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| 5. 27. 9. Final类成员 |
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/*
* file: FinalMembers.java
* package: oreilly.hcj.finalstory
*
* This software is granted under the terms of the Common Public License,
* CPL, which may be found at the following URL:
* http://www-124.ibm.com/developerworks/oss/CPLv1.0.htm
*
* Copyright(c) 2003-2005 by the authors indicated in the @author tags.
* All Rights are Reserved by the various authors.
*
########## DO NOT EDIT ABOVE THIS LINE ########## */
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;
/**
* Demonstration of final class members.
*
* @author <a href=mailto:kraythe@arcor.de>Robert Simmons jr. (kraythe)</a>
* @version $Revision: 1.3 $
*/
public class FinalMembers {
/** Holds the creation date-time of the instance. */
private Date creationDate =
Calendar.getInstance(TimeZone.getTimeZone("GMT"))
.getTime();
/** Holds the modification date-time of the instance. */
public Date modificationDate = creationDate;
/**
* Holds the creation date-time of the instance. A protected version of createDate.
*/
private final Date creationDate2 =
Calendar.getInstance(TimeZone.getTimeZone("GMT"))
.getTime();
/** Holds the creation date-time of the instance. */
private final Date creationDate3;
/**
* Constructor
*
* @param creationDate The creation date.
* @param modificationDate The last modification date.
*
* @throws IllegalArgumentException if modificationDate is less than creationDate.
*/
public FinalMembers(final Date creationDate, final Date modificationDate) {
if (modificationDate.compareTo(creationDate) < 0) {
throw new IllegalArgumentException("modificationDate");
}
this.creationDate3 = creationDate;
// do a bunch of date calculations.
// this.creationDate3 = modificationDate; // <= compiler error
}
/**
* Second constructor. Use current date for creation date.
*
* @param modificationDate The last modification date.
*/
public FinalMembers(final Date modificationDate) {
this.modificationDate = modificationDate;
// <= compiler error: ?reationDate may not have been initialized?
creationDate3 = null; // comment this out to get the compiler error.
}
/**
* Get the Date-Time when the object was created.
*
* @return The creation date of the object.
*/
public Date getCreationDate() {
return this.creationDate;
}
/**
* Get the Date-Time when the object was created. A protected version of createDate.
*
* @return The creation date of the object.
*/
public Date getCreationDate2() {
return this.creationDate2;
}
/**
* Set the modification date of the object.
*
* @param modificationDate The new modification date.
*/
public void setModificationDate(Date modificationDate) {
this.creationDate = modificationDate;
}
/**
* Get the modification date.
*
* @return The current modification date.
*/
public Date getModificationDate() {
return this.modificationDate;
}
/**
* Set the modification date of the object.
*
* @param modificationDate The new modification date.
*
* @throws NullPointerException If the modification date is null.
*/
public void setModificationDate2(Date modificationDate) {
if (modificationDate == null) {
throw new NullPointerException();
}
// this.creationDate2 = modificationDate; // <= Compiler error.
}
/**
* Used just to supress eclipse warnings on unused variables; irrelevant to the
* example.
*/
protected void supress() {
System.out.println(this.creationDate3);
}
}
/* ########## End of File ########## */
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