equals method in Java

[vinay kalal]

Hello
I have a simple confusion.When we use equals() method in Java it means we gonna compare the actual value of that object.But i am not getting correct output in my cases.Does it mean equals() method is use to compare the value of instance variable of classes because instance variables are the state of object.So totally confuse.I have an code below which is giving false output.

class E {
	int x = 5;
}

class F {
	int y= 5;

}

public class Equals {

	public static void main(String[] args) {
		E e = new E();

		F f = new F();

		System.out.println(e.equals(f));

	}

}

[Henry Wong]

vinay kalal wrote:When we use equals() method in Java it means we gonna compare the actual value of that object

Correct, but it actually have to be implemented -- String, Integer, Double, etc. all implements / override the equals() method to correctly compare the values.

Henry

[Greg Brannon]

Try printing e and f to see what is being compared with equals() to better understand the result you're getting now.

[Lester Burnham]

Also read How to Write an Equality Method in Java for more information.

[Campbell Ritchie]

Lester Burnham wrote:Also read How to Write an Equality Method in Java for more information.

That's a good article; two other useful references are Effective Java by Joshua Bloch (you might find a sample chapter of the 1st edition on the web), and Angelika Langer's pages: Google for Angelika Langer Java equals hashCode.

[rk sharma]

It will give "false" as output obviously. because .the default equals() method always compares the references and not the contents. we have to overrride the equals() method as per our requirement.

[venkatesh Nunna]

public class test {
public static void main(String args[]) {
String s1 = "abc";
String s2 = new String("abc");
if(s1.equals(s2))
System.out.println(3);
else
System.out.println(4);
}
}

If i run the above code, it returns 3. I think object s1 and s2 references are different , but why it returns true.

[Unnar Björnsson]

venkatesh Nunna wrote:public class test {
public static void main(String args[]) {
String s1 = "abc";
String s2 = new String("abc");
if(s1.equals(s2))
System.out.println(3);
else
System.out.println(4);
}
}

If i run the above code, it returns 3. I think object s1 and s2 references are different , but why it returns true.

Because the String class overrides the equals method to compare the string value instead of the references