I am new in java, and please ask me what this code is mean?
Image img = new ImageIcon("2.png")
how can image class type link create another object?
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please elaborate the question? – Ashok Kumar N Feb 03 '19 at 16:07
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1Please read about Object-oriented concepts in [The Java Tutorial](https://docs.oracle.com/javase/tutorial/java/concepts/index.html), a Java book etc. – RealSkeptic Feb 03 '19 at 16:08
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What that code does mean? – Sasun Hakobyan Feb 03 '19 at 16:09
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2That code means "Create an object of type `ImageIcon` using the argument `2.png`, and assign a reference to that object to the variable `img` which is of type `Image`". – RealSkeptic Feb 03 '19 at 16:12
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Please see: [How much research effort is expected of Stack Overflow users?](https://meta.stackoverflow.com/questions/261592/how-much-research-effort-is-expected-of-stack-overflow-users) – Turing85 Feb 03 '19 at 16:16
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https://stackoverflow.com/questions/32434494/difference-between-assigning-instantiation-to-parent-class-and-derived-class – Sotirios Delimanolis Feb 03 '19 at 16:25
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https://stackoverflow.com/questions/383947/what-does-it-mean-to-program-to-an-interface – Sotirios Delimanolis Feb 03 '19 at 16:26
1 Answers
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A variable of type Image can refer to an instance of ImageIcon if ImageIcon either extends or implements Image (directly or indirectly). (I should note that the only ImageIcon class I know, javax.swing.ImageIcon does not and so that code wouldn't compile. Presumably you're using something else.)
In general, a superclass-typed variable can refer to a subclass object, and an interface-typed variable can refer to any object whose class implements that interface. This is vital for polymorphism in Java.
I suggest going through the Java Inheritance Tutorial for more. You may also find my answer to this other question useful.
T.J. Crowder
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but what is different if i will write like this - ImageIcon img = new ImageIcon("2.png") – Sasun Hakobyan Feb 03 '19 at 16:13
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@SasunHakobyan - I suspected that might be what the rest of that comment was going to be. :-) See [this question's answers](https://stackoverflow.com/questions/1348199/what-is-the-difference-between-the-hashmap-and-map-objects-in-java), in particular [mine](https://stackoverflow.com/questions/1348199/what-is-the-difference-between-the-hashmap-and-map-objects-in-java/1348228#1348228). – T.J. Crowder Feb 03 '19 at 16:15