equals

I want to demonstrate with a few line of code that in Java, that to compare two strings ( String ), you have to use equals() instead of the operator == . Here is something I tried : public static void main(String Args[]) { String s1 = "Hello"; String s2 = "Hello"; if (s1 == s2) System.out.println("same strings"); else System.out.println("different strings"); } I was expecting this output : different strings , because with the test s1 == s2 I'm actually comparing two references (i.e. addresses) instead of the objet's content. But I actually got this output : same strings ! Browsing the internet

I am using Visual Studio 6 with some old time code written in c. I found an issue where the code looks like this.. int x = 3; float y = 3.0; if(x == y){ do some crazy stuff } is this a valid comparison? is it possible at run time the allocation for the float is 3.0000001 and this would fail? Well, I guess you won't be too surpised to hear that comparing floats for equality is a rookie mistake then. The problem is that many increments smaller than an integer values can't actually be represented exactly in IEEE floating point. So if you arrive at the float by trying to "index" it up to the value

I'm going through a book on data structures. Currently I'm on graphs, and the below code is for the vertex part of the graph. class Vertex<E>{ //bunch of methods public boolean equals(Object o){ //some code } } When I try to implement this equals method my compiler complains about not checking the type of the parameter and just allowing any object to be sent it. It also does seem a bit strange to me why that parameter shouldn't be a Vertex instead of an Object. Is there a reason why the author does this or is this some mistake or antiquated example? @Override public boolean equals(Object obj)