sinequanon:


I said it works in some situations. You queried this. You were wrong.

Your explanation is not quite right, either. In my example, string1 and string2 are two separate objects.

You are not getting it. So I'll explain it. They are pointing to (I should say referencing to since this is Java) to the same object.

== never and I repeat never checks for the actual value of a string. If you don't believe me, you are more than welcome to check Java forums like coderanch.com or many other popular Java related forums they will tell you the same exact thing.

Oh okay, I see what Fulaman198 is saying now. My question now would be...

String string1 = "This is a test.";
String string2 = "This is a test.";

How do these two count as the same object? I'd have imagined that the JVM would distinguish string1 and string2 as separate objects. I'm asking because I honestly don't know. I'm a novice at Java.

Fulaman198:


You are not getting it. So I'll explain it. They are pointing to (I should say referencing to since this is Java) to the same object.

== never and I repeat never checks for the actual value of a string. If you don't believe me, you are more than welcome to check Java forums like coderanch.com or many other popular Java related forums they will tell you the same exact thing.

You are not getting it.

"== never checks" is meaningless. == is a syntax.

The compiler is doing the work, and it is not doing it exactly the way you have described. You are fudging your use of the word "object".

The reason it works is because the string is interned, which means that it gets only one copy at runtime.

Just as a test, I created and compiled three different scenarios to see what the results would be when I ran the code... Here's what I got.

class SomeClass {

    public static void main(String[] args) {

        // Scenario 1 .. String Literals
        String string1 = "This is a string test.";
        String string2 = "This is a string test.";

        // Scenario 2 .. String Literal vs String Object
        String string1 = "This is a string test.";
        String string2 = new String("This is a string test." );

        // Scenario 3 .. String Input via Scanner
        Scanner in = new Scanner(System.in);
        String string1 = in.nextLine(); // input "This is a string test."
        String string2 = in.nextLine(); // input "This is a string test."

        System.out.println((string1 == string2));
        System.out.println(string1.equals(string2));

        // Scenario 1 output .. true true
        // Scenario 2 output .. false true
        // Scenario 3 output .. false true

    }

}

Judging by the output, I would say best practice would be to use the string method .equals(), unless you know ahead of time that both strings will be literals. If you do not have that foresight, then always stick with .equals().

ChinenyeN:
Judging by the output, I would say best practice would be to use the string method .equals(), unless you know ahead of time that both strings will be literals. If you do not have that foresight, then always stick with .equals().

Correct!

It you know that they will be string literal constants (or, Integers in some cases), it is safe.

sinequanon:
The reason it works is because the string is interned, which means that it gets only one copy at runtime.

Okay. So this is what Fulaman198 meant when he referred to them being the same object. I understand now. Thanks, both of you.

ChinenyeN:
Oh okay, I see what Fulaman198 is saying now. My question now would be...

String string1 = "This is a test.";
String string2 = "This is a test.";

How do these two count as the same object? I'd have imagined that the JVM would distinguish string1 and string2 as separate objects. I'm asking because I honestly don't know. I'm a novice at Java.

Java has what is known as and referred to as a String Pool so sometimes == does indeed work. However == compares if objects are equal and not the value within the object itself.

In the case of "test"=="" test" being true, these values are interned strings. == tests for reference equality and the Object.equals() method tests for value or in this case string text equality.

// These two have the same value
new String("test" ).equals("test" ) // --> true 

// ... but they are not the same object
new String("test" ) == "test" // --> false 

// ... neither are these
new String("test" ) == new String("test" ) // --> false 

// ... but these are because literals are interned by 
// the compiler and thus refer to the same object
"test" == "test" // --> true 

// checks for nulls and calls .equals()
Objects.equals("test", new String("test" )) // --> true
Objects.equals(null, "test" ) // --> false

Does the explanation make sense?

Yes, the explanation does make sense. Thanks.

Fulaman198:
In the case of "test"=="" test" being true, these values are interned strings. == tests for reference equality and the Object.equals() method tests for value or in this case string text equality.

Object.equals() tests for "reference equality" (whether the same object is being referenced, just like == )

This is overridden in class String, to test for "value equality".

sinequanon:


Object.equals() tests for "reference equality" (whether the same object is being referenced, just like == )

This is overridden in class String, to test for "value equality".

What is object.equals() referencing? It's parsing and checking for a value. It's quite different from ==

Fulaman198:


What is object.equals() referencing? It's parsing and checking for a value. It's quite different from ==

If the runtime type of the object is Object, then .equals will behave the same as ==.

sinequanon:


If the runtime type of the object is Object, then .equals will behave the same as ==.

Ok

holy bump

ChinenyeN:
Honestly, I'm still trying to wrap my mind around Java (I'm going the self-taught route). It's been almost a month now since I started learning, and so far, I've come to understand the logic behind frameworks and packages. I've also come to understand classes and inheritance in Java, but it's taking me longer than I imagined it would to really get a handle on the language. So far, the best I've done, in my self-taught journey is to build a simple package to test out/learn some OOP principles.

I would like to get better with Java though. Overall, I'd say I've made some decent progress in the span of a few weeks of actual learning. Java has a ridiculously steep learning curve. C is so easy compared to this. Anyway, I imagine it would take me more time to become a strong Java programmer, but I believe I can at least get past the learning curve within the next coming months and probably get a good foundation in 3 - 6 months, maybe sooner if I prioritize. I project that I would be strong by the end of the year. It's not to say that I will claim to know the language inside-out, but I will at least be strong enough to know how to use Java to get things done.

it takes years to be a cute programmer but don't worry bout the years just keep on working towards it

Dekatron:
Looks like I was right in time


Please how do I get input in java??

Like . . I want to accept a string & then print. . . I am confused on the BufferedReading and Scanner.



I did :-

String c1 = getInput("Enter a colour";



It said I should create method getInput(String)


When I did I had :-

private String getInput (String String) {
return null;
}


If I return c1 instead of null, it will accept the String, but won't print. Will just continue accepting



Help me jare. . . Am stuck


cc : fulaman198, teempakguy (oya, Java is here ), dhtml18 & other guru programmers

considering yhu almost broke my head, that method is wrong


import java.util.Scanner;

public class Colour
{
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);

String colour;
System.out.println("Enter a colour:/n";
colour =in.nextLine();

System.out.println("you entered:/n%s/n", colour);

}
}


that should solve yhur problem just fine.

khaynoni:


A shorter solution but with a different programming language.



Python 3

I ran ur code on qpython3 and am having syntax error. Besides I've been reading books on Python and my syntax is still poor. Can I add u pls WhatsApp?

pxjosh:
I ran ur code on qpython3 and am having syntax error. Besides I've been reading books on Python and my syntax is still poor. Can I add u pls WhatsApp?

Corrected!
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