CODEWITHSUNDEEP
java
jack peterson
jack peterson

Reputation: 297

creating new instance in java classes

I'm new in java and I saw this sample code. I don't know why in JavaApplication.java file we need to create a new instance by new keyword to set the goat name but in Tiger.java there is no need to create a new instance by new keyword to set the goat name! what's the difference?

JavaApplication.java

public static void main(String[] args) {
    Tiger t = new Tiger();
    Goat g = new Goat();
    Goat g1 = new Goat();
    g.name = "goaty";
    g1.name = "goatia";
    t.name = "woofy";
    t.hunt(g);
    t.hunt(g1);
}

Tiger.java

public class Tiger {
    String name;
    void hunt(Goat food) {
        System.out.println(name + " ate " + food.name);
    }
}

Goat.java

public class Goat {
    String name;
}

Upvotes: 1

Views: 340

Answers (4)

Dishonered
Dishonered

Reputation: 8841

A Goat can be created only by using the 'new' keyword. After a goat is created you can give this goat to a tiger to eat. So this goat here

 void hunt(Goat food) {
    System.out.println(name + " ate " + food.name);
}

is already created so you don't have to create it again. Of course you can initate it again but it would be pointless since if a tiger could create a goat by itself it would not need to hunt goats.

Upvotes: 1

Furqan Anwar
Furqan Anwar

Reputation: 45

As far as i can see you have placed Goat food as parameter which means hunt method will accept an object of type Goat basically food is reference variable of type Goat.So any thing that a Goat can do should apply to food also.In your Goat class you have only a field of name .So whenever you create an object you can just give it a name that's it .Now you are passing Goat object into your method so in order to printout food.name your goat needs to have a name first.

Upvotes: 1

nilima akter
nilima akter

Reputation: 59

In Tiger class inside the function hunt, food is a parameter of type Goat and a parameter doesn't need to be instantiated by the new keyword. Only the object needs to be instantiated.

Upvotes: 2

Jomarie Cajes
Jomarie Cajes

Reputation: 19

I'm also new at java but what I understand in java is that you can't link non-static method/variable to a static one and in order to do so, you need to create an instance for it. :) the new keyword is needed to create an instance of it btw..

Upvotes: 1

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