "rolls over." roll() does the same, without modifying any but the specified field. before() and after() compare two Calendar objects.
Many of the methods of the Calendar class are replacements for methods of Date that have been deprecated in Java 1.1. While the Calendar class is used to convert a time value into its various hour, day, month, and other fields, it is not intended to present those fields into a form suitable for display to the end user. That function is performed by the DateFormat class in the java.text package, which handles internationalization issues.
See also Date, DateFormat, and TimeZone.
public abstract class Calendar extends Object implements Serializable, Cloneable {
// Protected Constructors
protected Calendar();
protected Calendar(TimeZone zone, Locale aLocale);
// Constants
public static final int FIELD_COUNT;
// Date and Time Field Constants
public static final int ERA;
public static final int YEAR;
public static final int MONTH;
public static final int WEEK_OF_YEAR, WEEK_OF_MONTH;
public static final int DATE, DAY_OF_MONTH;
public static final int DAY_OF_YEAR, DAY_OF_WEEK, DAY_OF_WEEK_IN_MONTH;
public static final int ZONE_OFFSET, DST_OFFSET;
public static final int AM_PM;
public static final int HOUR, HOUR_OF_DAY;
public static final int MINUTE;
public static final int SECOND;
public static final int MILLISECOND;
// Field Value Constants
public static final int JANUARY, FEBRUARY, MARCH, APRIL;
public static final int MAY, JUNE, JULY, AUGUST;
public static final int SEPTEMBER, OCTOBER, NOVEMBER, DECEMBER;
public static final int UNDECIMBER;
public static final int SUNDAY, MONDAY, TUESDAY, WEDNESDAY;
public static final int THURSDAY, FRIDAY, SATURDAY;
public static final int AM, PM;
// Protected Instance Variables
protected boolean areFieldsSet;
protected int[] fields;
protected boolean[] isSet;
protected boolean isTimeSet;
protected long time;
// Class Methods
public static synchronized Locale[] getAvailableLocales();
public static synchronized Calendar getInstance();
public static synchronized Calendar getInstance(TimeZone zone);
public static synchronized Calendar getInstance(Locale aLocale);
public static synchronized Calendar getInstance(TimeZone zone, Locale aLocale);
// Public Instance Methods
public abstract void add(int field, int amount);
public abstract boolean after(Object when);
public abstract boolean before(Object when);
public final void clear();
public final void clear(int field);
public Object clone(); // Overrides Object
public abstract boolean equals(Object when); // Overrides Object
public final int get(int field);
public int getFirstDayOfWeek();
public abstract int getGreatestMinimum(int field);
public abstract int getLeastMaximum(int field);
public abstract int getMaximum(int field);
public int getMinimalDaysInFirstWeek();
public abstract int getMinimum(int field);
public final Date getTime();
public TimeZone getTimeZone();
public boolean isLenient();
public final boolean isSet(int field);
public abstract void roll(int field, boolean up);
public final void set(int field, int value);
public final void set(int year, int month, int date);
public final void set(int year, int month, int date, int hour, int minute);
public final void set(int year, int month, int date, int hour, int minute, int second);
public void setFirstDayOfWeek(int value);
public void setLenient(boolean lenient);
public void setMinimalDaysInFirstWeek(int value);
public final void setTime(Date date);
public void setTimeZone(TimeZone value);
// Protected Instance Methods
protected void complete();
protected abstract void computeFields();
protected abstract void computeTime();
protected long getTimeInMillis();
protected final int internalGet(int field);
protected void setTimeInMillis(long millis);
}
GregorianCalendar
DateFormat.setCalendar()
Calendar.getInstance(), DateFormat.getCalendar()
DateFormat.calendar
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| java.util.BitSet (JDK 1.0) |  |
java.util.Date (JDK 1.0) |
