这是对我之前问题的修改，因为每个建议都无法解决主要问题。在我的程序中，由于某种原因，monthName，year和day的值在程序期间消失。此Test程序的输出为null，0,0。顺便说一句，LongDate继承自Date类，而不是java.util.Date，而是我创建的类，editDay和editYear是Date类中列出的方法。
非常感谢。任何提示赞赏。
public class Test {
public static void main(String[] args) {
//creates an array of type Date filled with two LongDate objects
Date [] collectionOfDates = { new LongDate("February",2,1996), new LongDate("February",13,1999) };
// loops through the array and displays output of getDate() for each object
for( int i = 0; i < collectionOfDates.length; i++ ) {
System.out.println( collectionOfDates[i].getDate() );
}
}
}
这是LongDate类：
public class LongDate extends Date {
private String monthName;
private int day;
private int year;
public LongDate(String m, int d, int y) {
super.editDay(d);
super.editYear(y);
editMonth(m);
}
public void setDate(String m, int d, int y) {
monthName = m;
day = d;
year = y;
}
public String getDate() {
StringBuilder fullDate = new StringBuilder();
fullDate.append(monthName);
fullDate.append(" ");
fullDate.append(day);
fullDate.append(", ");
fullDate.append(year);
return fullDate.toString();
}
public String getShortDate() {
int month = 0;
if (monthName.equals("January")) {
month = 1;
} else if (monthName.equals("February")) {
month = 2;
} else if (monthName.equals("March")) {
month = 3;
} else if (monthName.equals("April")) {
month = 4;
} else if (monthName.equals("May")) {
month = 5;
} else if (monthName.equals("June")) {
month = 6;
} else if (monthName.equals("July")) {
month = 7;
} else if (monthName.equals("August")) {
month = 8;
} else if (monthName.equals("September")) {
month = 9;
} else if (monthName.equals("October")) {
month = 10;
} else if (monthName.equals("November")) {
month = 11;
} else if (monthName.equals("December")) {
month = 12;
}
StringBuilder shortDate = new StringBuilder();
shortDate.append(month);
shortDate.append("/");
shortDate.append(day);
shortDate.append("/");
shortDate.append(year);
return shortDate.toString();
}
protected String editMonth(String m) {
// asks person to try again if month is not capitalized and spelled properly
if (!m.equals("January") && !m.equals("February") && !m.equals("March") && !m.equals("April") && !m.equals("May") && !m.equals("June") && !m.equals("July") && !m.equals("August") && !m.equals("September") && !m.equals("October") && !m.equals("November") && !m.equals("December")) {
m = Input.getString( "Invalid month. Please type the month again." );
return m;
} else
return m;
}
}