patternjavaMinor

Creating date strings and setting dates

Submitted by: @import:stackexchange-codereview·Mar 10, 2026·

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creatingdatesdatesettingandstrings

Problem

I've created a Java class, Date, in which I basically create date strings and set dates. Is there anything I can do besides adding comments to improve/shorten my code?

I've tested all of my methods to see if they work correctly, and they all work as planned. I haven't done tests that force the IllegalArgumentsException to be thrown yet though.

I've tried changing the instantiated boolean variable shortDisplay have a default value of true, which has made my program work correctly as far as I know.

I'm assuming when you declare a boolean instance variable, you need to also declare what its default value should be, otherwise issues arise. If anyone could comment on why that is, that would be great.

Date.java

```
public class Date {
private int year;
private int month;
private int day;
private boolean shortDisplay = true;

public Date() {
setDate(2000, 01, 01);
}

public Date(int yy, int mm, int dd) {
setDate(yy, mm, dd);
}

public Date(int yy, int mm) {
setDate(yy, mm);
}

public Date(int yy) {
setDate(yy);
}

public Date(Date otherDate) {
setDate(otherDate);
}

public Date(String dateStr) {
setDate(dateStr);
}

public void setDate(int yy, int mm, int dd) {
setYear(yy);
setMonth(mm);
setDay(dd);
}

public void setDate(int yy, int mm) {
setYear(yy);
setMonth(mm);
setDay(1);
}

public void setDate(int yy) {
setYear(yy);
setMonth(1);
setDay(1);
}

public void setDate(Date otherDate) {
int yy = getYear();
int mm = getMonth();
int dd = getDay();
setYear(yy);
setMonth(mm);
setDay(dd);
}

public void setDate(String dateStr) {
int length = dateStr.length();
int indexCount = 0;
if (length >= 0) { // basically checking to see if the date even exists
if (dateStr.in

Solution

Your class does not handle months with less than 31 days, in-real-life-speaking your unit test for adding five days to 28th April is already wrong

stringMonth can be left as a private static final array, so that you are not re-creating it every time monthString() is called

equals() implementation does not check for null/class type, and by right you should have a corresponding hashCode() implementation too

before() can probably be better implemented as compareTo() if you can consider letting your class implement Comparable

There are better ways of formatting the String representation in toString() and parsing a String date in setDate(String dateStr)

Some Javadocs will be helpful too, especially to indicate the format that you are using in toString() ("MM/DD/YY")

Consider a proper testing framework such as JUnit or TestNG?

Context

StackExchange Code Review Q#47316, answer score: 5

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