public boolean equals (Object obj)

[Mahi Rahman]

Hello!
I have an interesting problem with the following code. Whenever I try to run this program it gives me false(No!) for (date.equals(date2)) method even though it should return true(Yes!). I tried to figure out the fault using debugger but could not succeded. Can anyone please help me?

Mahi.

//Code for the class definition.
public class Date {
int dd;
int mm;
int yy;

public Date(int dd, int mm, int yy) {
this.dd = dd;
this.mm = mm;
this.yy = yy;
}
public int getDd() {
return dd;
}
public int getMm() {
return mm;
}
public int getYy() {
return yy;
}
public void setDd(int dd) {
this.dd = dd;
}
public void setMm(int mm) {
this.mm = mm;
}
public void setYy(int yy) {
this.yy = yy;
}
public String toString() {
return (dd+"."+mm+"."+yy);
}

public boolean equals (Date other){
return (this.dd == other.dd && 
this.mm == other.mm &&
this.yy == other.yy);

}
}
 
//code for the main method
public class TestDate {
 
public static void main(String[] args) {
Date date = new Date( 12, 02, 2007);
System.out.println("Default date: "+date.getDd()+" "+date.getMm()+" "+date.getYy());

// Calling the set methods
date.setDd(19);
date.setMm(7);
date.setYy(2005);
System.out.println("After modification the new date: "+date.getDd()+" "+date.getMm()+" "+date.getYy());

System.out.println("Date: "+date.toString());

Object date1 = new Date (31, 12, 2003);
Object date2 = new Date (19, 7, 2005);
Object date3 = new Date (31, 12, 2003);
System.out.println("Date: "+(date));
System.out.println("Date1: "+(date1));
System.out.println("Date2: "+(date2));
System.out.println("Date3: "+(date3));

System.out.println("Is the date and date1 contain the same date?");
if (date.equals(date1)){
System.out.println("Yes!");
}
else {
System.out.println("No!");
}
System.out.println("Is the date and date2 contain the same date?");
if (date.equals(date2)) {
System.out.println("Yes!");
}
else { 
System.out.println("No!");
}
System.out.println("Is the date1 and date2 contain the same date?");
if (date1.equals(date2)) {
System.out.println("Yes!"); 
}
else {
System.out.println("No!");
}
System.out.println("Is the date1 and date3 contain the same date?");
if (date1.equals(date3)) {
System.out.println("Yes!");
}
else { 
System.out.println("No!");
}
System.out.println("Is the date2 and date3 contain the same date?");
if (date2.equals(date3)) {
System.out.println("Yes!");
}
else { 
System.out.println("No!");
}

}
}

EDIT by mw: Added Code Tags.
[ February 16, 2007: Message edited by: marc weber ]

[marc weber]

Welcome to JavaRanch!

Your date is a reference of type Date. But your date1, date2, and date3 are all of type Object.

You've overloaded the equals method to take a Date object, but when you call it using an Object as an argument, the equals method inherited from Object is invoked. (Remember, calls to overloaded methods are resolved based on the arguments' reference types -- not their true runtime types. This is different than overridden method calls, which are resolved based on the calling object's true runtime type.)
[ February 16, 2007: Message edited by: marc weber ]

[Mahi Rahman]

Thanks Marc!
I now understand what was the flaw in my code. Also thanks for editing with [CODE] tags. Cheers!