Object and references in java

Question

I am confused as I am new to java, how many objects and references are created in the following piece of code?

MyClass t = new MyClass();
MyClass s = new MyClass();
MyClass v = s;

Please explain the answer:

2 Objects
3 References

Psst: Java is case-sensitive. MYclass != MyClass != Myclass. — JB Nizet, Dec 17 '11 at 18:10

score 6 · Accepted Answer · answered Dec 17 '11 at 18:18

6

A picture is worth more than a thousand words:

enter image description here

answered Dec 17 '11 at 18:18

Eng.Fouad

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score 2 · Answer 2 · answered Dec 17 '11 at 18:07

2

An object is an instance of a class, created with new. You use new twice, so there are two objects.^*

A variable is, generally speaking, a reference.^** So there are three references (t, s, v), although two of them happen to refer to the same object.

_{* Of course, MyClass itself might create more objects internally.}

_{** Except in the case of primitive types, like int, float, etc.}

answered Dec 17 '11 at 18:07

Oliver Charlesworth

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ok.. so u mean to say that v and s are reference to same mem location.? – sum2000 Dec 17 '11 at 18:11

score 2 · Answer 3 · answered Dec 17 '11 at 18:08

2

2 Object and

3 reference

if you do new you are creating object so there are two new so simply two Objects

and if you define

Foo a;// you have just created a reference

_{* Note: new is only a way to create object, it can be created using otherways too}

answered Dec 17 '11 at 18:08

jmj

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What are other ways to create an object other than `new` (not including things like `clone` which will call `new` internally?) – Oliver Charlesworth Dec 17 '11 at 18:13
@Oli http://stackoverflow.com/questions/95419/what-are-all-the-different-ways-to-create-an-object-in-java – jmj Dec 17 '11 at 18:14

score 2 · Answer 4 · answered Dec 17 '11 at 18:08

2

So you are creating a new object and storing a reference to that object in t. The same for s. Then you are assigning the s reference to v (not creating a new object). So you have three references and two objects.

answered Dec 17 '11 at 18:08

James Hull

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score 0 · Answer 5 · answered Dec 17 '11 at 18:09

0

Actually, your answer is wrong. It's the other way around:

2 objects (in the first two lines)

3 references (t, s, v, v and s share an object)

answered Dec 17 '11 at 18:09

nfechner

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Object and references in java

5 Answers5